CN115545205B - Determination method and determination device for multi-quantum bit measurement result and quantum computer - Google Patents
Determination method and determination device for multi-quantum bit measurement result and quantum computer Download PDFInfo
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Abstract
The invention provides a method, a device and a quantum computer for determining a multi-quantum bit measurement result, wherein when the multi-quantum bit measurement result is determined, a quantum bit reading feedback signal for N related quantum bits is firstly obtained, then a quantum state measurement value of each quantum bit is obtained according to the quantum bit reading feedback signal, and finally the N related quantum bit measurement results are determined according to the information weight of each quantum bit and the quantum state measurement value of each quantum bit, so that the determination of the measurement results of the plurality of related quantum bits is realized, the plurality of related quantum bits can be applied, the practicability of the plurality of related quantum bits is improved, and the application scene of the plurality of related quantum bits is enlarged.
Description
Technical Field
The invention belongs to the technical field of quantum measurement and control, and particularly relates to a method and a device for determining a multi-quantum bit measurement result and a quantum computer.
Background
The qubit information is a quantum state of the qubit, the basic quantum states are a |0> state and a |1> state, the quantum state of the qubit changes after the qubit is operated, and on the quchip, the execution result is reflected that the quantum state of the qubit changes after the execution of the quchip, that is, the execution result of the quchip, and the execution result is carried by a qubit reading signal (generally, an analog signal) and transmitted.
The process of rapidly measuring the quantum state of the quantum bit by the quantum bit reading signal is a key work for knowing the execution performance of the quantum chip, and the high accuracy of the quantum bit measurement result is always an important index for the continuous pursuit of the quantum computing industry. The prior art is mature in determining the measurement result of a single quantum bit which is not influenced by other quantum bits, but a plurality of related quantum bits have more practical and wide application prospects. Illustratively, two associated qubits running a double quantum logic gate or a plurality of associated qubits running a multiple quantum logic gate; further exemplary, a plurality of associated qubits of the quantum computing task are run. In these examples, determination of the measurement results of the plurality of associated qubits is particularly important. To date, there is no technology related to a method of determining the measurement results of a plurality of associated qubits. Therefore, how to measure a plurality of associated qubits and ensure accuracy of measurement results is a problem that needs to be solved at present.
Disclosure of Invention
The invention aims to provide a method and a device for determining a multi-quantum bit measurement result and a quantum computer, which are used for solving the problem that measurement results of a plurality of related quanta cannot be accurately determined in the prior art, so that a plurality of related quanta can be applied.
To achieve the above object, in a first aspect, the present invention provides a method for determining a multiple-quantum bit measurement result, including:
acquiring a quantum bit reading feedback signal aiming at N associated quantum bits, wherein N is an integer greater than or equal to 2;
reading a feedback signal according to the quantum bit to obtain a quantum state measured value of each quantum bit;
and determining the measurement results of N associated quantum bits according to the information weight of each quantum bit and the quantum state measurement value of each quantum bit.
Optionally, before obtaining the quantum state measurement value of each of the qubits according to the qubit reading feedback signal, the method further includes:
establishing first quantum state criteria about N associated quantum bits, wherein the first quantum state criteria are used for acquiring quantum state measurement values of each quantum bit according to the quantum bit reading feedback signals.
Optionally, establishing the first quantum state criterion for the N associated qubits comprises:
acquiring first joint read signals when N associated quantum bits are simultaneously in a first quantum state;
acquiring second joint read signals when N associated quantum bits are simultaneously in a second quantum state;
acquiring coordinate point data of each quantum bit in an IQ coordinate system based on the first combined reading signal and the second combined reading signal;
determining a second quantum state criterion corresponding to each quantum bit according to the coordinate point data, wherein the second quantum state criterion is used for distinguishing the first quantum state from the second quantum state;
and associating second quantum state criteria corresponding to the quantum bits to obtain the first quantum state criteria.
Optionally, establishing a first quantum state criterion for the N associated qubits includes:
sequentially determining one of N associated qubits as a target qubit;
acquiring a first combined reading signal when the target quantum bit and other quantum bits are simultaneously in a first quantum state;
acquiring a second combined reading signal when the target quantum bit is in a second quantum state and the rest quantum bits are in a first quantum state, wherein the first quantum state is a |0> state, and the second quantum state is a |1> state;
acquiring coordinate point data of a target quantum bit in an IQ coordinate system based on the first combined reading signal and the second combined reading signal;
determining a second quantum state criterion corresponding to the target quantum bit according to the coordinate point data, wherein the second quantum state criterion is used for distinguishing the first quantum state from the second quantum state;
and associating each quantum bit as a second quantum state criterion corresponding to the target quantum bit to obtain the first quantum state criterion.
Optionally, the second quantum state criterion is one of a linear equation or a curvilinear equation.
Optionally, determining the second quantum state criterion according to the coordinate point data includes:
acquiring a distribution graph of the coordinate point data in an IQ coordinate system; the distribution pattern comprises a first pattern corresponding to the quantum bit in the first quantum state and a second pattern corresponding to the quantum bit in the second quantum state;
acquiring the central positions of the first graph and the second graph;
and determining the perpendicular bisectors of the connecting lines of the two central positions as a second quantum state criterion.
Optionally, obtaining the quantum state measurement value of each of the quantum bits according to the quantum bit reading feedback signal includes:
determining sub-signals corresponding to each quantum bit in the quantum bit reading feedback signal according to the frequency of the reading signal required by each quantum bit;
processing each sub-signal to obtain corresponding coordinate point data, wherein the coordinate point data are data of an IQ coordinate system;
and determining quantum state measured values of all the quantum bits according to the first quantum state criterion and all the coordinate point data.
Optionally, determining the measurement results of the N associated qubits according to the information weight of each qubit and the quantum state measurement value of each qubit includes:
determining characteristic values of measurement results of N associated quantum bits according to the information weight of each quantum bit and the quantum state measurement value of each quantum bit;
and determining N associated qubit measurement results according to the occurrence frequency of the characteristic value of the measurement result in multiple measurements.
In a second aspect, the present invention provides a multi-quantum bit measurement determining apparatus, including:
the first acquisition module is used for acquiring a quantum bit reading feedback signal aiming at N correlated quantum bits, wherein N is an integer greater than or equal to 2;
the second acquisition module is used for acquiring quantum state measured values of all the quantum bits according to the quantum bit reading feedback signals;
and the determining module is used for determining the measuring results of N associated quantum bits according to the information weight of each quantum bit and the quantum state measuring value of each quantum bit.
In a third aspect, the present invention provides a quantum computer for performing quantum computation using the method for determining a multiple quantum bit measurement result as described in the first aspect, or comprising the apparatus for determining a multiple quantum bit measurement result as described in the second aspect.
Compared with the prior art, the method and the device for determining the multi-quantum bit measurement result and the quantum computer provided by the invention have the following beneficial effects: when determining the measurement results of multiple quantum bits, firstly acquiring quantum bit reading feedback signals for N associated quantum bits, then acquiring quantum state measurement values of all the quantum bits according to the quantum bit reading feedback signals, and finally determining the measurement results of the N associated quantum bits according to the information weight of all the quantum bits and the quantum state measurement values of all the quantum bits, thereby determining the measurement results of the multiple associated quantum bits, enabling the multiple associated quantum bits to be applied, improving the practicability of the multiple associated quantum bits and expanding the application scenes of the multiple associated quantum bits.
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In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of a hardware structure of a computer terminal according to a method for determining a multiple quantum bit measurement result according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a superconducting quantum chip according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for determining a multiple quantum bit measurement result according to an embodiment of the present invention;
FIG. 4 is a flow chart of a method for establishing a first quantum state criterion for N associated qubits according to an embodiment of the present invention;
FIG. 5 is a flow chart of yet another method for establishing a first quantum state criterion for N associated qubits provided by an embodiment of the present invention;
FIG. 6 is a flow chart of a method for determining the second quantum state criterion based on the coordinate point data according to an embodiment of the present invention;
FIG. 7 is a distribution diagram of an IQ coordinate system according to an embodiment of the present invention;
FIG. 8 is a flow chart of a method for obtaining quantum state measurements of each of the qubits according to the qubit read feedback signal according to an embodiment of the present invention;
FIG. 9 is a flow chart of a method for determining N associated quantum bit measurements based on information weights of each of the quantum bits and quantum state measurements of each of the quantum bits according to an embodiment of the present invention;
fig. 10 is a block diagram of a multi-quantum bit measurement determining apparatus according to an embodiment of the present invention.
Detailed Description
The method, the device and the quantum computer for determining the multi-quantum bit measurement result are further described in detail below with reference to the accompanying drawings and the specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
In the description of the present invention, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
The method provided in this embodiment may be executed in a computer terminal or similar computing device. Taking the example of running on a computer terminal, referring to fig. 1, the computer terminal may comprise one or more (only one is shown in fig. 1) processors 102 (the processor 102 may comprise, but is not limited to, a microprocessor MCU or a processing device such as a programmable logic device FPGA) and a memory 104 for storing data, and optionally the computer terminal may further comprise a transmission device 106 for communication functions and an input-output device 108. It will be appreciated by those skilled in the art that the configuration shown in fig. 1 is merely illustrative and is not intended to limit the configuration of the computer terminal described above. For example, the computer terminal may also include more or fewer components than shown in FIG. 1, or have a different configuration than shown in FIG. 1.
The memory 104 may be used to store software programs and modules of application software, such as program instructions/modules corresponding to a method for determining multiple quantum bit measurement results provided herein, and the processor 102 executes the software programs and modules stored in the memory 104 to perform various functional applications and data processing, i.e., implement the above-mentioned methods. Memory 104 may include high-speed random access memory, and may also include non-volatile solid-state memory. In some embodiments, the memory 104 may further include memory 104 remotely located relative to the processor 102, which may be connected to the computer terminal via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The transmission means 106 is arranged to receive or transmit data via a network. Specific examples of the network described above may include an unlimited network provided by a communication provider of the computer terminal. In one embodiment, the transmission means comprises a network adapter (Network Interface Controller, NIC) connectable to other network devices via the base station to communicate with the internet. In one embodiment, the transmission device 106 may be a Radio Frequency (RF) module, which is used to communicate with the internet wirelessly.
The method provided in this embodiment may be applied to the above-described computer terminal, or referred to as a quantum computer.
In a quantum computer, a quantum chip is a processor for performing quantum computation, referring to fig. 2, a plurality of quantum bits and reading resonant cavities are integrated on the quantum chip, the quantum bits and the reading resonant cavities are in one-to-one correspondence and are coupled with each other, a section of each reading resonant cavity, which is far away from the corresponding quantum bit, is connected to a reading signal transmission line integrally arranged on the quantum chip, and each quantum bit is coupled with an XY signal transmission line and a Z signal transmission line. The XY signal transmission line is used for receiving the quantum state regulation and control signal, the Z signal transmission line is used for receiving the magnetic flux regulation and control signal, the magnetic flux regulation and control signal comprises a bias voltage signal and/or a pulse bias regulation and control signal, the bias voltage signal and the pulse bias regulation and control signal can regulate and control the frequency of the quantum bit, and the reading signal transmission line is used for receiving the reading detection signal and transmitting the reading feedback signal.
The quantum bit regulation and treatment process is briefly described as follows:
and adjusting the frequency of the quantum bit to the working frequency by utilizing a magnetic flux adjusting and controlling signal on the Z signal transmission line, applying a quantum state adjusting and controlling signal to perform quantum state adjustment and control on the quantum bit in an initial state through the XY signal transmission line, and reading the quantum state of the quantum bit after adjustment and control by adopting a reading resonant cavity. Specifically, a carrier frequency pulse signal is applied through a read signal transmission line, which is generally called a read detection signal, the read detection signal is generally a microwave signal with the frequency of 4-8GHz, and the quantum state of the quantum bit is determined by analyzing a read feedback signal output by the read signal transmission line. The fundamental reason that the read resonator is capable of reading the quantum state of the qubit is that the different quantum states of the qubit have different dispersion frequency shifts to the read resonator, such that the different quantum states of the qubit have different responses to a read probe signal applied to the read resonator, which response signal is referred to as a read feedback signal. Only when the carrier frequency of the read probe signal of the qubit is very close to the natural frequency (also called resonant frequency) of the read resonant cavity, the read resonant cavity has a maximized distinguishable level due to the obvious difference of the response of the qubit to the read probe signal in different quantum states. Based on this, the quantum state in which the quantum bit is located is determined by analyzing the read feedback signal with a certain pulse length, for example, the read feedback signal collected each time is converted into one coordinate point of an orthogonal plane coordinate system (i.e., an I-Q plane coordinate system), and the corresponding quantum state is determined to be the |0> state or the |1> state according to the position of the coordinate point, which can be understood that the |0> state and the |1> state are two eigenstates of the quantum bit.
The invention provides a method, a device and a quantum computer for determining a multi-quantum bit measurement result, which are used for determining the measurement result of a plurality of associated quantum bits, so that the plurality of associated quantum bits can be applied, the practicability of the plurality of associated quantum bits is improved, and the application scene of the plurality of associated quantum bits is enlarged.
To this end, the present embodiment provides a method for determining a multiple-qubit measurement result, referring to fig. 3, the method includes the following steps:
step S1, acquiring a quantum bit reading feedback signal aiming at N related quantum bits, wherein N is an integer greater than or equal to 2.
In particular, the qubit read feedback signal is a signal obtained from a read signal transmission line that characterizes the measurement results for N associated qubits, and it should be noted that the qubit read feedback signal is an analog signal, the form of which includes, but is not limited to:those skilled in the art will appreciate that this form is a general representation of an analog signal and that the parameters in this representation are not described herein. Digital processing of the signal results in a corresponding complex signal containing quantum states, including but not limited to mixing and/or integrating the signal. In this embodiment, N is equal to 3, i.e. realThe determination of 3 qubit measurements now occurs, at which time the qubit read feedback signal contains quantum state information for 3 associated qubits.
And S2, reading a feedback signal according to the quantum bit to obtain a quantum state measured value of each quantum bit.
Specifically, the qubit reading feedback signal carries quantum state information of N associated qubits, and because frequencies of reading detection signals required by the respective qubits are different, different qubits have different responses to the reading detection signals applied to the corresponding reading cavities, so that the qubit reading feedback signal for the N associated qubits is more complex than information contained in the conventional single qubit reading feedback signal, and when quantum state information reading measurement is performed, quantum state measurement values of the N associated qubits are obtained by processing the qubit reading feedback signal.
And S3, determining the measurement results of N related quantum bits according to the information weight of each quantum bit and the quantum state measurement value of each quantum bit.
Specifically, the information weight of the qubit is set according to the bit of the qubit, and when the value of N is 3, a group of 3 qubits needs to be obtained at this time as the first bit.
For example, a first quantum state criterion may be established for N associated qubits before obtaining a quantum state measurement value for each of the qubits from the qubit read feedback signal, the first quantum state criterion being used to obtain a quantum state measurement value for each of the qubits from the qubit read feedback signal.
The inventors have found that the specific step of quantum state resolution of the qubit read feedback signal containing quantum state information can be achieved by establishing a first quantum state criterion. Specifically, by applying a carrier frequency pulse signal (read probe signal) to the qubit and measuring the qubit read feedback signal output by the read signal transmission line, corresponding quantum state information is obtained and recorded. By applying different carrier frequency pulse signals (reading detection signals) and repeating the process, measurement results are obtained which are characteristic of the respective qubit reading feedback signals, and the first quantum state criterion is generated based on the measurement results.
When the method is specifically applied, the collected quantum bit feedback signals are input into the first quantum state criterion, so that quantum state information corresponding to the quantum bit feedback signals can be obtained, a multi-quantum bit quantum state resolution process is realized, quantum computing steps are reduced, and quantum computing efficiency is improved.
As an example, referring to fig. 4, a first quantum state criterion is established for N associated qubits, comprising the steps of:
step S201, acquiring a first combined read signal when N associated qubits are simultaneously in a first quantum state, and a second combined read signal when N associated qubits are simultaneously in a second quantum state.
Specifically, when the inventor performs implementation, first quantum state control signals are applied to N associated quantum bits at the same time, so that each quantum bit is in a first quantum state, quantum state information of the quantum bit is read, and a corresponding first combined read signal is obtained; and similarly, applying second quantum state control signals to N associated quantum bits simultaneously, so that each quantum bit is in a second quantum state, and reading quantum state information of the quantum bit to obtain a corresponding second combined reading signal.
The first combined reading signal is a quantum bit reading feedback signal when N associated quantum bits are simultaneously in a first quantum state; the second combined read signal is a qubit read feedback signal when N associated qubits are simultaneously in a second quantum state.
Step S202, obtaining coordinate point data of each qubit in an IQ coordinate system based on the first joint read signal and the second joint read signal.
Specifically, IQ quadrature demodulation is performed on the first combined read signal to obtain two corresponding values I and Q, where the two values are corresponding in an IQ coordinate system, that is, coordinate point data of a set of IQ coordinate systems is formed.
And similarly, performing IQ orthogonal demodulation processing on the second combined read signal to obtain two corresponding values I and Q, wherein the two values are correspondingly arranged in an IQ coordinate system, namely coordinate point data of another group of IQ coordinate system is formed.
And step 203, determining a second quantum state criterion corresponding to each quantum bit according to the coordinate point data, wherein the second quantum state criterion is used for distinguishing the first quantum state from the second quantum state.
Specifically, after IQ quadrature demodulation processing is performed on the first combined read signal and the second combined read signal, corresponding coordinate point data can be obtained in an IQ coordinate system. Through a large number of repeated tests, a plurality of coordinate points in the IQ coordinate system can be obtained. The coordinate point data corresponding to the first combined read signal forms one area range value in the IQ coordinate system, and the coordinate point data corresponding to the second combined read signal forms the other area range value in the IQ coordinate system. Because the first quantum state and the second quantum state are different quantum states, a second quantum state criterion can be determined according to the region range value corresponding to the first combined read signal and the region range value corresponding to the second combined read signal, and the criterion is used for distinguishing the first quantum state from the second quantum state.
And step S204, associating each quantum bit as a second quantum state criterion corresponding to the target quantum bit, and obtaining the first quantum state criterion.
After determining the second quantum state criteria corresponding to each quantum bit according to the coordinate point data, the second quantum state criteria of the N associated quantum bits need to be associated to obtain the first quantum state criteria.
As yet another example, referring to fig. 5, a first quantum state criterion is established for N associated qubits, and another method is provided comprising the steps of:
step S211 sequentially determines one of the N associated qubits as a target qubit.
In a specific application, each time the method is executed, one of the N associated qubits is determined to be operated as a target qubit, and it is understood that N operations need to be executed to sequentially determine one of the N associated qubits as the target qubit. In addition, the order of the N qubits is not set in the order of the N qubits, but is generally set in the order of the N qubits according to the reading task.
Step S212, a first joint reading signal when the target quantum bit and other quantum bits are simultaneously in a first quantum state is obtained; and acquiring a second combined reading signal when the target quantum bit is in a second quantum state and the rest quantum bits are in a first quantum state, wherein the first quantum state is a |0> state, and the second quantum state is a |1> state.
Step S213, obtaining coordinate point data of the target qubit in the IQ coordinate system based on the first joint read signal and the second joint read signal.
Specifically, IQ quadrature demodulation is performed on the first combined read signal to obtain two corresponding values I and Q, where the two values are corresponding in an IQ coordinate system, that is, coordinate point data of a set of IQ coordinate systems is formed.
And similarly, performing IQ orthogonal demodulation processing on the second combined read signal to obtain two corresponding values I and Q, wherein the two values are correspondingly arranged in an IQ coordinate system, namely coordinate point data of another group of IQ coordinate system is formed.
Step S214, determining a second quantum state criterion corresponding to the target quantum bit according to the coordinate point data, where the second quantum state criterion is used to distinguish the first quantum state from the second quantum state.
Specifically, after IQ quadrature demodulation processing is performed on the first combined read signal and the second combined read signal, corresponding coordinate point data can be obtained in an IQ coordinate system. Through a large number of repeated tests, a plurality of coordinate points in the IQ coordinate system can be obtained. The coordinate point data corresponding to the first combined read signal forms one area range value in the IQ coordinate system, and the coordinate point data corresponding to the second combined read signal forms the other area range value in the IQ coordinate system. Because the first quantum state and the second quantum state are different quantum states, a second quantum state criterion can be determined according to the region range value corresponding to the first combined read signal and the region range value corresponding to the second combined read signal, and the criterion is used for distinguishing the first quantum state and the second quantum state.
And step S215, associating each quantum bit as a second quantum state criterion corresponding to the target quantum bit, and obtaining the first quantum state criterion.
After determining the second quantum state criteria corresponding to each quantum bit according to the coordinate point data, the second quantum state criteria of the N associated quantum bits need to be associated to obtain the first quantum state criteria.
It should be noted that, the difference between the two methods for establishing the first quantum state criteria about the N associated quantum bits provided in this embodiment is that when the quantum state information reading measurement is performed on the N associated quantum bits, in the first measurement method, the target quantum bit is identical to the quantum states of other quantum bits, that is, the target quantum bit is identical to the first quantum state and the second quantum state; in the second measurement method, the quantum states of the target qubit are respectively set in a first quantum state and a second quantum state, and the quantum states of other qubits are always in the first quantum state, wherein the first quantum state is a |0> state, and the second quantum state is a |1>. When N associated qubits are read in quantum states at the same time, read crosstalk occurs between them, but researchers have found that these 2 approaches are all feasible with substantially identical results without or very little read crosstalk.
The second quantum state criterion is, for example, one of a linear equation or a curvilinear equation. When the method is applied specifically, the quantum bit reading feedback signal when the quantum bit is in an unknown quantum state is converted into coordinate point data of an IQ coordinate system. As described above, when the N associated qubits are in different quantum states, the area range values of the coordinate point data of the corresponding IQ coordinate system are visually displayed. And setting a proper equation based on different regional range values, namely effectively distinguishing the regional range corresponding to the coordinate point data in the IQ coordinate system, and obtaining the corresponding quantum state. The coordinate point data is directly compared with the function value of the second quantum state criterion, so that whether the unknown quantum state is the first quantum state or the second quantum state can be judged, the reading process of the quantum bit quantum state is greatly simplified, and the operation speed of a quantum computing system comprising a quantum chip and a quantum chip measurement and control system is ensured.
For example, referring to fig. 6, determining the second quantum state criterion according to the coordinate point data includes the following steps:
step S2031: acquiring a distribution graph of the coordinate point data in an IQ coordinate system; the distribution pattern includes a first pattern corresponding to the qubit in the first quantum state and a second pattern corresponding to the qubit in the second quantum state.
Referring to fig. 7, the process of obtaining the distribution pattern may be: the method comprises the steps of repeating acquisition measurement for a certain number of times and analysis reading for a read feedback signal by using high-sampling-rate signal acquisition equipment, for example, repeating 5000 acquisition measurements, acquiring the read feedback signal with a certain pulse length when each acquisition measurement is performed, and analyzing and converting the read feedback signal into coordinate point data of an orthogonal plane coordinate system (namely an I-Q plane coordinate system), wherein 5000 samples correspond to 5000 coordinate point data in the orthogonal plane coordinate system, and a first graph and a second graph of a graph IQ coordinate system are formed by 5000 points.
Step S2032, obtaining a center position of the first graph and the second graph distribution.
And step 2033, determining the perpendicular bisectors of the connecting lines of the two central positions as second quantum state criteria.
Specifically, after the first graph and the second graph of the IQ coordinate system are obtained, the inventor designs a method for effectively distinguishing the first graph and the second graph, namely, determining the perpendicular bisector of the connecting line of the central positions of the first graph and the second graph as the second quantum state criterion, so that the first graph and the second graph are symmetrical relative to the second quantum state criterion, and coordinate point data in the first graph and the second graph can be distinguished more conveniently, namely, quantum states of quantum bits can be distinguished simply and efficiently.
For example, referring to fig. 8, the method for obtaining the quantum state measurement value of each of the qubits according to the qubit reading feedback signal includes the following steps:
step S21, determining the sub-signals corresponding to the quantum bits in the quantum bit reading feedback signal according to the frequency of the reading signal required by the quantum bits.
It should be noted that, the working frequency of each qubit on the quantum chip is different, and the working frequency of the reading resonant cavity coupled with the qubit is also different, where the frequency of the reading detection signal required by each qubit needs to correspond to the frequency of the qubit to be read and the frequency of the reading resonator, that is, the frequency of the reading detection signal required by each qubit is also different.
Correspondingly, the obtained qubit read feedback signal is also a mixed signal comprising a plurality of qubit frequencies, wherein the mixed information comprises the frequencies of the read signals, and sub-signals corresponding to the qubits respectively can be obtained from the mixed information of the qubit read feedback signal. When the multi-quantum state is read, the sub signals corresponding to the quantum bits are determined first to ensure the accuracy of the multi-quantum state reading.
Step S22, processing each sub-signal to obtain corresponding coordinate point data, where the coordinate point data is data of an IQ coordinate system.
Specifically, the sub-signal of each qubit obtained by the qubit reading feedback signal is an analog signal carrying the quantum state information of the qubit, and the quantum state information needs to be read from the analog signal. Specifically, IQ quadrature demodulation is performed on the sub-signals to obtain two corresponding values I and Q, where the two values are corresponding in an IQ coordinate system.
And S23, determining quantum state measured values of the quantum bits according to the first quantum state criterion and the coordinate point data.
Specifically, after coordinate point data in the corresponding IQ coordinate system is obtained by reading the feedback signal through the quantum bit, quantum state information corresponding to the feedback signal, namely quantum state measurement values of each quantum bit, can be obtained efficiently based on the first quantum state criterion set up in the IQ coordinate system.
For example, referring to fig. 9, determining the measurement results of N associated qubits according to the information weight of each of the qubits and the quantum state measurement value of each of the qubits includes the steps of:
and S31, determining characteristic values of measurement results of N associated quantum bits according to the information weight of each quantum bit and the quantum state measurement value of each quantum bit.
And step S32, determining N associated qubit measurement results according to the occurrence frequency of the characteristic value of the measurement result in multiple measurements.
When the information weight of the qubit is set according to the bit position of the qubit, and the value of N is 3, a group of 3 qubits need to be obtained at this time and used as the first bit. To reduce the occupation of computational resources, 3 first qubits q3q2q1 are preferred. It is to be understood that the number of eigenvalues of q3q2q1 is 8 in total, and the sum of squares of the amplitudes of the eigenvalues is 1 from |000> to |111>, and the specific distribution is not limited.
And obtaining a plurality of corresponding measurement results by carrying out multiple measurements on N associated quantum bits, counting the occurrence probability of the characteristic values of the measurement results in multiple measurements, and determining the accuracy degree of the measurement results by comparing the probability of the characteristic values of the measurement results.
Based on the same inventive concept, the present embodiment provides a determination device of a multiple quantum bit measurement result, referring to fig. 10, the determination device includes:
a first obtaining module 510, configured to obtain a qubit read feedback signal for N associated qubits, where N is an integer greater than or equal to 2;
a second obtaining module 520, configured to obtain a quantum state measurement value of each of the qubits according to the qubit reading feedback signal;
a determining module 530 is configured to determine measurement results of N associated qubits according to the information weight of each qubit and the quantum state measurement value of each qubit.
In addition, based on the same inventive concept, the present embodiment provides a quantum computer that performs quantum computation using the determination method of the multiple quantum bit measurement result as described above, or includes the determination device of the multiple quantum bit measurement result as described above.
In addition, based on the same inventive concept, the present embodiment provides a quantum computer that performs quantum computation using the determination method of the multiple quantum bit measurement result as described above, or includes the determination device of the multiple quantum bit measurement result as described above.
In summary, the method, the device and the quantum computer for determining the multiple quantum bit measurement result provided by the invention have the following advantages: when determining the measurement results of multiple quantum bits, firstly acquiring quantum bit reading feedback signals for N associated quantum bits, then acquiring quantum state measurement values of all the quantum bits according to the quantum bit reading feedback signals, and finally determining the measurement results of the N associated quantum bits according to the information weight of all the quantum bits and the quantum state measurement values of all the quantum bits, thereby determining the measurement results of the multiple associated quantum bits, enabling the multiple associated quantum bits to be applied, improving the practicability of the multiple associated quantum bits and expanding the application scenes of the multiple associated quantum bits.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.
Claims (9)
1. A method for determining a multiple-qubit measurement, comprising:
acquiring a quantum bit reading feedback signal aiming at N associated quantum bits, wherein N is an integer greater than or equal to 2;
reading a feedback signal according to the quantum bit to obtain a quantum state measured value of each quantum bit;
determining characteristic values of measurement results of N associated quantum bits according to the information weight of each quantum bit and the quantum state measurement value of each quantum bit; and determining N associated qubit measurement results according to the occurrence frequency of the characteristic value of the measurement result in multiple measurements.
2. A method of determining a multiple quantum bit measurement as claimed in claim 1, further comprising, prior to obtaining a quantum state measurement for each of the quantum bits from the quantum bit read feedback signal:
establishing first quantum state criteria about N associated quantum bits, wherein the first quantum state criteria are used for acquiring quantum state measurement values of each quantum bit according to the quantum bit reading feedback signals.
3. A method of determining a multiple quantum bit measurement according to claim 2, wherein establishing a first quantum state criterion for the N associated quantum bits comprises:
acquiring first joint read signals when N associated quantum bits are simultaneously in a first quantum state;
acquiring second joint read signals when N associated quantum bits are simultaneously in a second quantum state;
acquiring coordinate point data of each quantum bit in an IQ coordinate system based on the first combined reading signal and the second combined reading signal;
determining a second quantum state criterion corresponding to each quantum bit according to the coordinate point data, wherein the second quantum state criterion is used for distinguishing the first quantum state from the second quantum state;
and associating second quantum state criteria corresponding to the quantum bits to obtain the first quantum state criteria.
4. A method of determining a multiple quantum bit measurement according to claim 2, wherein establishing a first quantum state criterion for the N associated quantum bits comprises:
sequentially determining one of N associated qubits as a target qubit;
acquiring a first combined reading signal when the target quantum bit and other quantum bits are simultaneously in a first quantum state;
acquiring a second combined reading signal when the target quantum bit is in a second quantum state and the rest quantum bits are in a first quantum state, wherein the first quantum state is a |0> state, and the second quantum state is a |1> state;
acquiring coordinate point data of a target quantum bit in an IQ coordinate system based on the first combined reading signal and the second combined reading signal;
determining a second quantum state criterion corresponding to the target quantum bit according to the coordinate point data, wherein the second quantum state criterion is used for distinguishing the first quantum state from the second quantum state;
and associating each quantum bit as a second quantum state criterion corresponding to the target quantum bit to obtain the first quantum state criterion.
5. A method of determining a multiple quantum bit measurement according to claim 3 or 4 wherein the second quantum state criterion is one of a linear equation or a curvilinear equation.
6. A method of determining a multiple quantum bit measurement according to claim 3 or 4, wherein determining the second quantum state criterion from the coordinate point data comprises:
acquiring a distribution graph of the coordinate point data in an IQ coordinate system; the distribution pattern comprises a first pattern corresponding to the quantum bit in the first quantum state and a second pattern corresponding to the quantum bit in the second quantum state;
acquiring the central positions of the first graph and the second graph;
and determining the perpendicular bisectors of the connecting lines of the two central positions as a second quantum state criterion.
7. A method of determining a multiple quantum bit measurement as claimed in claim 2 wherein obtaining a quantum state measurement for each of the quantum bits from the quantum bit read feedback signal comprises:
determining sub-signals corresponding to each quantum bit in the quantum bit reading feedback signal according to the frequency of the reading signal required by each quantum bit;
processing each sub-signal to obtain corresponding coordinate point data, wherein the coordinate point data are data of an IQ coordinate system;
and determining quantum state measured values of all the quantum bits according to the first quantum state criterion and all the coordinate point data.
8. A multiple-qubit measurement determining apparatus, comprising:
the first acquisition module is used for acquiring a quantum bit reading feedback signal aiming at N correlated quantum bits, wherein N is an integer greater than or equal to 2;
the second acquisition module is used for acquiring quantum state measured values of all the quantum bits according to the quantum bit reading feedback signals;
the determining module is used for determining the characteristic values of the measuring results of N associated quantum bits according to the information weight of each quantum bit and the quantum state measuring value of each quantum bit; and determining N associated qubit measurement results according to the occurrence frequency of the characteristic value of the measurement result in multiple measurements.
9. A quantum computer characterized in that quantum computation is performed using the method for determining a multiple quantum bit measurement result according to any one of claims 1 to 7, or comprising the device for determining a multiple quantum bit measurement result according to claim 8.
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