CN115632712B - Demultiplexer and system, method and device for measuring qubit state - Google Patents

Abstract

Embodiments of the present application provide a signal separator and a measurement system, method, and device for a state of a qubit, wherein the method includes: converting an initial frequency sweep signal into an initial resonance signal and inputting it to a quantum dot device to be measured; obtaining a quantum A target resonance signal returned by a dot device; a target signal that separates a target frequency component from the target resonance signal, where the target frequency component is a frequency associated with a charge tunneling event within a quantum dot device; detection of a dispersion frequency shift in the target signal . Through this application, the problem of low accuracy of measuring the state of silicon-based spin qubits by means of dispersion readout is solved, and then the measurement of the state of silicon-based spin qubits by way of dispersion readout is improved. effect on accuracy.

Description

Demultiplexer and measurement system, method and device for qubit state

technical field

The embodiments of the present application relate to the field of silicon-based devices, and in particular, relate to a signal separator and a measurement system, method and device for a state of a qubit.

Background technique

At present, due to the intrinsic properties of silicon-based spin qubits, the spin state of qubits cannot be directly measured. The existing technology generally measures them equivalently by means of charge sensing or dispersion readout. However, for the dispersion readout method, the measurement process is easily disturbed by signal noise. For example, if the dispersion readout method is operated at a high temperature, background noise may gradually overwhelm the information carrying the state information of the spin qubit. In the case of measuring the signal, the result is that the readout visibility is reduced by the thermal broadening of the Coulomb peak, which directly blurs the V-shaped pattern of the Rabi oscillation (Rabi oscillation) detected for judging the state of the qubit, affecting the qubit state. Accuracy and measurement efficiency of bit state measurements.

Aiming at the low accuracy of measuring the state of silicon-based spin qubits by means of dispersion readout in related technologies, no effective solution has been proposed yet.

Contents of the invention

The embodiment of the present application provides a signal separator and a qubit state measurement system, method and device to at least solve the low accuracy of measuring the silicon-based spin qubit state by means of dispersion readout in the related art The problem.

According to an embodiment of the present application, a signal splitter is provided, including: a first straight waveguide, a second straight waveguide and a ring waveguide,

The first straight waveguide is connected to the second straight waveguide through the ring waveguide;

The ring waveguide includes: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide, wherein the first half ring waveguide is embedded in the first straight waveguide to form a first coupling region , the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to form a first transmission between the first half-ring waveguide and the second half-ring waveguide zone, the second transmission waveguide connection forms a second transmission zone between the second half-ring waveguide and the first half-ring waveguide;

The length parameter of the ring waveguide is determined according to the target frequency component of the dispersion frequency shift during the measurement process of the silicon-based spin qubit state;

The signal separator is used to separate the target signal of the target frequency component from the received signal.

In an exemplary embodiment, both the first transmission waveguide and the second transmission waveguide are meander-shaped waveguides, wherein,

The first transmission waveguide includes a first number of first meandering periods connected in sequence, and the first meandering period includes a first partial ring segment, a first straight line segment, a first semi-ring segment, a second straight line segment and the second part of the ring segment;

The second transmission waveguide includes a second number of second meandering periods connected in sequence, and the second meandering period includes a third partial ring segment, a third straight line segment, a second semi-ring segment, a fourth Straight line segment and the fourth part ring segment;

The first quantity is the same as or different from the second quantity.

In an exemplary embodiment, the first number is the same as the second number, the radii of the first half-ring waveguide and the second half-ring waveguide are the same, the first partial ring segment, the first half-ring waveguide Two ring segments, the third ring segment, the fourth ring segment, the first half ring segment and the second half ring segment have the same radius, the first straight line segment, the first ring segment The lengths of the two straight line segments, the third straight line segment and the fourth straight line segment are the same.

According to another embodiment of the present application, a qubit state measurement system is provided, including: a signal source, a signal converter, a signal separator and a detector, wherein,

The signal source is connected to the signal converter, and the signal converter is also connected between the quantum dot device to be measured and the signal separator, and the signal separator is connected to the detector;

The signal source is used to transmit an initial frequency sweep signal to the signal converter;

The signal converter is used to convert the initial sweep signal into an initial resonance signal and input it to the quantum dot device, and transmit the target resonance signal returned by the quantum dot device to the signal separator;

The signal separator is configured to separate a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event in the quantum dot device;

The detector is configured to detect the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the signal output by the signal converter indicates that the charge tunneling event occurs in the quantum dot device, The charge tunneling event is used to characterize the silicon-based spin qubit state within the quantum dot device.

In an exemplary embodiment, the signal splitter includes: a microring resonator, wherein the microring resonator includes: a first straight waveguide, a second straight waveguide and a ring waveguide,

The first straight waveguide is connected to the second straight waveguide through the ring waveguide, the input port of the first straight waveguide is connected to the signal converter, and the output port of the second straight waveguide is connected to the detection device connection;

The target frequency component is a resonance condition of the microring resonator;

The microring resonator is configured to input the target resonance signal from the input port, and output the target signal satisfying the resonance condition from the output port.

In an exemplary embodiment, the resonant frequency of the microring resonator is within the dispersion frequency shift range of the signal converter, and the full width at half maximum of the microring resonator is smaller than the bandwidth of the signal converter.

In an exemplary embodiment, the ring waveguide includes: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide, wherein,

The first half-ring waveguide is embedded in the first straight waveguide to form a first coupling region, the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to the A first transmission region is formed between the first half ring waveguide and the second half ring waveguide, and the second transmission waveguide is connected to form a second transmission region between the second half ring waveguide and the first half ring waveguide district;

The length parameter of the ring waveguide is determined according to the target frequency component.

In an exemplary embodiment, both the first transmission waveguide and the second transmission waveguide are meander-shaped waveguides, wherein,

said first transmission waveguide comprises a first number of first serpentine periods connected in sequence;

said second transmission waveguide comprises a second number of second serpentine periods connected in sequence;

The first quantity is the same as or different from the second quantity.

In an exemplary embodiment, the first meandering period includes a first partial ring segment, a first straight segment, a first semi-ring segment, a second straight segment and a second partial ring segment connected in sequence;

The second meandering cycle includes a third partial ring segment, a third straight line segment, a second half ring segment, a fourth straight line segment and a fourth partial ring segment connected in sequence.

In an exemplary embodiment, the first number is the same as the second number, the radii of the first half-ring waveguide and the second half-ring waveguide are the same, the first partial ring segment, the first half-ring waveguide Two ring segments, the third ring segment, the fourth ring segment, the first half ring segment and the second half ring segment have the same radius, the first straight line segment, the first ring segment The lengths of the two straight line segments, the third straight line segment and the fourth straight line segment are the same.

In an exemplary embodiment, the detector includes: an amplifier and an IQ mixer, wherein,

the amplifier is connected between the demultiplexer and the IQ mixer;

The IQ mixer is used to output the resonance peak of the target signal; and detect the dispersion frequency shift of the target signal according to the resonance peak.

In an exemplary embodiment, the signal converter includes: a grid reflectometer, or an LC resonator equivalent to the grid reflectometer.

According to another embodiment of the present application, a method for measuring the state of a qubit is provided, including:

Convert the initial frequency sweep signal into an initial resonance signal and input it to the quantum dot device to be measured;

Obtain the target resonance signal returned by the quantum dot device;

separating a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event within the quantum dot device;

Detecting the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the separated signal indicates that the charge tunneling event has occurred in the quantum dot device, and the charge tunneling event is used to characterize the Silicon-based spin qubit states within quantum dot devices.

In an exemplary embodiment, the separating the target signal of the target frequency component from the target resonance signal includes:

extracting a signal of a target frequency component from the target resonance signal to obtain a reference signal;

performing signal enhancement on the reference signal to obtain the target signal.

In an exemplary embodiment, the separating the target signal of the target frequency component from the target resonance signal includes:

The target signal of the target frequency component is separated from the target resonance signal by a microring resonator, wherein the microring resonator includes: a first straight waveguide, a second straight waveguide and a ring waveguide, the The first straight waveguide is connected to the second straight waveguide through the ring waveguide, the input port of the first straight waveguide is used to input the target resonance signal, and the output port of the second straight waveguide is used to output the The target signal of the resonance condition of the microring resonator, the resonance condition being the target frequency component.

In an exemplary embodiment, before the target signal of the target frequency component is separated from the target resonance signal by the microring resonator, the method further includes:

Determine the length parameter of the ring waveguide according to the target frequency component, wherein the ring waveguide includes: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide, the first The half-ring waveguide is embedded in the first straight waveguide to form a first coupling region, the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to the first half-ring waveguide A first transmission zone is formed between the waveguide and the second half-ring waveguide, and the second transmission waveguide connection forms a second transmission zone between the second half-ring waveguide and the first half-ring waveguide.

In an exemplary embodiment, the determining the length parameter of the ring waveguide according to the target frequency component includes:

Obtaining the dispersion frequency shift range of the signal converter, wherein the signal converter is used to convert the charge tunneling event in the quantum dot device into the dispersion frequency shift of the signal;

According to the material property of the microring resonator, the target frequency component is selected from the dispersion frequency shift range as the resonant frequency of the microring resonator, wherein the microring resonator having the resonant frequency FWHM is less than the bandwidth of the signal converter;

calculating a waveguide length of the ring waveguide according to the target frequency component;

Determine the radius of the semi-ring waveguide, the radius of the ring segment, the length of the straight line segment and the number of meandering cycles as the length parameter according to the length of the waveguide and the deployment information of the microring resonator;

Wherein, both the first transmission waveguide and the second transmission waveguide are meander-shaped waveguides, the first transmission waveguide includes a first number of first meandering periods connected in sequence, and the second transmission waveguide includes A second number of second meandering periods connected in sequence, the first number being the same as or different from the second number, the first meandering period comprising sequentially connected first partial ring segments, first straight line segments, second A half ring segment, a second straight line segment and a second partial ring segment, the second meandering period includes a third partial ring segment, a third straight line segment, a second half ring segment, a fourth straight line segment and a second half ring segment connected in sequence. four-part ring segment;

Wherein, the radius of the half-ring waveguide is the radius of the first half-ring waveguide and the second half-ring waveguide, and the ring segment radius is the first partial ring segment, the second partial ring segment, and the third ring segment. The partial annular segment, the fourth partial annular segment, the radius of the first semi-annular segment and the second semi-annular segment, the length of the straight line segment is the first straight line segment, the second straight line segment, The lengths of the third straight line segment and the fourth straight line segment and the number of meandering cycles are the sum of the first number and the second number.

According to another embodiment of the present application, a measurement device for a state of a qubit is provided, including:

The input module is used to convert the initial frequency sweep signal into an initial resonance signal and input it to the quantum dot device to be measured;

An acquisition module, configured to acquire the target resonance signal returned by the quantum dot device;

a separation module, configured to separate a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event in the quantum dot device;

A detection module, configured to detect the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the separated signal indicates that the charge tunneling event has occurred in the quantum dot device, and the charge tunneling event Used to characterize the silicon-based spin qubit state within the quantum dot device.

According to yet another embodiment of the present application, a computer-readable storage medium is also provided, and a computer program is stored in the computer-readable storage medium, wherein the computer program is configured to perform any one of the above-mentioned methods when running Steps in the examples.

According to yet another embodiment of the present application, there is also provided an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to perform any of the above Steps in the method examples.

Through this application, the initial sweep signal is converted into an initial resonance signal through a signal converter and input to the quantum dot device, and the target resonance signal returned by the quantum dot device is transmitted to the signal separator, and then the target resonance signal is obtained from the target resonance signal through the signal separator The target signal of the target frequency component is separated, because the target signal of the target frequency component is separated from the target resonance signal and the detection of the dispersion frequency shift is carried out for the target signal of the target frequency component, the target frequency component is related to the quantum dot device The frequency associated with the charge tunneling event in the quantum dot device is equivalent to filtering the influence of the noise part in the target resonance signal on the detection result, and only detecting the dispersion frequency of the target signal at the frequency part associated with the charge tunneling event in the quantum dot device. shift, so as to more accurately detect the state of silicon-based spin qubits in quantum dot devices. Therefore, it can solve the problem of low accuracy of measuring the state of silicon-based spin qubits through dispersion readout, and achieve the effect of improving the accuracy of measuring the state of silicon-based spin qubits through dispersion readout .

Description of drawings

FIG. 1 is a first schematic diagram of a signal separator according to an embodiment of the present application;

FIG. 2 is a second schematic diagram of a signal separator according to an embodiment of the present application;

Fig. 3 is a schematic diagram of a signal separator according to an optional embodiment of the present application;

Fig. 4 is a schematic diagram 1 of a measurement system of a qubit state according to an embodiment of the present application;

FIG. 5 is a second schematic diagram of a measurement system of a qubit state according to an embodiment of the present application;

6 is a schematic diagram of a working state of a microring resonator according to an embodiment of the present application;

FIG. 7 is a schematic diagram three of a qubit state measurement system according to an embodiment of the present application;

FIG. 8 is a schematic diagram 4 of a measurement system of a qubit state according to an embodiment of the present application;

FIG. 9 is a schematic diagram of detecting dispersion frequency shift through a resonance peak according to an embodiment of the present application;

FIG. 10 is a schematic diagram of a measurement circuit for qubit state readout of silicon-based spin qubit dispersion according to an embodiment of the present application;

FIG. 11 is a flowchart of a method for measuring a state of a qubit according to an embodiment of the present application;

Fig. 12 is a structural block diagram of a qubit state measurement device according to an embodiment of the present application.

Detailed ways

Embodiments of the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

It should be noted that the terms "first" and "second" in the description and claims of the present application and the above drawings are used to distinguish similar objects, but not necessarily used to describe a specific sequence or sequence.

Silicon-based spin qubit is a kind of qubit that is confined in silicon-based quantum dots and adopts spin encoding. Silicon-based quantum dots generally use isotope-purified ²⁸ Si (that is, silicon element) epitaxial layer as the carrier material, and the gate Therefore, a potential well structure with a size of only tens of nm (Nanometer, nanometer), called quantum dots, can be formed at a specific position on the heterogeneous interface or channel surface under the gate. Generally, by means of external magnetic field and microwave pulse excitation, the flipping of silicon-based spin qubits can be precisely regulated, thereby realizing various gate operations. At present, the fidelity of both single-bit and two-bit gates has exceeded the 99% fault tolerance threshold. The measurement of the flip state of the silicon-based spin qubit by means of dispersion readout can be performed by the point-to-point tunneling event generated when the silicon-based spin qubit is flipped as the dispersion frequency shift of the swept-frequency microwave, so as to pass through the detection device Show it off.

An embodiment of the present application provides a signal splitter. FIG. 1 is a schematic diagram of a signal splitter according to an embodiment of the present application. As shown in FIG. 1 , the signal splitter 102 includes: a first straight waveguide 104, a second straight waveguide 106 and ring waveguide 108,

The first straight waveguide 104 is connected to the second straight waveguide 106 through the ring waveguide 108;

The ring waveguide 108 includes: a first half ring waveguide 110, a second half ring waveguide 112, a first transmission waveguide 114 and a second transmission waveguide 116, wherein the first half ring waveguide 110 is embedded in the first straight waveguide The waveguide 104 forms a first coupling region, the second half-ring waveguide 112 is embedded in the second straight waveguide 106 to form a second coupling region, and the first transmission waveguide 114 is connected between the first half-ring waveguide 110 and the A first transmission zone is formed between the second half-ring waveguides 112, and the second transmission waveguide 116 is connected between the second half-ring waveguide 112 and the first half-ring waveguide 110 to form a second transmission zone;

The length parameter of the ring waveguide 108 is determined according to the target frequency component of the dispersion frequency shift during the measurement process of the silicon-based spin qubit state;

The signal separator 102 is configured to separate the target signal of the target frequency component from the received signal.

Through the above equipment, the signal separator using the above structure can separate the target signal of the target frequency component from the received signal, the target frequency component is the frequency associated with the charge tunneling event in the quantum dot device, which is equivalent to filtering In addition to the influence of the noise part in the target resonance signal on the detection results, only the dispersion frequency shift of the target signal at the frequency part associated with the charge tunneling event in the quantum dot device is detected, so as to detect the quantum dot device more accurately. Silicon-based spin qubit states. Therefore, it can solve the problem of low accuracy of measuring the state of silicon-based spin qubits through dispersion readout, and achieve the effect of improving the accuracy of measuring the state of silicon-based spin qubits through dispersion readout .

Optionally, in this embodiment, the above-mentioned signal separator can not only separate the target signal of the target frequency component, but also enhance the target signal, so that the silicon-based spin qubit The results of state measurements are more accurate.

Optionally, in this embodiment, each of the above-mentioned waveguides may be, but not limited to, be formed of a low-refractive-index cladding layer (such as silicon dioxide) and a high-refractive-index core layer (such as silicon, silicon nitride) when viewed from a cut plane.

Optionally, in this embodiment, the above-mentioned two straight waveguides can be but not limited to be arranged in parallel on the silicon substrate with a certain distance apart, and the above-mentioned two half-ring waveguides can be but not limited to be anti-symmetrical close to the straight waveguide and include The layer is partially embedded in the cladding of the straight waveguide, forming a first coupling region and a second coupling region.

In an exemplary embodiment, FIG. 2 is a second schematic diagram of a signal splitter according to an embodiment of the present application. As shown in FIG. 2, both the first transmission waveguide 114 and the second transmission waveguide 116 are in a meandering shape wherein, the first transmission waveguide 114 includes a first number of first meandering periods 202 connected in sequence, and the first meandering period 202 includes a first partial ring segment 204, a first straight line segment 206 connected in sequence , a first semi-annular segment 208, a second straight line segment 210 and a second partial annular segment 212; the second transmission waveguide 116 includes a second number of second meandering periods 214 connected in sequence, the second meandering period 214 comprises a third partial ring segment 216, a third straight segment 218, a second semi-ring segment 220, a fourth straight segment 222 and a fourth partial ring segment 224 connected in sequence; said first number is the same as said second number or different.

In an exemplary embodiment, the first number is the same as the second number, the radii of the first half-ring waveguide and the second half-ring waveguide are the same, the first partial ring segment, the first half-ring waveguide Two ring segments, the third ring segment, the fourth ring segment, the first half ring segment and the second half ring segment have the same radius, the first straight line segment, the first ring segment The lengths of the two straight line segments, the third straight line segment and the fourth straight line segment are the same.

In an optional embodiment, a structural example of the above-mentioned signal splitter is provided. FIG. 3 is a schematic diagram of a signal splitter according to an optional embodiment of the present application. As shown in FIG. 3 , the ring waveguide It is designed in the form of a combination of "semi-ring waveguide + meandering waveguide" to adapt to the increase in length caused by the reduction of frequency from the visible light frequency band to the microwave frequency band.

The signal splitter described above uses one input and two outputs. The input end is the In port, and the reflected signal transmitted by the previous stage is input to the signal splitter. The output terminals are the Through port and the Drop port respectively. All the reflected signal power when there is no inter-point charge tunneling event, and most of the reflected signal power during the inter-point charge tunneling event are output from the Through port. Only when the inter-point charge tunneling event occurs During the charge tunneling event between points, a small part of the frequency resonant reflection signal component is output from the drop port after resonance enhancement. The two output signals enter the IQ mixer through an amplifier respectively, and only the measurement signal is retained after demodulation. If the reflected signal output from the Drop port has two consecutive strong frequency responses in a narrow band, it indicates that the charge tunneling event between the auxiliary quantum dots has occurred.

The embodiment of the present application also provides a measurement system of the state of the qubit. FIG. 4 is a schematic diagram of a measurement system of the state of the qubit according to the embodiment of the application. As shown in FIG. 4 , the system includes: a signal source 402, A signal converter 404, a signal separator 406 and a detector 408, wherein the signal source 402 is connected to the signal converter 404, and the signal converter 404 is also connected to the quantum dot device 410 to be measured and the signal Between the separators 406, the signal separator 406 is connected to the detector 408;

The signal source 402 is configured to transmit an initial frequency sweep signal to the signal converter 404;

The signal converter 404 is configured to convert the initial sweep signal into an initial resonance signal and input it to the quantum dot device 410, and transmit the target resonance signal returned by the quantum dot device 410 to the signal separator 406;

The signal separator 406 is configured to separate a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event in the quantum dot device 410;

The detector 408 is configured to detect the dispersion frequency shift of the target signal, wherein the occurrence of the dispersion frequency shift in the signal output by the signal converter 404 indicates that the charge occurs in the quantum dot device 410. The charge tunneling event is used to characterize the silicon-based spin qubit state in the quantum dot device 410 .

Through the above system, the initial sweep signal is converted into an initial resonance signal by a signal converter and input to the quantum dot device, and the target resonance signal returned by the quantum dot device is transmitted to the signal separator, and then the target resonance signal is obtained from the target resonance signal through the signal separator The target signal of the target frequency component is separated, because the target signal of the target frequency component is separated from the target resonance signal and the detection of the dispersion frequency shift is carried out for the target signal of the target frequency component, the target frequency component is related to the quantum dot device The frequency associated with the charge tunneling event in the quantum dot device is equivalent to filtering the influence of the noise part in the target resonance signal on the detection result, and only detecting the dispersion frequency of the target signal at the frequency part associated with the charge tunneling event in the quantum dot device. shift, so as to more accurately detect the state of silicon-based spin qubits in quantum dot devices. Therefore, it can solve the problem of low accuracy of measuring the state of silicon-based spin qubits through dispersion readout, and achieve the effect of improving the accuracy of measuring the state of silicon-based spin qubits through dispersion readout .

Optionally, in this embodiment, the aforementioned quantum dot devices may be, but not limited to, silicon-based quantum dot devices. According to different confinement strategies, silicon-based quantum dot devices can be classified into SiMOS, Si/SiGe, FDSOI, and FinFET. SiMOS is Siliconmetal-oxide-semiconductor, that is, silicon metal-oxide-semiconductor. It is a laboratory-made quantum dot device. Quantum dots are formed in Si semiconductors (near the Si-SiO2 interface). Si/SiGe, or SiGe heterojunction, is another laboratory-fabricated quantum dot device in which the quantum dots are formed in Si wells (near the Si-SiGe barrier interface). FDSOI is Fully depleyed silicon on insulator, that is, fully depleted silicon on insulator, or directly called fully depleted SOI. It is a traditional semiconductor structure manufactured in industry and can be used as a quantum dot device. The quantum dot is located in the source, drain and gate contact. on the corner. FinFET is a Fin field-effect transistor, that is, a fin-type field-effect transistor. It is a traditional semiconductor structure manufactured in industry, and it can also be used as a quantum dot device. The quantum dot is located on the upper surface of the source, drain and gate contact. SiMOS and Si/SiGe are manufactured in laboratories to produce electron spin-encoded qubits, while FDSOI and FinFET are produced in industrial production lines to produce hole spin-encoded qubits.

Optionally, in this embodiment, the above-mentioned signal source may be, but not limited to, any signal source capable of transmitting frequency sweep signals. Combining with sending frequency-sweeping microwaves to the above-mentioned signal converter as an initial frequency-sweeping signal. Alternatively, the signal source can also be, but is not limited to, a single device capable of emitting frequency-sweeping microwaves.

Optionally, in this embodiment, the above-mentioned various signals may be, but not limited to, microwave signals.

Optionally, in this embodiment, the dispersion frequency shift of the signal output by the signal converter indicates that a charge tunneling event has occurred in the quantum dot device, and the charge tunneling event represents the silicon-based spin qubit in the quantum dot device state, so the qubit state can be measured by detecting the dispersion frequency shift of the target signal.

In an exemplary embodiment, FIG. 5 is a second schematic diagram of a qubit state measurement system according to an embodiment of the present application. As shown in FIG. 5 , the signal separator 406 includes: a microring resonator 502, wherein, The microring resonator 502 includes: a first straight waveguide 504, a second straight waveguide 506 and a ring waveguide 508, the first straight waveguide 504 is connected to the second straight waveguide 506 through the ring waveguide 508, the The input port 510 of the first straight waveguide 504 is connected with the signal converter 404, and the output port 512 of the second straight waveguide 506 is connected with the detector 408; the target frequency component is the microring resonator 502 the resonance condition;

The microring resonator 502 is configured to input the target resonance signal from the input port 510 and output the target signal satisfying the resonance condition from the output port 512 .

Optionally, in this embodiment, the microring resonator is a silicon-based photonics device. Structurally, the microring resonator is composed of a ring waveguide and a straight waveguide coupling. The ring waveguide can be one, or multiple parallel or series arrays. The straight waveguide can be one, called All-pass type, or it can be There are two, called Add-drop type.

Optionally, in this embodiment, the microring resonator is an Add-drop microring resonator, wherein the resonant frequency of the Add-drop microring resonator is the target frequency component; the first straight waveguide is an Add-drop The input port of the upper straight waveguide of the microring resonator is the In port of the upper straight waveguide; the second straight waveguide is the lower straight waveguide of the Add-drop microring resonator, and the input port is the Drop port of the lower straight waveguide.

The microring resonator has the advantages of low cost, small volume, compact structure, and high integration on the chip. In this embodiment, it is used as a filter. According to the frequency of the signal passed, the filter is divided into four types: low pass, high pass, band pass and band stop. Narrow specific frequency components are absorbed into the ring waveguide to achieve filtering. Fig. 6 is a schematic diagram of the working state of a microring resonator according to an embodiment of the present application. As shown in Fig. 6, the microring resonator uses an Add-drop structure and consists of two straight waveguides and a ring waveguide, wherein the ring The waveguide is divided into four functional areas: the first coupling area close to the up straight waveguide, the second coupling area close to the down straight waveguide, the first transmission area and the second transmission area between the first coupling area and the second coupling area . The microwave signal f is input from the In port of the upper straight waveguide. When it is transmitted to the first coupling area, part of the microwave power is coupled into the ring, and the remaining microwave power is output from the Through port. The microwaves coupled into the ring pass through the first transmission zone and reach the second coupling zone, where coupling occurs again. Part of the microwave power is coupled to the downlink straight waveguide and output from the Drop port, and the remaining power returns to the first coupling zone through the second transmission zone.

即（

表示有效折射率，L是环形波导总长度，m表示谐振级数，

是该级数对应的谐振波长，称该谐振波长对应的频率为谐振频率），则此时在第一耦合区发生谐振加强，其结果是环形波导中谐振频率功率增大，导致下路Drop端输出的谐振频率功率也随之增大。假设传输过程中没有损耗，如此往复多次，谐振频率将全部从下路直波导Drop端口输出，实现谐振频率与其他频率分量的分离。According to the resonance condition of the microring resonator, if the optical path difference of a specific wavelength component of the microwave signal is transmitted in the ring waveguide for one cycle is an integer multiple of the wavelength,

Right now(

Indicates the effective refractive index, L is the total length of the ring waveguide, m indicates the resonance order,

is the resonant wavelength corresponding to the series, and the frequency corresponding to the resonant wavelength is called the resonant frequency), then resonance enhancement occurs in the first coupling region at this time, and as a result, the power of the resonant frequency in the ring waveguide increases, resulting in the drop terminal The output resonant frequency power also increases accordingly. Assuming that there is no loss in the transmission process, and so many times, the resonant frequency will all be output from the Drop port of the down-channel straight waveguide, realizing the separation of the resonant frequency from other frequency components.

In an exemplary embodiment, the resonant frequency of the microring resonator is within the dispersion frequency shift range of the signal converter, and the full width at half maximum of the microring resonator is smaller than the bandwidth of the signal converter.

Optionally, in this embodiment, the notch characteristic of the microring resonator is used to absorb and output the frequency response associated with the charge tunneling event between points. Taking the signal converter as an LC resonator as an example, the above-mentioned microring resonator The resonator meets the following two requirements: one is that the resonant frequency of the microring resonator is within the dispersion frequency shift range of the LC resonator, and the other is that the full width at half maximum of the microring resonator is much smaller than the bandwidth of the LC resonator.

In an exemplary embodiment, FIG. 7 is a schematic diagram three of a qubit state measurement system according to an embodiment of the present application. As shown in FIG. 7, the ring waveguide 508 includes: a first half ring waveguide 702, a second A half-ring waveguide 704, a first transmission waveguide 706 and a second transmission waveguide 708, wherein the first half-ring waveguide 702 is embedded in the first straight waveguide 504 to form a first coupling region, and the second half-ring waveguide 704 is embedded in The second straight waveguide 506 forms a second coupling region, and the first transmission waveguide 706 connects between the first half-ring waveguide 702 and the second half-ring waveguide 704 to form a first transmission region. Two transmission waveguides 708 are connected to form a second transmission area between the second half ring waveguide 704 and the first half ring waveguide 702; the length parameter of the ring waveguide 508 is determined according to the target frequency component.

Optionally, in this embodiment, the shape and arrangement of each transmission waveguide can be changed according to requirements.

Optionally, in this embodiment, the length parameter of the ring waveguide may include, but is not limited to, the length and curvature of each part in the ring waveguide. For example: the radius of each semi-ring waveguide, the radius of the ring part of each transmission waveguide, the length of the straight part and so on.

In an exemplary embodiment, both the first transmission waveguide and the second transmission waveguide are meander-shaped waveguides, wherein the first transmission waveguide includes a first number of first meandering periods connected in sequence ; the second transmission waveguide includes a second number of second serpentine periods connected in sequence; the first number is the same as or different from the second number.

Optionally, in this embodiment, through the above-mentioned serpentine-shaped waveguide with a certain number of serpentine periods, a serpentine-like arrangement structure is formed in the first transmission area and the second transmission area, on the one hand, it can form a signal transmission , on the other hand, it can save the area occupied by the structure.

In an exemplary embodiment, the first meandering cycle includes a first partial ring segment, a first straight segment, a first half ring segment, a second straight segment and a second partial ring segment connected in sequence; the second The serpentine cycle includes a third partial ring segment, a third straight line segment, a second half ring segment, a fourth straight line segment and a fourth partial ring segment connected in sequence.

Optionally, in this embodiment, the first partial ring segment, the second partial ring segment, the third partial ring segment, and the fourth partial ring segment are all quarter ring segments.

In an exemplary embodiment, the first number is the same as the second number, the radii of the first half-ring waveguide and the second half-ring waveguide are the same, the first partial ring segment, the first half-ring waveguide Two ring segments, the third ring segment, the fourth ring segment, the first half ring segment and the second half ring segment have the same radius, the first straight line segment, the first ring segment The lengths of the two straight line segments, the third straight line segment and the fourth straight line segment are the same.

Optionally, in this embodiment, through the configuration of the above parameters, the structures in the first transmission waveguide and the second transmission waveguide are arranged regularly and symmetrically.

In an exemplary embodiment, FIG. 8 is a schematic diagram four of a qubit state measurement system according to an embodiment of the present application. As shown in FIG. 8, the detector 408 includes: an amplifier 802 and an IQ mixer 804, Wherein, the amplifier 802 is connected between the signal splitter 406 and the IQ mixer 804; the IQ mixer 804 is used to output the resonant peak of the target signal; and according to the resonant peak detection The dispersion frequency shift of the target signal occurs.

Optionally, in this embodiment, it is possible, but not limited to, to detect the dispersion frequency shift of the target signal through the formant peak. FIG. 9 is a schematic diagram of detecting the dispersion frequency shift through the formant peak according to the embodiment of the present application, as shown in FIG. 9 : When the target signal has a dispersion frequency shift, the resonance peak will shift, that is, if the resonance peak shifts, it can be determined that the target signal has a dispersion frequency shift.

In an exemplary embodiment, the signal converter includes: a grid reflectometer, or an LC resonator equivalent to the grid reflectometer.

Optionally, in this embodiment, the dispersion readout uses a Gate-reflectometry (GR), and the GR is essentially an LC resonator, which can represent the point-to-point tunneling event as the dispersion frequency of the swept microwave shift, does not involve embedded charge sensors, has obvious scalability advantages, and is more robust to temperature, and can work at K-level temperatures (Temperature K, Kelvin temperature).

Optionally, in this embodiment, the grid reflectometer may include, but is not limited to, chip inductors and grid parasitic capacitances, and include an auxiliary quantum dot serving as a variable impedance load for the resonator. For example: the auxiliary quantum dot is located on the quantum dot device and defined by the gate of the quantum dot device, the chip inductor is located on the printed circuit board (PCB) that fixes the quantum dot device, and the chip inductor and the auxiliary quantum dot are bonded through the wire combined connection.

Optionally, in this embodiment, it may be, but not limited to, that the bias gate DC voltage of the quantum dot device causes the charge in the quantum dot of the quantum dot device to undergo spin-selective point-to-point tunneling, which is associated with the charge transition The additional quantum capacitance of the above-mentioned signal converter causes a dispersion frequency shift.

Optionally, in this embodiment, an amplifier and an IQ mixer may also be connected to the Through port of the microring resonator to detect the resonant peak of the signal output from the Through port. Fig. 10 is a schematic diagram of a measurement circuit of a qubit state for silicon-based spin qubit dispersion readout according to an embodiment of the present application. As shown in Fig. 10, the equivalent LC resonator and quantum The point device connection, the voltage source and the microwave source as the signal source provide the frequency-sweeping microwave for the LC resonator and the quantum dot device through the biaser, and the directional coupler transmits the returned signal to the In port of the microring resonator, and the microring resonator The drop port of the microring resonator is connected to a set of amplifiers and IQ mixers, and the through port of the microring resonator is connected to another set of amplifiers and IQ mixers.

For the dispersion readout scheme, starting from the improvement of the measurement circuit, an Add-drop microring resonator branch is introduced to resonate and absorb a certain frequency component of the reflected signal that has a dispersion frequency shift into the ring waveguide, and output it from the drop end. The notch characteristic of the microring resonator is used to reduce the influence of background noise on the thermal broadening of the frequency component, and whether the spin-related charge tunneling event occurs is judged according to whether the output of the drop terminal has a frequency response.

In this embodiment, a method for measuring the qubit state running on the above-mentioned mobile terminal is provided. FIG. 11 is a flowchart of a method for measuring the state of the qubit according to the embodiment of the present application. As shown in FIG. 11 , the process includes Follow the steps below:

Step S1102, converting the initial frequency sweep signal into an initial resonance signal and inputting it to the quantum dot device to be measured;

Step S1104, acquiring the target resonance signal returned by the quantum dot device;

Step S1106, separating a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event in the quantum dot device;

Step S1108, detecting the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the separated signal indicates that the charge tunneling event has occurred in the quantum dot device, and the charge tunneling event is used for Characterizing the silicon-based spin qubit state within the quantum dot device.

Through the above steps, the initial sweep signal is converted into an initial resonance signal and input to the quantum dot device to obtain the target resonance signal returned by the quantum dot device, and then the target signal of the target frequency component is separated from the target resonance signal, because the target frequency The target signal of the component is separated from the target resonance signal, and the detection of the dispersion frequency shift is carried out for the target signal of this part of the target frequency component. The target frequency component is the frequency associated with the charge tunneling event in the quantum dot device, which is equivalent to filtering out The impact of the noise part in the target resonance signal on the detection results, only detect the dispersion frequency shift of the target signal in the frequency part associated with the charge tunneling event in the quantum dot device, so as to more accurately detect the silicon in the quantum dot device Spin-based qubit states. Therefore, it can solve the problem of low accuracy of measuring the state of silicon-based spin qubits through dispersion readout, and achieve the effect of improving the accuracy of measuring the state of silicon-based spin qubits through dispersion readout .

In the technical solution provided by the above step S1102, the above-mentioned initial frequency sweep signal may be but not limited to frequency sweep microwave, which may be but not limited to be synthesized by a voltage signal sent by a voltage source and a microwave signal sent by a microwave source through a biaser Sweep microwave. Or a frequency-swept microwave from a signal source.

Optionally, in this embodiment, the above-mentioned initial resonance signal may be obtained, but not limited to, by resonating the initial frequency sweep signal at the resonant frequency of the grid reflectometer and the grid reflectometer.

Optionally, in this embodiment, charge tunneling events may occur in the above-mentioned quantum dot device, but not limited to, the above-mentioned quantum dot device may, but not limited to, be excited by an external magnetic field and microwave pulses to achieve precise control of the silicon-based self- Spin qubit flipping and various gate operations, which can include, but are not limited to: SiMOS, Si or SiGe, FDSOI, and FinFET, among others.

In the technical solution provided in the above step S1104, the above target resonance signal can be obtained, but not limited to, based on the point-to-point tunneling event of the quantum dot device, for example: if the capacitance of the signal converter is +2 (positive 2), the quantum dot The additional capacitance generated by inter-point tunneling events during the period is -1 (negative 1), and the additional capacitance generated by inter-point tunneling events during the quantum dot period is superimposed on the capacitance of the signal converter, the total capacitance decreases, and the frequency increases. Target resonance signal returned by the signal converter.

In the technical solution provided by the above step S1106, the above target frequency component is the frequency associated with the charge tunneling event in the quantum dot device. That is to say, the above-mentioned target frequency component may be determined according to the frequency associated with the charge tunneling event, but is not limited to it.

，目标频率分量为

为例，目标频率分量为

必定落入信号转换器的色散频移范围为

，也就是说，根据信号转换器的色散频移范围为

即可确定目标频率分量

。Optionally, in this embodiment, a method for determining the target frequency component is provided, where the dispersion frequency shift range of the signal converter is

, the target frequency component is

As an example, the target frequency component is

The range of dispersion frequency shifts that must fall into the signal converter is

, that is, according to the dispersion frequency shift range of the signal converter is

The target frequency component can be determined

.

In an exemplary embodiment, the target signal of the target frequency component may be separated from the target resonance signal in the following manner, but not limited to: extracting the signal of the target frequency component from the target resonance signal to obtain a reference signal; performing signal enhancement on the reference signal to obtain the target signal.

Optionally, in this embodiment, the extraction and enhancement of the signal of the target frequency component can not only detect the dispersion frequency shift of the signal of the target frequency component in a targeted manner, but also improve the signal-to-noise ratio of this part of the signal, so that the detection The process is more accurate and efficient.

（

表示有效折射率，

是环形波导总长度，

表示谐振级数，

是该级数对应的谐振波长，称该谐振波长对应的频率为谐振频率），则此时在发生谐振加强，其结果是微环谐振器的环形波导中的谐振频率功率增大，导致输出的谐振频率功率也随之增大。假设传输过程中没有损耗，如此往复多次，谐振频率将全部从端口输出，实现谐振频率与其他频率分量的分离。Optionally, in this embodiment, a method for extracting a target signal is provided. Take extracting a target signal through a microring resonator as an example. According to the resonance condition of the microring resonator, if a specific wavelength component of the microwave signal is in The optical path difference for one round of transmission in the ring waveguide is an integer multiple of the wavelength, that is

(

is the effective refractive index,

is the total length of the ring waveguide,

Indicates the resonance order,

is the resonant wavelength corresponding to the series, and the frequency corresponding to the resonant wavelength is called the resonant frequency), then resonance strengthening occurs at this time, and the result is that the resonant frequency power in the ring waveguide of the microring resonator increases, resulting in the output The resonant frequency power also increases accordingly. Assuming that there is no loss in the transmission process, and so many times, the resonant frequency will all be output from the port, realizing the separation of the resonant frequency from other frequency components.

In an exemplary embodiment, the target signal of the target frequency component may be separated from the target resonance signal by, but not limited to: separating the target frequency component from the target resonance signal by a microring resonator The target signal, wherein the microring resonator includes: a first straight waveguide, a second straight waveguide and a ring waveguide, the first straight waveguide is connected to the second straight waveguide through the ring waveguide, the The input port of the first straight waveguide is used to input the target resonance signal, and the output port of the second straight waveguide is used to output the target signal satisfying the resonance condition of the microring resonator, and the resonance condition is The target frequency component.

Optionally, in this embodiment, the resonance condition of the microring resonator is the target frequency component, so that the target signal of the target frequency component is separated from the target resonance signal.

In an exemplary embodiment, before the target signal of the target frequency component is separated from the target resonance signal by the microring resonator, the ring waveguide may be formed in the following manner, but not limited to: Determine the length parameter of the ring waveguide according to the target frequency component, wherein the ring waveguide includes: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide, the first The half-ring waveguide is embedded in the first straight waveguide to form a first coupling region, the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to the first half-ring waveguide A first transmission zone is formed between the waveguide and the second half-ring waveguide, and the second transmission waveguide connection forms a second transmission zone between the second half-ring waveguide and the first half-ring waveguide.

Optionally, in this embodiment, the length parameter of the ring waveguide may be, but not limited to, determined according to the target frequency component.

Optionally, in this embodiment, the above-mentioned coupling region may be, but not limited to, formed by embedding a half-ring waveguide into a straight waveguide, and it may be, but not limited to, used to control the full width at half maximum of the resonant peak.

Optionally, in this embodiment, the above-mentioned transmission region is formed by a meander-shaped waveguide, which can be used but not limited to control the resonance frequency.

In an exemplary embodiment, the length parameter of the ring waveguide may be determined according to the target frequency component in the following manner: obtain the dispersion frequency shift range of the signal converter, wherein the signal converter is used to convert the The charge tunneling event in the quantum dot device is converted into the dispersion frequency shift of the signal; according to the material properties of the microring resonator, the target frequency component is selected from the dispersion frequency shift range as the microring resonator a resonant frequency, wherein the full width at half maximum of the microring resonator having the resonant frequency is smaller than the bandwidth of the signal converter; the waveguide length of the ring waveguide is calculated according to the target frequency component; the waveguide length of the ring waveguide is calculated according to the waveguide length and The deployment information of the microring resonator determines the radius of the semi-ring waveguide, the radius of the ring segment, the length of the straight line segment and the number of meandering cycles as the length parameter; wherein, the first transmission waveguide and the second transmission waveguide are both A meander-shaped waveguide, the first transmission waveguide includes a first number of first meander periods connected in sequence, the second transmission waveguide includes a second number of second meander periods connected in sequence, the first The number is the same as or different from the second number, and the first meandering period includes a first partial ring segment, a first straight line segment, a first semi-ring segment, a second straight line segment and a second partial ring segment connected in sequence, so The second meandering period includes a third partial ring segment, a third straight line segment, a second semi-ring segment, a fourth straight line segment and a fourth partial ring segment connected in sequence; wherein, the radius of the semi-ring waveguide is the first The radii of the half-ring waveguide and the second half-ring waveguide, the ring segment radii are the first partial ring segment, the second partial ring segment, the third partial ring segment, and the fourth partial ring segment, The radius of the first semi-annular segment and the second semi-annular segment, the length of the straight line segment is the first straight line segment, the second straight line segment, the third straight line segment and the fourth straight line The length of the segment, the number of meandering cycles is the sum of the first number and the second number.

Optionally, in this embodiment, the above-mentioned signal converter is used to convert the charge tunneling event in the quantum dot device into the dispersion frequency shift of the signal. The above-mentioned signal converter may be, but not limited to, GR or an LC resonator equivalent to GR.

对隧穿事件发生期间的色散频移进行时间积分，获得相位响应：

，其中

为LC谐振器的品质因子。根据相位响应获得附加量子电容

可反向得到色散频移的范围。Optionally, in this embodiment, the dispersion frequency shift range of the above-mentioned signal converter can be determined according to different tunneling states, for example, in order to distinguish different tunneling states during actual measurement, the microwave fixed at

Time-integrate the dispersion frequency shift during the tunneling event to obtain the phase response:

,in

is the quality factor of the LC resonator. Additional Quantum Capacitance Obtained from Phase Response

The range of dispersion frequency shift can be obtained inversely.

指的是定义辅助量子点的柱塞栅极寄生电容

则LC谐振器的固有谐振频率为：

In an optional embodiment, a method for obtaining the dispersion frequency shift range of the signal converter is provided. When there is no charge tunneling between points, the capacitance

refers to the parasitic capacitance of the plunger gate that defines the auxiliary quantum dot

Then the natural resonant frequency of the LC resonator is:

是贴片电感器的电感。in,

is the inductance of the chip inductor.

电容C包括了寄生电容

和量子电容

则LC谐振器的谐振频率变为：

When charge tunneling between points occurs, causing additional quantum capacitance associated with charge transitions

Capacitor C includes the parasitic capacitance

and quantum capacitance

The resonant frequency of the LC resonator then becomes:

。It can be seen that the LC resonant frequency undergoes a dispersion frequency shift. Once the tunneling event is completed, the resonant frequency of the LC resonator will return to the natural resonant frequency, and the duration is determined by the charge mobility and the effective noise temperature, generally in the order of ms (millisecond, millisecond). In order to distinguish different tunneling states during actual measurement, the frequency-sweeping microwave is fixed at

.

为例，微环谐振器的谐振频率处于LC谐振器的色散频移

范围内。Optionally, in this embodiment, the resonant frequency of the above-mentioned microring resonator may be, but not limited to, within the dispersion frequency shift range of the signal converter, for example: the dispersion frequency shift range of the signal converter is

As an example, the resonant frequency of the microring resonator is at the dispersion frequency shift of the LC resonator

within range.

Optionally, in this embodiment, the full width at half maximum of the microring resonator may be, but not limited to, smaller than the bandwidth of the signal converter.

In an optional embodiment, a method for obtaining the full width at half maximum of the microring resonator is provided. In the case of excluding dispersion, the full width at half maximum of the microring resonator is:

分别是第一耦合区和第二耦合区的透射系数，

表示有效折射率，

是环形波导总长度，m表示谐振级数，

是该级数对应的谐振波长即该谐振波长对应的频率为谐振频率。Among them, α is the amplitude loss factor of the microwave signal traveling along the ring waveguide for one cycle,

are the transmission coefficients of the first coupling region and the second coupling region, respectively,

is the effective refractive index,

is the total length of the ring waveguide, m represents the resonance series,

It is the resonant wavelength corresponding to the series, that is, the frequency corresponding to the resonant wavelength is the resonant frequency.

（

表示有效折射率，L是环形波导总长度，m表示谐振级数，

是该级数对应的谐振波长，称该谐振波长对应的频率为谐振频率）。Optionally, in this embodiment, the waveguide length of the above-mentioned ring waveguide may be calculated according to the target frequency component, for example, if the optical path difference of a specific wavelength component of the microwave signal traveling in the ring waveguide is Integer multiples of the wavelength, that is,

(

Indicates the effective refractive index, L is the total length of the ring waveguide, m indicates the resonance order,

is the resonance wavelength corresponding to the series, and the frequency corresponding to the resonance wavelength is called the resonance frequency).

The relationship between the resonant frequency of the mth resonant series and the total length of the ring waveguide is:

where c is the speed of light.

Optionally, in this embodiment, the length of each part of the signal converter can be determined according to the resonant frequency of the signal separator, for example: assuming that the resonant frequency of the LC resonator (that is, the signal converter) has been fixed, select The resonant frequency of the ring resonator (that is, the signal separator) is within the dispersion frequency shift range of the LC resonator (generally larger than the kHz order), determine the total length of the combination of "semi-ring waveguide + meandering waveguide" (resonant series is desirable 1, the total length is the minimum at this time). After removing the two half-ring waveguide lengths, the remaining length is evenly distributed to the first transmission area and the second transmission area.

=890fF，产生的LC谐振器的谐振频率

=266.744MHz，品质因子Q=38；观察到的相位响应ΔΦ=2.2mrad，计算得到附加的量子电容

=-0.016fF，可以估计色散频移

≈266.747MHz，即向高频偏移3kHz，为例：In an optional embodiment, a determination process of length parameters is provided, based on the circuit parameters of GR: chip inductor inductance L=400nH, parasitic capacitance

=890fF, the resonant frequency of the LC resonator produced by

=266.744MHz, quality factor Q=38; the observed phase response ΔΦ=2.2mrad, the additional quantum capacitance is calculated

=-0.016fF, the dispersion frequency shift can be estimated

≈266.747MHz, that is, shifting to high frequency by 3kHz, for example:

随频率会发生变化，这里固定为

≈2。Assuming that the cladding and core materials are silicon dioxide and silicon nitride respectively, the refractive indices are n (silicon dioxide) = 1.5 and n (silicon nitride) = 2.5, due to the effective refractive index

It will change with the frequency, here it is fixed as

≈2.

=266.746MHz，假设振幅损耗因子α=

，透射系数

，则半高全宽

，满足设计要求。Selecting the resonant frequency of the microring resonator

=266.746MHz, assuming the amplitude loss factor α=

, the transmission coefficient

, then the full width at half height

,Meet the design requirements.

计算得到“半环形波导+蜿蜒波导”组合的总长度L=397.629mm。要在一块2cm×2cm的芯片上排列该组合，可以取耦合区的半环形波导半径r1=0.01mm，蜿蜒波导中的环形段半径r2=0.4mm，直线段长度s2=7.779mm，蜿蜒周期22周，整体占据面积1.809cm×1.762cm。周边剩余芯片区域可用于分布两个直波导以及端口。According to the resonant frequency

The total length L=397.629mm of the combination of "semi-ring waveguide + meander waveguide" is calculated. To arrange this combination on a 2cm×2cm chip, the radius of the half-ring waveguide in the coupling region r1=0.01mm, the radius of the ring section in the meandering waveguide r2=0.4mm, the length of the straight line s2=7.779mm, and the meandering waveguide The cycle is 22 weeks, and the overall occupied area is 1.809cm×1.762cm. The remaining chip area around the perimeter can be used to distribute the two straight waveguides as well as the ports.

Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of software plus a necessary general-purpose hardware platform, and of course also by hardware, but in many cases the former is better implementation. Based on this understanding, the essence of the technical solution of this application or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products are stored in a storage medium (such as ROM/RAM, disk, CD-ROM), including several instructions to enable a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present application.

In this embodiment, a device for measuring the state of qubits is also provided, and the device is used to implement the above embodiments and preferred implementation modes, and those that have already been described will not be described again. As used below, the term "module" may be a combination of software and/or hardware that realizes a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementations in hardware, or a combination of software and hardware are also possible and contemplated.

Fig. 12 is a structural block diagram of a qubit state measuring device according to an embodiment of the present application. As shown in Fig. 12, the device includes:

The input module 1202 is used to convert the initial frequency sweep signal into an initial resonance signal and input it to the quantum dot device to be measured;

An acquisition module 1204, configured to acquire the target resonance signal returned by the quantum dot device;

A separation module 1206, configured to separate a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event in the quantum dot device;

The detection module 1208 is configured to detect the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the separated signal indicates that the charge tunneling event occurs in the quantum dot device, and the charge tunneling Events are used to characterize the silicon-based spin qubit state within the quantum dot device.

Through the above-mentioned device, the initial frequency sweep signal is converted into an initial resonance signal and input to the quantum dot device to obtain the target resonance signal returned by the quantum dot device, and then the target signal of the target frequency component is separated from the target resonance signal. Since the target frequency The target signal of the component is separated from the target resonance signal, and the detection of the dispersion frequency shift is carried out for the target signal of this part of the target frequency component. The target frequency component is the frequency associated with the charge tunneling event in the quantum dot device, which is equivalent to filtering out The impact of the noise part in the target resonance signal on the detection results, only detect the dispersion frequency shift of the target signal in the frequency part associated with the charge tunneling event in the quantum dot device, so as to more accurately detect the silicon in the quantum dot device Spin-based qubit states. Therefore, it can solve the problem of low accuracy of measuring the state of silicon-based spin qubits through dispersion readout, and achieve the effect of improving the accuracy of measuring the state of silicon-based spin qubits through dispersion readout .

In an exemplary embodiment, the separation module includes:

an extraction unit, configured to extract a signal of a target frequency component from the target resonance signal to obtain a reference signal;

The enhancement unit is configured to perform signal enhancement on the reference signal to obtain the target signal.

In an exemplary embodiment, the separation module is used for:

The target signal of the target frequency component is separated from the target resonance signal by a microring resonator, wherein the microring resonator includes: a first straight waveguide, a second straight waveguide and a ring waveguide, the The first straight waveguide is connected to the second straight waveguide through the ring waveguide, the input port of the first straight waveguide is used to input the target resonance signal, and the output port of the second straight waveguide is used to output the The target signal of the resonance condition of the microring resonator, the resonance condition being the target frequency component.

In an exemplary embodiment, the device also includes:

A determining module, configured to determine a length parameter of the ring waveguide according to the target frequency component, wherein the ring waveguide includes: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide , the first half-ring waveguide is embedded in the first straight waveguide to form a first coupling region, the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to the A first transmission area is formed between the first half-ring waveguide and the second half-ring waveguide, and the second transmission waveguide is connected to form a second half-ring waveguide between the second half-ring waveguide and the first half-ring waveguide. transmission area.

In an exemplary embodiment, the determination module includes:

An acquisition unit, configured to acquire the dispersion frequency shift range of the signal converter, wherein the signal converter is used to convert the charge tunneling event in the quantum dot device into the dispersion frequency shift of the signal;

a selection unit, configured to select the target frequency component from the dispersion frequency shift range according to the material properties of the microring resonator as the resonant frequency of the microring resonator, wherein the The full width at half maximum of the microring resonator is less than the bandwidth of the signal converter;

a calculation unit, configured to calculate the waveguide length of the ring waveguide according to the target frequency component;

A determination unit, configured to determine the radius of the semi-ring waveguide, the radius of the ring segment, the length of the straight line segment and the number of meandering cycles as the length parameter according to the length of the waveguide and the deployment information of the microring resonator; wherein the first Both the transmission waveguide and the second transmission waveguide are meander-shaped waveguides, the first transmission waveguide includes a first number of first meandering periods connected in sequence, and the second transmission waveguide includes a second number of first meandering periods connected in sequence The second meandering cycle, the first number is the same as or different from the second number, the first meandering cycle includes a first ring segment, a first straight line segment and a second ring segment connected in sequence, the The circular orientation of the first ring segment is opposite to that of the second ring segment, and the second meandering period includes a third ring segment, a second straight line segment and a fourth ring segment connected in sequence, and the third ring segment is connected to the second ring segment. The ring direction of the fourth ring segment is opposite; wherein, the radius of the half ring waveguide is the radius of the first half ring waveguide and the second half ring waveguide, the ring segment radius is the first ring segment, and the The second ring segment, the radius of the third ring segment and the fourth ring segment, the length of the straight segment is the length of the first straight segment and the second straight segment, and the number of meandering cycles is the The sum of the first quantity and the second quantity.

It should be noted that the above-mentioned modules can be realized by software or hardware. For the latter, it can be realized by the following methods, but not limited to this: the above-mentioned modules are all located in the same processor; or, the above-mentioned modules can be combined in any combination The forms of are located in different processors.

Embodiments of the present application also provide a computer-readable storage medium, in which a computer program is stored, wherein the computer program is configured to perform the steps in any one of the above method embodiments when running.

In an exemplary embodiment, the above-mentioned computer-readable storage medium may include but not limited to: U disk, read-only memory (Read-Only Memory, ROM for short), random access memory (Random Access Memory, RAM for short) , mobile hard disk, magnetic disk or optical disk and other media that can store computer programs.

An embodiment of the present application also provides an electronic device, including a memory and a processor, where a computer program is stored in the memory, and the processor is configured to run the computer program to perform the steps in any one of the above method embodiments.

In an exemplary embodiment, the electronic device may further include a transmission device and an input and output device, wherein the transmission device is connected to the processor, and the input and output device is connected to the processor.

For specific examples in this embodiment, reference may be made to the examples described in the foregoing embodiments and exemplary implementation manners, and details will not be repeated here in this embodiment.

Obviously, those skilled in the art should understand that each module or each step of the above-mentioned application can be realized by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed in a network composed of multiple computing devices In fact, they can be implemented in program code executable by a computing device, and thus, they can be stored in a storage device to be executed by a computing device, and in some cases, can be executed in an order different from that shown here. Or described steps, or they are fabricated into individual integrated circuit modules, or multiple modules or steps among them are fabricated into a single integrated circuit module for implementation. As such, the present application is not limited to any specific combination of hardware and software.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the principles of this application shall be included within the scope of protection of this application.

Claims (19)

1. A signal splitter, is characterized in that, comprises: the first straight waveguide, the second straight waveguide and ring waveguide, The first straight waveguide is connected to the second straight waveguide through the ring waveguide; The ring waveguide includes: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide, wherein the first half ring waveguide is embedded in the first straight waveguide to form a first coupling region , the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to form a first transmission between the first half-ring waveguide and the second half-ring waveguide zone, the second transmission waveguide is connected to form a second transmission zone between the second half-ring waveguide and the first half-ring waveguide, the first transmission waveguide and the second transmission waveguide are meandering shaped waveguide; The length parameter of the ring waveguide is determined according to the target frequency component of the dispersion frequency shift during the measurement process of the silicon-based spin qubit state; The signal separator is used to separate the target signal of the target frequency component from the received signal. 2. The signal splitter according to claim 1, characterized in that, The first transmission waveguide includes a first number of first meandering periods connected in sequence, and the first meandering period includes a first partial ring segment, a first straight line segment, a first semi-ring segment, a second straight line segment and the second part of the ring segment; The second transmission waveguide includes a second number of second meandering periods connected in sequence, and the second meandering period includes a third partial ring segment, a third straight line segment, a second semi-ring segment, a fourth Straight line segment and the fourth part ring segment; The first quantity is the same as or different from the second quantity. 3. The signal splitter according to claim 2, wherein the first number is the same as the second number, and the radius of the first half-ring waveguide and the second half-ring waveguide are the same, so The radii of the first partial annular segment, the second partial annular segment, the third partial annular segment, the fourth partial annular segment, the first semi-annular segment and the second semi-annular segment are the same, so The lengths of the first straight line segment, the second straight line segment, the third straight line segment and the fourth straight line segment are the same. 4. A measurement system of a qubit state, characterized in that, comprising: a signal source, a signal converter, a signal splitter and a detector, wherein, The signal source is connected to the signal converter, and the signal converter is also connected between the quantum dot device to be measured and the signal separator, and the signal separator is connected to the detector; The signal source is used to transmit an initial frequency sweep signal to the signal converter; The signal converter is used to convert the initial sweep signal into an initial resonance signal and input it to the quantum dot device, and transmit the target resonance signal returned by the quantum dot device to the signal separator; The signal separator is configured to separate a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event in the quantum dot device; The detector is configured to detect the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the signal output by the signal converter indicates that the charge tunneling event occurs in the quantum dot device, The charge tunneling event is used to characterize the silicon-based spin qubit state within the quantum dot device; Wherein, the signal splitter includes: a microring resonator, wherein the microring resonator includes: a first straight waveguide, a second straight waveguide and a ring waveguide, The first straight waveguide is connected to the second straight waveguide through the ring waveguide, the input port of the first straight waveguide is connected to the signal converter, and the output port of the second straight waveguide is connected to the detection device connection; The target frequency component is a resonance condition of the microring resonator; The microring resonator is configured to input the target resonance signal from the input port, and output the target signal satisfying the resonance condition from the output port. 5. The system according to claim 4, wherein the resonant frequency of the microring resonator is within the dispersion frequency shift range of the signal converter, and the full width at half maximum of the microring resonator is smaller than the bandwidth of the signal converter. 6. The system according to claim 4, wherein the ring waveguide comprises: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide, wherein, The first half-ring waveguide is embedded in the first straight waveguide to form a first coupling region, the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to the A first transmission region is formed between the first half ring waveguide and the second half ring waveguide, and the second transmission waveguide is connected to form a second transmission region between the second half ring waveguide and the first half ring waveguide district; The length parameter of the ring waveguide is determined according to the target frequency component. 7. The system according to claim 6, wherein the first transmission waveguide and the second transmission waveguide are meander-shaped waveguides, wherein, said first transmission waveguide comprises a first number of first serpentine periods connected in sequence; said second transmission waveguide comprises a second number of second serpentine periods connected in sequence; The first quantity is the same as or different from the second quantity. 8. The system of claim 7, wherein the first serpentine cycle comprises sequentially connected first partial circular segment, first straight segment, first semi-circular segment, second straight segment and second partial Ring segment; The second meandering cycle includes a third partial ring segment, a third straight line segment, a second half ring segment, a fourth straight line segment and a fourth partial ring segment connected in sequence. 9. The system according to claim 8, wherein the first number is the same as the second number, the radius of the first half-ring waveguide and the second half-ring waveguide are the same, and the first half-ring waveguide has the same radius as the second half-ring waveguide. A portion of the annular segment, the second partial annular segment, the third partial annular segment, the fourth partial annular segment, the first semi-annular segment and the second semi-annular segment have the same radius, and the first semi-annular segment The straight line segment, the second straight line segment, the third straight line segment and the fourth straight line segment have the same length. 10. The system according to claim 4, wherein the detector comprises: an amplifier and an IQ mixer, wherein, the amplifier is connected between the demultiplexer and the IQ mixer; The IQ mixer is used to output the resonance peak of the target signal; and detect the dispersion frequency shift of the target signal according to the resonance peak. 11. The system according to claim 4, wherein the signal converter comprises: a grid reflectometer, or an LC resonator equivalent to the grid reflectometer. 12. A measurement method of a qubit state, characterized in that, the measurement method is applied to the measurement system of the qubit state described in any one of claims 4 to 11, and the measurement method comprises: Convert the initial frequency sweep signal into an initial resonance signal and input it to the quantum dot device to be measured; Obtain the target resonance signal returned by the quantum dot device; separating a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event within the quantum dot device; Detecting the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the separated signal indicates that the charge tunneling event has occurred in the quantum dot device, and the charge tunneling event is used to characterize the Silicon-based spin qubit states within quantum dot devices. 13. The method according to claim 12, wherein said separating the target signal of the target frequency component from the target resonance signal comprises: extracting a signal of a target frequency component from the target resonance signal to obtain a reference signal; performing signal enhancement on the reference signal to obtain the target signal. 14. The method according to claim 12, wherein said separating the target signal of the target frequency component from the target resonance signal comprises: The target signal of the target frequency component is separated from the target resonance signal by a microring resonator, wherein the microring resonator includes: a first straight waveguide, a second straight waveguide and a ring waveguide, the The first straight waveguide is connected to the second straight waveguide through the ring waveguide, the input port of the first straight waveguide is used to input the target resonance signal, and the output port of the second straight waveguide is used to output the The target signal of the resonance condition of the microring resonator, the resonance condition being the target frequency component. 15. The method according to claim 14, wherein, before the target signal of the target frequency component is separated from the target resonance signal by the microring resonator, the method further comprises: Determine the length parameter of the ring waveguide according to the target frequency component, wherein the ring waveguide includes: a first half ring waveguide, a second half ring waveguide, a first transmission waveguide and a second transmission waveguide, the first The half-ring waveguide is embedded in the first straight waveguide to form a first coupling region, the second half-ring waveguide is embedded in the second straight waveguide to form a second coupling region, and the first transmission waveguide is connected to the first half-ring waveguide A first transmission zone is formed between the waveguide and the second half-ring waveguide, and the second transmission waveguide connection forms a second transmission zone between the second half-ring waveguide and the first half-ring waveguide. 16. The method according to claim 15, wherein the determining the length parameter of the ring waveguide according to the target frequency component comprises: Obtaining the dispersion frequency shift range of the signal converter, wherein the signal converter is used to convert the charge tunneling event in the quantum dot device into the dispersion frequency shift of the signal; According to the material property of the microring resonator, the target frequency component is selected from the dispersion frequency shift range as the resonant frequency of the microring resonator, wherein the microring resonator having the resonant frequency FWHM is less than the bandwidth of the signal converter; calculating a waveguide length of the ring waveguide according to the target frequency component; Determine the radius of the semi-ring waveguide, the radius of the ring segment, the length of the straight line segment and the number of meandering cycles as the length parameter according to the length of the waveguide and the deployment information of the microring resonator; Wherein, both the first transmission waveguide and the second transmission waveguide are meander-shaped waveguides, the first transmission waveguide includes a first number of first meandering periods connected in sequence, and the second transmission waveguide includes A second number of second meandering periods connected in sequence, the first number being the same as or different from the second number, the first meandering period comprising sequentially connected first partial ring segments, first straight line segments, second A half ring segment, a second straight line segment and a second partial ring segment, the second meandering period includes a third partial ring segment, a third straight line segment, a second half ring segment, a fourth straight line segment and a second half ring segment connected in sequence. four-part ring segment; Wherein, the radius of the half-ring waveguide is the radius of the first half-ring waveguide and the second half-ring waveguide, and the ring segment radius is the first partial ring segment, the second partial ring segment, and the third ring segment. The partial annular segment, the fourth partial annular segment, the radius of the first semi-annular segment and the second semi-annular segment, the length of the straight line segment is the first straight line segment, the second straight line segment, The lengths of the third straight line segment and the fourth straight line segment and the number of meandering cycles are the sum of the first number and the second number. 17. A measuring device for a state of a qubit, comprising: The input module is used to convert the initial frequency sweep signal into an initial resonance signal and input it to the quantum dot device to be measured; An acquisition module, configured to acquire the target resonance signal returned by the quantum dot device; a separation module, configured to separate a target signal of a target frequency component from the target resonance signal, wherein the target frequency component is a frequency associated with a charge tunneling event in the quantum dot device; A detection module, configured to detect the dispersion frequency shift of the target signal, wherein the dispersion frequency shift of the separated signal indicates that the charge tunneling event has occurred in the quantum dot device, and the charge tunneling event For characterizing the silicon-based spin qubit state in the quantum dot device; Wherein, the separation module is configured to: separate the target signal of the target frequency component from the target resonance signal through a microring resonator, wherein the microring resonator includes: a first straight waveguide, A second straight waveguide and a ring waveguide, the first straight waveguide is connected to the second straight waveguide through the ring waveguide, the input port of the first straight waveguide is used to input the target resonance signal, the second straight waveguide The output port of the straight waveguide is used to output the target signal satisfying the resonance condition of the microring resonator, and the resonance condition is the target frequency component. 18. A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, wherein when the computer program is executed by a processor, any one of claims 12 to 16 is implemented. The steps of the method. 19. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and operable on the processor, characterized in that the rights are realized when the processor executes the computer program The steps of the method described in any one of claims 12 to 16.

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