WO2023143457A1 - Method and apparatus for determining high-energy-state regulation and control signal of quantum bit, and quantum computer - Google Patents

Abstract

Provided in the embodiments of the present description are a method and apparatus for determining a high-energy-state regulation and control signal of a quantum bit, and a quantum computer. The method comprises: adjusting a wave parameter of a second regulation and control signal within a preset wave parameter scanning range, and respectively applying a first regulation and control signal and the adjusted second regulation and control signal to a target quantum bit in sequence, such that the target quantum bit transitions from a first excited state to a second excited state, wherein the first regulation and control signal is used for regulating and controlling the reversal of the target quantum bit between the first excited state and a ground state; and acquiring the wave parameter of the second regulation and control signal, which is used for making the target quantum bit transition from the first excited state to the second excited state, and taking same as a wave parameter of a high-energy-state regulation and control signal. On the basis of a high-energy-state regulation and control signal of a quantum bit, which is determined by the method provided in the embodiments of the present description, the quantum state of the quantum bit can be accurately regulated and controlled to a high-energy-level excited state, thereby providing a basis for realizing high-energy-state regulation and control of the quantum bit and improving the reading fidelity of the quantum bit.

Description

Method and device for determining qubit high-energy state control signal and quantum computer technical field

The embodiments of this specification relate to the technical field of quantum computing, and in particular to a method and device for determining a qubit high-energy state control signal, and a quantum computer.

Background technique

Since quantum computing has the potential to far exceed the performance of classical computers in solving specific problems, in order to realize quantum computers, it is necessary to obtain a quantum chip containing a sufficient number and quality of qubits, and to be able to perform extremely high fidelity on qubits. Quantum logic gate operation and reading.

Qubits are carriers of information processing in quantum computing, and related technologies use artificial multi-level systems to realize qubits. Common artificial multi-level systems include superconducting Josephson junctions, semiconductor quantum dots, ion traps, etc. In related technologies, the lowest energy level and the second lowest energy level of the artificial multi-energy level system are respectively used as the ground state and the first excited state of the qubit (ie |0> state and |1> state). Since the energy level difference between two adjacent energy levels in this multi-energy level system is not equal, the ground state and the first excited state of the qubit can be isolated from other high excited states to form a {|0>, |1 >} subspace. However, in actual bit manipulation, such as the common CZ double-bit gate operation, the qubit may be excited from the first excited state to a higher-level high-energy state, such as the second excited state (|2> state). This high-level leakage reduces the manipulation precision of quantum logic gates and the readout fidelity of qubits, thereby affecting the precision of quantum computing.

In order to better use quantum chips for quantum computing, reduce and optimize the above-mentioned high-energy state leakage errors, it is necessary to realize the high-energy state regulation and reading of qubits.

Based on this, it is urgent to provide a method for determining the high-energy state control signal of the qubit to determine the high-energy state control signal of the qubit more accurately, so as to realize the high-energy state control of the qubit.

It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the embodiments of the present specification, and therefore may include information that does not constitute prior art known to those of ordinary skill in the art.

Contents of the invention

The embodiments of this specification provide a method, device and quantum computer for determining a qubit high-energy state control signal, which are used to improve the accuracy of the wave parameters of the high-energy state control signal for qubit high-energy state control.

One embodiment of the description provides a method for determining a qubit high-energy state control signal, the determination method includes: adjusting the wave parameters of the second control signal within the preset wave parameter scanning range, and sequentially sending the target The qubit applies the first control signal and the adjusted second control signal to make the target qubit transition from the first excited state to the second excited state; wherein the first control signal is used to control the target quantum The bit is flipped between the first excited state and the ground state; obtaining the wave parameter of the second control signal that makes the target qubit transition from the first excited state to the second excited state, as the wave parameter of the high-energy state control signal parameter.

In another embodiment of the present specification, the wave parameter is amplitude; the wave parameter of the second control signal is adjusted within the preset wave parameter scanning range, and the first control signal is respectively applied to the target qubits in sequence and the adjusted second control signal, to make the target qubit transition from the first excited state to the second excited state, comprising: adjusting the amplitude of the second control signal within a preset amplitude scanning range, and applying the first control signal, the second control signal and the first control signal to the target qubit sequentially after adjusting the amplitude of the second control signal each time to perform a Rabi oscillation experiment, Obtaining first signals corresponding to the target qubits respectively, wherein the first signals are measured signals containing final state information of the target qubits;

Obtaining the wave parameters of the second control signal that causes the target qubit to transition from the first excited state to the second excited state, as the wave parameters of the high-energy state control signal, includes: based on the amplitude of all the first signals For data or phase data, the amplitude of the second control signal corresponding to when the target qubit is in the second excited state is obtained as the amplitude of the high-energy state control signal.

In another embodiment of this specification, the acquiring the first signal corresponding to the target qubit includes:

Each of the first signals is obtained by reading a waveform signal; the frequency of the read waveform signal is set to the cavity frequency of a read resonant cavity coupled with the target qubit when the target qubit is in a ground state.

In another embodiment of the specification, after adjusting the amplitude of the second control signal each time, the first control signal, the second control signal and the first control signal are sequentially applied to the target qubit. Regulating signal In the Rabi oscillation experiment, the second regulating signal and the first regulating signal are output through the same signal output channel.

In another embodiment of the present specification, in the adjusting the amplitude of the second control signal within the preset amplitude scanning range, the amplitude scanning range is based on the amplitude of the first control signal It is determined that the amplitude of the second regulation signal is greater than the magnitude of the first regulation signal.

In another embodiment of the present specification, the adjusting the amplitude of the high-energy state regulation signal within the preset amplitude scanning range includes:

selecting an initial amplitude within the preset amplitude scanning range, and increasing or decreasing the initial amplitude based on a preset step size to obtain the adjusted amplitude;

Iteratively updating the adjustment amplitude based on the step size; wherein, the amplitude of the second regulation signal is equal to the adjustment amplitude.

In another embodiment of the present specification, the amplitude of the second control signal corresponding to the target qubit in the second excited state is acquired based on the amplitude data or phase data of all the first signals As the amplitude of the high-energy state control signal, the amplitude of the second control signal corresponding to the qubit in the second excited state is equal to the amplitude data or phase data of all the first signals The amplitude of the second control signal corresponding to the extremum.

In another embodiment of the present specification, the amplitude value of the second control signal corresponding to the target qubit in the second excited state is obtained based on the amplitude data or phase data of all the first signals, include:

fitting the amplitude data or the phase data to obtain amplitude fitting data or phase fitting data;

Identifying the extremum of the amplitude fitting data or phase fitting data, and obtaining the amplitude of the second regulation signal corresponding to the extremum as the second regulation corresponding to when the qubit is in the second excited state The amplitude of the signal.

In another embodiment of the specification, the determination method also includes:

The power and pulse width of the second regulation signal are determined based on the power and pulse width of the first regulation signal.

In another embodiment of the present specification, the determining the power and pulse width of the second control signal based on the power and pulse width of the first control signal includes:

The power and pulse width of the second control signal are the same as the power and pulse width of the first control signal.

In another embodiment of the specification, the determination method also includes:

The working frequency of the second regulating signal is determined based on the working frequency of the first regulating signal.

In another implementation manner of this specification, the operating frequency of the second regulation signal is obtained based on the frequency spectrum curve of the target qubit.

In another embodiment of the specification, the wave parameter is frequency; the wave parameter of the second control signal is adjusted within the preset wave parameter scanning range, and the first control signal and the adjusted wave parameter are respectively applied to the target qubit in sequence. The second regulation signal, to make the target qubit transition from the first excited state to the second excited state, including:

Applying a first control signal to the target qubit to control the target qubit to a first excited state;

Adjust the frequency of the second control signal within the preset frequency scanning range, and then apply the adjusted second control signal to the target qubit, wherein the second control signal can move the target qubit from transition from the first excited state to the second excited state;

Obtaining the wave parameters of the second control signal that causes the target qubit to transition from the first excited state to the second excited state, as the wave parameters of the high-energy state control signal, includes:

Obtain the spectrum curve of the target qubit;

The frequency of the second control signal corresponding to the extremum value of the frequency spectrum curve is the frequency of the high-energy state control signal for the target qubit to transition from the first excited state to the second excited state.

In another embodiment of the present specification, the frequency of the second control signal is adjusted within the preset frequency scanning range, and the adjusted second control signal is applied to the target qubit, the frequency scanning The range does not include the operating point frequency of the target qubit.

In another embodiment of the present specification, the frequency of the second control signal is adjusted within the preset frequency scanning range, and the adjusted second control signal is applied to the target qubit, the frequency scanning The range is set based on the operating point frequency and anharmonicity of the target qubit.

In another embodiment of the specification, the frequency scanning range is Wherein, f ₀₁ is the operating point frequency of the target qubit, and α is the anharmonicity of the target qubit.

In another embodiment of the present specification, the first control signal is applied to the target qubit, and the target qubit is controlled to the first excited state; the second control signal is adjusted within the preset frequency scanning range. Frequency, in the adjusted second control signal applied to the target qubit, the amplitude of the second control signal is larger than the amplitude of the first control signal, and the driving of the second control signal The power is the same as the driving power of the first control signal.

In another embodiment of the present specification, the first control signal is applied to the target qubit, and the target qubit is controlled to the first excited state; the second control signal is adjusted within the preset frequency scanning range. frequency, and applying the adjusted second control signal to the target qubit, the first control signal and the second control signal are output from the same signal channel of the quantum control system.

In another embodiment of the present specification, the first control signal is applied to the target qubit to control the target qubit into the first excited state, and the frequency of the first control signal is the same as that of the target qubit. Bits operate at the same frequency.

In another embodiment of the present specification, adjusting the frequency of the second control signal within the preset frequency scanning range, and then applying the adjusted second control signal to the target qubit includes:

The second control signal is generated by the second baseband waveform signal; the frequency variation range of the second baseband waveform signal is Wherein, IF is the frequency of the first baseband waveform signal used to generate the first regulation signal, and the first baseband waveform signal and the second baseband waveform signal are generated by a signal generator.

In another embodiment of this specification, after applying the second control signal to the target qubit, a third control signal is applied to the target qubit, wherein the third control signal The parameters are the same as those of the first control signal.

In another embodiment of the present specification, both the first control signal and the third control signal are π pulses capable of manipulating the target qubit to flip its quantum state between the ground state and the first excited state.

One embodiment of this specification provides a device for determining a qubit high-energy state control signal, the device for determining includes:

The control module is used to adjust the wave parameters of the second control signal within the preset wave parameter scanning range, and apply the first control signal and the adjusted second control signal to the target qubit in sequence, so as to make the target The qubit transitions from the first excited state to the second excited state; wherein the first control signal is used to control the target qubit to flip between the first excited state and the ground state;

A parameter acquisition module, configured to acquire the wave parameter of the second control signal that causes the target qubit to transition from the first excited state to the second excited state, as the wave parameter of the high-energy state control signal.

One embodiment of this specification provides a quantum computer, including the above-mentioned device for determining the high-energy state control signal of the qubit or using any of the methods described above to determine the high-energy state control signal of the qubit.

An embodiment of the present specification provides a computer storage medium, in which a computer program is stored, wherein the computer program is configured to execute the method described in any one of the above when running.

One embodiment of the present specification provides an electronic device, including a memory and a processor, the memory stores a computer program, and the processor is configured to run the computer program to perform any of the above-mentioned method.

Compared with the prior art, the implementation of this specification discloses a method for determining the qubit high-energy state control signal, by adjusting the wave parameters of the second control signal within the preset wave parameter scanning range, and sequentially sending the target The qubit applies the first control signal and the adjusted second control signal to make the target qubit transition from the first excited state to the second excited state; wherein the first control signal is used to control the target quantum The bit is flipped between the first excited state and the ground state; obtaining the wave parameter of the second control signal that makes the target qubit transition from the first excited state to the second excited state, as the wave parameter of the high-energy state control signal parameter. The qubit high-energy state control signal determined based on the method provided by the implementation of this specification can accurately control the quantum state of the qubit to the |2> state, in order to realize the high-energy state control of the qubit and improve the reading fidelity of the qubit degree provides the basis.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of this specification or related technologies, the following will briefly introduce the drawings that need to be used in the descriptions of the embodiments or the prior art. Obviously, the drawings in the following description are only Some implementations of this specification should therefore not be regarded as limiting the scope. For those skilled in the art, other drawings can also be obtained according to these drawings without creative work.

Figure 1 is a schematic diagram of the internal structure of a superconducting quantum chip using a superconducting Josephson junction system;

Fig. 2 is a schematic diagram of the energy level distribution of the multi-energy level structure system realizing the qubit in the related art;

FIG. 3 is a flow chart of a method for determining a qubit high-energy state control signal shown in an embodiment of this specification;

FIG. 4 is a flow chart of a method for determining a qubit high-energy state regulation signal shown in another embodiment of this specification;

Fig. 5 is a schematic diagram of quantum state regulation and reading circuits shown in another embodiment of the specification;

Fig. 6 is a flow chart of a method for determining a qubit high-energy state control signal shown in another embodiment of this specification;

FIG. 7 is a flow chart of a method for determining a qubit high-energy state control signal shown in another embodiment of this specification;

FIG. 8 is a flow chart of a method for determining a qubit high-energy state regulation signal shown in another embodiment of this specification;

FIG. 9 is a schematic diagram of the qubit excitation transition process shown in the embodiment of this specification;

Fig. 10 is a flow chart of a method for determining a qubit high-energy state regulation signal shown in another embodiment of this specification;

11 is a timing diagram of a measurement and control waveform signal for measuring the frequency of a high-energy state control signal of a qubit using the method provided by the embodiment of this specification;

FIG. 12 is a spectrum curve for measuring the frequency of a high-energy state control signal of a qubit using the method provided in the embodiment of this specification;

FIG. 13 is a structural block diagram of a device for determining a qubit high-energy state regulation signal shown in an embodiment of the present specification;

FIG. 14 is a structural block diagram of an electronic device shown in an embodiment of this specification.

Detailed ways

The qubit on the superconducting quantum chip is the carrier of the quantum state, carrying quantum information. Superconducting quantum computing has the advantage of running fast, been widely used by people. The regulation and reading of qubits on superconducting quantum chips is an important part of the physical realization of quantum computing. High-precision quantum state regulation and reading technology can improve the accuracy of quantum computing results.

See Figure 1. The qubit in the superconducting quantum chip adopting the superconducting Josephson junction system includes mutually coupled reading resonant cavity and qubit device. One end of the read resonant cavity away from the corresponding qubit device is connected to a read bus integrated on the superconducting quantum chip, and the read bus is used to receive qubit read signals and emit qubits Read feedback signal. Each qubit device of the superconducting quantum chip is connected with a bit regulation signal line (i.e. XY control line) and a magnetic flux modulation signal line (i.e. Z control line), wherein the bit regulation signal line is the quantum The bit provides a driving control signal for controlling the change of the quantum state of the qubit, and the magnetic flux modulation signal line provides the magnetic flux modulation signal for the qubit to control the change of the operating frequency of the qubit.

See Figure 2. At present, the qubits on the superconducting quantum chip are multi-level nonlinear harmonic oscillators, and their quantum states are mainly distinguished by the high and low energy levels. The qubit used in quantum computing in related technologies adopts a two-level structure composed of the ground state |0> and the first excited state |1> in a multi-level structure, forming a {|0>, |1>} subspace. At this time, the energy state of the qubit is only the ground state |0> and the first excited state |1>, so that the qubit only has {|0>, |1>} subspace quantum state information. However, due to the short relaxation time of the qubit from the first excited state |1> to the ground state |0>, this shortens the decoherence time of the qubit to a certain extent, making the reading fidelity of the quantum state low , making it difficult to obtain ideal quantum computing results in practical applications.

In addition, in the actual qubit quantum state control, such as the common CZ double-bit gate operation, the qubit may be excited to a higher energy state than the first excited state, that is, the second excited state |2>. This high-energy state leakage also reduces the readout fidelity of the qubits, which affects the accuracy of quantum computing results.

Therefore, based on the above analysis, the embodiments of this specification provide a method, device, and quantum computer for determining a qubit high-energy state control signal, which are used to determine a high-energy state control signal for qubit high-energy state control. It provides the basis for high-energy state regulation and improved readout fidelity of qubits.

In order to enable those skilled in the art to better understand the solution of the present application, the present application will be further described in detail below in conjunction with the drawings and specific implementation methods. Apparently, the described implementations are only some of the implementations of this application, not all of them. Based on the implementations in this specification, all other implementations obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present application.

Please refer to Figure 3. One embodiment of this specification provides a method for determining a high-energy state regulation signal of a qubit, the determination method comprising:

S101: Adjust the wave parameter of the second control signal within the preset wave parameter scanning range, and apply the first control signal and the adjusted second control signal to the target qubit in sequence, so that the target qubit is controlled by The first excited state transitions to the second excited state; wherein, the first control signal is used to control the target qubit to flip between the first excited state and the ground state.

It should be noted that the first control signal may be a π pulse, that is, a π-Pulse or Pauli-X gate, a Rabi driving signal capable of exciting the target qubit to the |1> state. Wherein, the first π pulse applied to the target qubit is used to drive the target qubit to be excited from the |0> state to the |1> state, and the second π pulse applied to the target qubit The π pulse is used to drive the target qubit back to the |0> state when the second control signal fails. The above-mentioned excited state is a concept corresponding to the ground state, and both the first excited state and a high-energy state with an energy level higher than the first excited state belong to the excited state. Two adjacent excited states can be two excited states with adjacent energy levels, such as the first excited state |1> and the second excited state |2>, the second excited state |2> and the third excited state |3 >, the third excited state |3> and the fourth excited state |4> and so on. Adjusting the state of the qubit to flip between two adjacent excited states means that the state of the qubit can be transitioned from the low excited state of the two adjacent excited states to the high excited state, and the state of the qubit can be Relaxation from a high excited state of two adjacent excited states to a low excited state.

The second control signal may be a signal for adjusting the state of the qubit to flip between the first excited state |1> and the second excited state |2>. The control signal of the qubit can be expressed by the following formula:

Among them, A(t) represents the magnitude of the qubit control signal, w represents the frequency of the qubit control signal, Represents the initial phase of the qubit control signal.

For the qubit on the superconducting quantum chip, the typical way to generate the control signal of the qubit is as follows: it is produced by an arbitrary waveform generator (Arbitrary Waveform Generator, AWG), a microwave local oscillator source and an IQ mixer.

In this embodiment, the wave parameters may include amplitude or frequency.

S102: Acquire wave parameters of a second control signal that causes the target qubit to transition from a first excited state to a second excited state, as wave parameters of the high-energy state control signal.

In this embodiment, different wave parameters correspond to different acquisition methods. When the wave parameter is amplitude, the amplitude of the high-energy state regulation signal can be obtained through the first signal obtained by the target qubit through a Rabi oscillation experiment. When the wave parameter is frequency, the frequency of the high-energy state regulation signal can be obtained through the spectrum curve of the target qubit.

The specific content of a method for determining a qubit high-energy state control signal provided in this application will be described in detail in the following embodiments.

See Figure 4. In one embodiment of this specification, when the wave parameter is amplitude, the method for determining the qubit high-energy state regulation signal may include:

S201: Adjust the amplitude of the second control signal within the preset amplitude scanning range, and apply the first control signal and the second control signal to the target qubit sequentially after adjusting the amplitude of the second control signal each time. The control signal and the first control signal are subjected to a Rabi oscillation experiment, and the first signal corresponding to the target qubit is respectively obtained, wherein the first signal is a measured signal containing final state information of the target qubit.

See Figure 5. In this embodiment, the first control signal (denoted as X01), the second control signal (denoted as X12) and the first control signal (denoted as X01) are sequentially applied to the target qubit for Rabi oscillation experiments, the The final state of the target qubit has two possibilities: one is that if the second control signal X12 with a specific amplitude can completely excite the target qubit in the |1> state to the |2> state (ie the second The control signal takes effect), then the final state of the target qubit is |2> state; the other is that if the high-energy state control signal X12 with a specific amplitude cannot make the target qubit in the |1> state completely excited to the |2> state (that is, the second control signal fails), then the final state of the target qubit is the |0> state. Therefore, there are two situations in the final state information of the target qubit contained in the first signal: one is that the first signal contains information that the target qubit is in the |2> state, and the other is that the target qubit is in the |2> state. The first signal contains the information that the target qubit is in the |0> state.

S202: Based on the amplitude data or phase data of all the first signals, obtain the amplitude of the second control signal corresponding to when the target qubit is in the second excited state as the amplitude of the high-energy state control signal .

Those skilled in the art may know that the parameters of the first signal include amplitude and phase, and one of the parameters may be selected to be obtained in practical applications.

The operation result of the superconducting quantum chip, that is, the calculation result of the quantum information processing process, is included in the quantum state of the qubit. Read (or measure) the quantum state of the qubits on it.

Dispersion reading technology is often used to read qubit quantum state information. Dispersion reading technology obtains the quantum state through state projection, without completely destroying the quantum state. Specifically, a read resonant cavity is nonlinearly coupled next to the qubit, and a read waveform signal is applied to the read resonant cavity, and the qubit quantum is obtained by rapidly exciting the photon number of the read resonant cavity through the read waveform signal. status information. The fundamental reason why the reading resonator can read the quantum state of the qubit is that different quantum states of the qubit produce different dispersion frequency shifts on the reading resonator, which makes the different quantum states of the qubit apply to the reading When the frequency of the read waveform signal on the resonator is very close to the cavity frequency (also called resonant frequency or natural frequency) of the read resonator, the read resonator will not affect the read waveform signal due to the qubits being in different quantum states. The response has a clear difference, that is, the qubit read waveform signal has the maximum distinguishability.

In some embodiments, each of the first signals is obtained by reading a waveform signal; the frequency of the read waveform signal is set to be coupled to the target qubit when the target qubit is in the ground state (|0> state) Read the cavity frequency of the resonator. In this way, all the final state information of the target qubit can be projected into the {|0>, |1>} subspace to read the quantum state, and the first signal can be obtained by reading the state of the qubit |1> .

In some implementation manners, the second regulation signal and the first regulation signal may be output by the same signal output channel of the IQ mixer. Therefore, the channel drive power is the same for both.

In some implementations, the amplitude scanning range may be determined based on the amplitude of the first control signal, and the amplitude of the second control signal may be greater than the amplitude of the first control signal. For example, if the amplitude of the first control signal is less than 0.5V, then the amplitude scanning range of the second control signal can be set to [0.5V, 1V].

In some implementations, the amplitude of the second regulation signal is equal to the adjustment amplitude. Adjusting the amplitude of the second regulation signal within the preset amplitude scanning range may include: selecting an initial amplitude within the preset amplitude scanning range, increasing or decreasing the The adjusted amplitude is obtained from the initial amplitude; and the adjusted amplitude is iteratively updated based on the step size. Specifically, for example, when the amplitude scanning range of the second control signal is [0.5V, 1V], a value in [0.5V, 1V] can be arbitrarily selected as the initial amplitude. For example, 0.6V can be selected as the initial amplitude. And the step size can also be set according to actual application requirements, and there is no limitation here. For example, the preset step size can be 0.01V, then the adjusted amplitude obtained by increasing or decreasing the step size based on the initial amplitude can be 0.61V or 0.59V. Then iteratively updates the adjustment amplitude based on the step size. For example, the second adjustment can use the adjustment amplitude acquired by the first adjustment as the initial amplitude, and then the adjustment amplitude obtained by increasing or decreasing the step size based on the initial amplitude can be 0.62V or 0.60V.

In some implementations, the amplitude of the second control signal corresponding to when the qubit is in the second excited state may be the amplitude corresponding to the extreme values of the amplitude data or phase data of all the first signals. Amplitude of the second control signal.

The amplitude data or phase data of each of the first signals has a one-to-one correspondence relationship with the amplitude of the second control signal, that is, the amplitude of the second control signal is adjusted to obtain a specific amplitude, based on the amplitude The second control signal of the value performs Rabi oscillation on the target qubit Experimentally, one corresponding amplitude data or phase data can be obtained. And when the second control signal with a certain amplitude can excite the target qubit from the |1> state to the |2> state, the corresponding amplitude or phase of the first signal will occur sudden change, so that the extremum of the amplitude data or phase data of the first signal appears. Therefore, the amplitude of the second control signal corresponding to when the target qubit is in the second excited state |2> can be obtained by calculating the extreme value of the amplitude data or phase data of the first signal. value. This amplitude is the target amplitude, which is the amplitude of the high-energy state control signal.

In addition, the amplitude data or the phase data is oscillation data, in order to further improve the accuracy of data extremum solution, the amplitude data or phase data of the first signal can be fitted, and based on the fitted The extreme value acquired by the amplitude fitting data or the phase fitting data is inversely deduced to obtain that the amplitude of the second control signal corresponding to the extreme value is the second control signal corresponding to when the qubit is in the second excited state the magnitude of .

In practical applications, a fitting function such as a sine function or a Fourier basis function may be used to perform fitting calculations on the amplitude data or the phase data, which is not limited here.

See Figure 6. The method for determining the qubit high-energy state control signal provided in another embodiment of this specification may also include:

S203: Determine the power and pulse width of the second regulation signal based on the power and pulse width of the first regulation signal.

It should be noted that the above S203 may be executed in parallel with the above S201 to S202, or may be executed after S202, which is not specifically limited in this embodiment.

In this embodiment, the second control signal and the first control signal can be output by the same signal output channel of the IQ mixer, and the drive power of the two channels is the same, so the power of the two is the same . In addition, for the convenience of experimental operation, the pulse width of the second control signal may be set to be the same as the pulse width of the first control signal.

See Figure 7. In one embodiment of this specification, when the wave parameter is amplitude, the method for determining the qubit high-energy state regulation signal may include:

S301: Adjust the amplitude of the second control signal within the preset amplitude scanning range, and apply the first control signal and the second control signal to the target qubit sequentially after adjusting the amplitude of the second control signal each time. The control signal and the first control signal are subjected to a Rabi oscillation experiment, and the first signal corresponding to the target qubit is respectively obtained, wherein the first signal is a measured signal containing final state information of the target qubit.

S302: Based on the amplitude data or phase data of all the first signals, obtain the amplitude of the second control signal corresponding to when the target qubit is in the second excited state as the amplitude of the high-energy state control signal .

S303: Determine the working frequency of the second regulating signal based on the working frequency of the first regulating signal.

Those skilled in the art can know that when the operating frequency of the second control signal is very close to the transition frequency of the target qubit from the |1> state to the |2> state, the target qubit can be Excited from the |1> state to the |2> state. Therefore, the operating frequency of the second control signal can be selected as the transition frequency of the target qubit from the |1> state to the |2> state.

In this embodiment, the transition frequency _f12 of the target qubit from the |1> state to the |2> state can pass the transition frequency of the |0> state to the |1> state by the target qubit (ie The operating frequency f ₀₁ of the first regulation signal is determined by the anharmonicity α of the target qubit, that is, f ₁₂ =f ₀₁ +α.

In this embodiment, the transition frequency f ₁₂ at which the target qubit transitions from the |1> state to the |2> state can also be obtained by performing an energy spectrum measurement experiment on the target qubit. Specifically, the energy spectrum measurement experiment is performed on the target qubit by applying a certain power and amplitude of the driving waveform signal to obtain the spectrum curve of the target qubit, and the two-photon excitation frequency is obtained from the spectrum curve Finally, the transition frequency f ₁₂ of the target qubit from the |1> state to the |2> state is calculated according _to the relationship f _{12 =f 02} −f ₀₁ .

In this implementation manner, the working frequency of the second regulation signal may also be obtained based on the frequency spectrum curve of the target qubit. Specifically, by applying a first control signal to the target qubit, control the target qubit to the |1> state, and then scan the frequency of a second control signal within a suitable frequency scanning range, and apply The second control signal with a certain frequency is used to further excite and transition the target qubit from the |1> state to the |2> state, and then read the quantum state of the target qubit and obtain the target quantum Bit spectrum curve. If the frequency of the second regulation signal can resonate with the transition frequency of the target qubit from the |1> state to the |2> state, there will be an Transition to the resonance peak corresponding to the |2> state, that is, the extreme value in the spectrum curve, and finally identify the frequency of the second control signal corresponding to the extreme value of the spectrum curve as the target qubit from The transition frequency from the |1> state to the |2> state.

S301 and S302 are basically the same as S201 and S202 in the above-mentioned implementation manner of this specification. For details, please refer to the above-mentioned implementation manner of this specification, and details are not repeated here.

It should be noted that the above S303 can be executed in parallel with the above S301 to S302, or it can be executed after S302. There is no specific limitation in the implementation manner of the specification.

In some implementation manners, the second control signal and the first control signal may use a flat-top Gaussian wave signal or a DRAG wave signal. The method for determining the qubit high-energy state control signal provided by the embodiment of this specification realizes the continuous excitation of the qubit by sequentially applying the π pulse and the second control signal, so that the qubit has a {|0>, |1>} subspace On the basis of the quantum state information, the {|1>, |2>} subspace quantum state information is excited by the high-energy state control signal. The qubit is subjected to Rabi oscillation experiments, and the second control signal of the qubit is traversed in the whole process. Amplitude, the first signal obtained by measuring the final state information of the qubit and the adopted π pulse determine the high-energy state regulation signal; when the second regulation signal completely excites the qubit to the |2> state, the corresponding second regulation The amplitude of the signal is the amplitude of the high energy state regulation signal. The qubit high-energy state control signal obtained based on the implementation method of this specification can accurately control the quantum state of the qubit to the |2> state, which provides a basis for realizing the high-energy state control of the qubit and improving the reading fidelity of the qubit base.

See Figure 8. In the implementation of this specification, when the wave parameter is frequency, the method for determining the qubit high-energy state control signal may include:

S401: Apply a first control signal to a target qubit, and control the target qubit to a |1> state.

See Figure 9. Manipulating the quantum state excitation transition of the qubit needs to be carried out energy level by level. The qubit must be excited to the |1> state before it can continue to be excited and transition to the |2> state.

In this embodiment, in order to control the target qubit to the |1> state, it is necessary to apply a control signal to the target qubit through a bit control signal line (XY control line). The regulation signal is the first regulation signal.

The specific values of the driving power, amplitude and width of the first control signal need to be determined according to different target qubits on different quantum chips, and are not limited here.

In some implementations, the first control signal is a π pulse (π-pulse) capable of manipulating the target qubit to flip its quantum state between the |0> state and the |1> state. The π pulse is the Pauli X-gate. At this time, the amplitude of the first control signal is within the range of 0V-1V, and the width can be set to 10ns-200ns.

S402: Adjust the frequency of the second control signal within the preset frequency scanning range, and then apply the adjusted second control signal to the target qubit, wherein the second control signal can convert the target qubit to A bit transitions from the |1> state to the |2> state.

Exemplarily, the frequency of the second control signal can be scanned within the preset frequency scanning range to obtain N (N is a positive integer greater than or equal to 2) frequency scanning points, and the target quantum in the |1> state The bit then applies the second regulation signal having the frequency of each of the frequency sweep points.

It should be noted that the above S401 needs to be repeatedly performed N times, where N is the number of frequency scanning points of the second control signal. In this way, it can be ensured that the quantum state of the target qubit is always in the |1> state before it is manipulated by the second control signal having the frequency of each of the frequency sweep points.

In order to further excite and transition the target qubit from the |1> state to the |2> state at a high energy level, it is necessary to apply a control signal to the target qubit again, and the driving power, amplitude, and The values of the width and the frequency need to be appropriate, so that the states of the target qubits can be excited and transitioned. In related technologies, the control of qubits is limited to the {|0>, |1>} subspace, so the control parameters that can control the qubits to the |2> state are basically unknown. Those skilled in the art can understand that, since the energy level of the |2> state of the qubit is higher than that of the |1> state, the amplitude of the control signal required for the excitation of the |2> state will be larger than that of the |1> state. The amplitude of the signal to be regulated should be large.

In this embodiment, the second control signal is continuously applied to the target qubit in the |1> state, in order to excite and transition the target qubit from the |1> state to the |2> state. In the implementation manner of this specification, for the convenience of implementation, the driving power, amplitude and width of the second regulation signal are all set to a fixed value based on experience.

In some embodiments, the amplitude of the second control signal is set to the maximum value of the amplitude of the control signal output by the quantum control system. Exemplarily, the amplitude of the second control signal may be 1V. The width of the second control signal may be set as a multiple of the width of the first control signal, such as 1 time, 1.5 times, 2 times, 2.5 times, etc., which is not limited here.

The frequency of the second control signal is adjusted within the preset frequency scanning range, in order to find the frequency of the high-energy state control signal that excites and transitions the target qubit from the |1> state to the |2> state .

In this embodiment, the frequency of the second control signal is adjusted within the preset frequency scanning range, that is, several frequency scans of the second control signal are obtained within the preset frequency scanning range point. Regarding the acquisition method of the frequency scanning points of the second control signal, in theory, the more frequency scanning points of the second control signal are selected, the denser the frequency scanning accuracy will be, but due to the large amount of data processing, Will reduce the test efficiency. Therefore, the acquisition method of the frequency scanning point of the second control signal can be set according to the comprehensive requirements of specific applications, and is not specifically limited here.

S403: Obtain the spectrum curve of the target qubit.

The measurement result of the energy level transition frequency of the qubit can be described as the spectrum curve of the qubit, where the ordinate of the spectrum curve is often expressed as the amplitude or phase of the qubit read feedback signal, and the abscissa is often expressed as the frequency of the qubit Ranges.

reading and measuring the quantum state of the target qubit after being regulated by the second control signal with a certain frequency sweep point, Acquiring magnitude or phase data of a qubit read feedback signal related to the target qubit. And using the frequency scanning range where the frequency scanning point of the second control signal is located and combining the amplitude or phase data of the qubit read feedback signal to draw the frequency spectrum curve of the target qubit.

S404: Obtain the frequency of the second control signal corresponding to the extremum of the frequency spectrum curve as the frequency of the high-energy state control signal for the target qubit to transition from the |1> state to the |2> state.

In this embodiment, the change in amplitude or phase of the second control signal pair at different frequencies and the qubit reading feedback signal of the target qubit can be reflected in the spectrum curve of the target qubit Influence. And when the frequency of the second control signal is the same as the transition frequency of the target qubit from the |1> state to the |2> state, a resonance peak will be generated on the spectrum curve of the target qubit. That is, when the frequency of the second control signal is the same as the transition frequency of the target qubit from the |1> state to the |2> state, the second control signal will excite the target qubit from the |1> The state transitions to the |2> state. At this time, the frequency of the read resonator is affected by the |2> state, and no longer resonates with the first control signal. At this time, the state of the read resonator will change drastically. The amplitude and phase of the bit read feedback signal will have a peak value or a valley value near the transition frequency of the target qubit from the |1> state to the |2> state. The peak or valley is the extremum of the spectrum curve, and whether the extremum is a peak or a valley depends on the design of the quantum circuit in practical applications.

Only when the frequency of the second control signal resonates with the actual value of the transition frequency _f12 of the target qubit from the |1> state to the |2> state, can the target qubit be excited from the |1> state to the |2> state. If the frequency scanning range covers the operating point frequency of the target qubit, that is, the frequency of the second regulation signal can be selected from the transition frequency of the target qubit excited transition from the |0> state to the |1> state f ₀₁ , at this time, the second control signal may control the target qubit to the |1> state instead of the |2> state, resulting in misjudgment of the measurement result. In order to reduce the generation of such misjudgment results, the frequency scanning range may not include the operating point frequency of the target qubit. Exemplarily, the frequency scanning range can take a value near the theoretical value of the transition frequency _f12 of the target qubit from the |1> state to the |2> state, that is, the frequency scanning range can be Wherein, f' ₁₂ is the theoretical value of the transition frequency f ₁₂ of the target qubit from the |1> state to the |2> state. α represents the anharmonicity of the qubit (α is a negative value).

Those skilled in the art can understand that, after the quantum chip is manufactured, the theoretical design value of the anharmonicity of each qubit on the quantum chip is basically determined. Therefore, the theoretical value of the transition frequency f ₁₂ for qubit excited transition from |1> state to |2> state is determined. However, due to the limitation of the quantum chip manufacturing process, there is a certain error between the actual value and the theoretical value, so the actual value needs to be obtained through measurement.

Since the transition frequency f ₁₂ of the target qubit from the | ₁ > state to the |2> state has the same theoretical value f'12 as the transition frequency f ₀₁ of the target qubit from the |0> state to the |1> state The relation f' ₁₂ =f ₀₁ +α. Wherein, therefore, the frequency adjustment range of the second control signal can be set based on the transition frequency f ₀₁ and anharmonicity of the target qubit transition from the |0> state to the |1> state. In this embodiment, the operating point frequency of the target qubit is the same as the transition frequency f ₀₁ of the excited transition from the |0> state to the |1> state. Therefore, the frequency scanning range can be set based on the operating point frequency and anharmonicity of the target qubit.

In some implementations, the frequency scanning range can be set as

In some embodiments, since the first control signal and the second control signal are signals that control the same target qubit, the driving power of the second control signal is the same as that of the first control signal. The driving power of the control signals may be the same.

In some embodiments, in order to simplify the hardware structure of the quantum control system for regulating the qubits of the quantum chip, the first control signal and the second control signal can be output from the same signal channel of the quantum control system. Therefore, the driving power of the first control signal and the second control signal output from the same signal channel must be the same.

In some implementations, the frequency of the first control signal is the same as the operating point frequency of the target qubit.

In some embodiments, the operating point frequency may be the maximum operating frequency point (i.e. Sweet Point) in the AC modulation spectrum curve of the target qubit. Those skilled in the art will understand that the target qubit operates at At this frequency point, it is not sensitive to the change of the magnetic flux modulation signal on the magnetic flux modulation signal line (Z control line), which is beneficial to improve the control accuracy of the quantum state of the target qubit.

It should be noted that the frequency of the control signal of the qubit is in the 4-6GHz high frequency band, and the quantum control system used for the control of the qubit includes a signal generator, a mixer for frequency conversion and a microwave local oscillator source, Wherein, the baseband waveform signal containing qubit control information is generated by the signal generator and input into the mixer and the microwave local oscillator signal generated by the microwave local oscillator source for up-conversion mixing to obtain the control signal of the qubit .

Setting the frequency of the baseband waveform signal is the baseband frequency WG of the qubit control signal, the frequency of the microwave local oscillator signal is the local oscillator frequency LO, the signal frequency of the intermediate frequency port of the mixer is IF, and the output port The signal frequency is RF, then according to the mixing principle, there is LO=RF-IF.

The local oscillator frequencies of the control signals output from the same signal channel can be the same. Therefore, if you want to splicing control signals with different frequencies and output them from the same signal channel, you need to adjust the frequency of the baseband waveform signal.

The frequency RF' of the final output signal of the mixer is determined by LO and WG, that is, RF'=LO+WG. Assuming that the baseband frequency WG corresponding to the transition frequency f ₀₁ of the first control signal applied to the target qubit is equal to IF, then LO=f ₀₁ −IF can be obtained. Then there is a baseband frequency WG'=f 12 -LO=f ₁₂ -f corresponding to the transition frequency f ₁₂ of the second control signal applied to the target qubit from the |1> state to the |2> _{state 01} +IF, and then according to the range of the transition frequency f ₁₂ from |1> state to |2> state It can be obtained that the variation range of the baseband frequency WG' is Wherein, IF is also the baseband frequency corresponding to the operating point frequency of the target qubit.

Therefore, in specific implementation, the frequency can be generated in the quantum control system as The baseband waveform signal, so that the output frequency is the second control signal, and apply the second control signal with a certain frequency to the target qubit in the |1> state. When the frequency of the second regulation signal can resonate with the transition frequency of the target qubit from the |1> state to the |2> state, the target qubit can be excited to transition from the |1> state to the |2> state.

The method for determining the qubit high-energy state control signal provided by the implementation of this specification is to control the target qubit to the |1> state by applying a first control signal to the target qubit, and then scan a qubit within the preset frequency scanning range. The frequency of the second regulation signal, and applying the second regulation signal with a certain frequency to the target qubit, so as to further excite and transition the target qubit to the |2> state, and then obtain the target qubit If the frequency of the second control signal can resonate with the transition frequency of the target qubit from the |1> state to the |2> state, there will be a frequency in the spectrum curve that is consistent with the target qubit from The |1> state transitions to the resonance peak corresponding to the |2> state, and finally identifies the extreme value in the spectrum curve, and obtains the frequency of the second control signal corresponding to the extreme value of the spectrum curve as the excitation The high-energy state control signal frequency of the target qubit transition from |1> state to |2> state; the transition frequency of the target qubit transition from |1> state to |2> state is the high-energy state control signal frequency frequency. Since the frequency of the second control signal that resonates with the transition frequency of the target qubit from the |1> state to the |2> state is directly acquired in the implementation of the specification, the frequency of the high-energy state control signal is effectively improved measurement accuracy.

See Figure 10. In the implementation of this specification, when the wave parameter is frequency, the method for determining the qubit high-energy state control signal may include:

S501: Apply a first control signal to a target qubit, and control the target qubit to a |1> state.

S502: Apply the second control signal with a specific frequency of the frequency sweep point to the target qubit in the |1> state, wherein the second control signal can change the target qubit from |1 The > state transitions to the |2> state.

S503: Apply a third control signal to the target qubit again, where the parameters of the third control signal are the same as the parameters of the first control signal.

In this embodiment, the power, frequency, amplitude and width of the third control signal are the same as those of the first control signal.

In this implementation manner, the third control signal may be a π pulse capable of manipulating the target qubit to flip its quantum state between the |0> state and the |1> state.

Therefore, when the third control signal is applied to the target qubit, two results will be produced: first, if the second control signal does not excite and transition the target qubit to the |2> state, then The third control signal will flip the target qubit from the |1> state to the |0> state, then the read measurement result of the target qubit quantum state is the |0> state; The second control signal has excited the transition of the target qubit to the |2> state, then the third control signal will not have a control effect on the target qubit, and the target qubit is still in the |2> state state, then the reading measurement result of the quantum state of the target qubit is the |2> state.

S504: Determine whether the second control signals at all frequency scanning points have been applied to the target qubits; if yes, execute S505; if not, return to execute S501-S503.

S505: Obtain the spectrum curve of the target qubit.

In this embodiment, what is obtained is the quantum state of the target qubit manipulated by the third control signal. This step is basically the same as S403 in the above-mentioned embodiment of this specification. For details, please refer to the above-mentioned embodiment of this specification. , which will not be repeated here.

It should be noted that the frequency curve of the target qubit acquired through this embodiment and the frequency curve of the target qubit acquired in S403 of the above-mentioned embodiment have a difference between the magnitude or phase of the qubit reading feedback signal on the ordinate. Numerically different. What S403 acquires is the magnitude or phase value of the qubit read feedback signal when the target qubit is in |1> state or |2> state, and what S505 acquires is the When the target qubit is in the |0> state or the |2> state, the qubit reads the amplitude or phase value of the feedback signal.

S506: Obtain the frequency of the second control signal corresponding to the extremum of the frequency spectrum curve as the frequency of the high-energy state control signal for the target qubit to transition from the |1> state to the |2> state.

This implementation manner is basically the same as S404 in the above implementation manners of this specification. For details, please refer to the above implementation manners of this specification, and details are not repeated here.

It should be noted that the above S505 to S506 may be executed in parallel with the above S501 to S503, or may be executed after S503, which is not specifically limited in the implementation manner of this specification.

The method for determining the qubit high-energy state control signal provided in this embodiment, by applying the third control signal to the target qubit, on the one hand, because the ordinate of the obtained spectrum curve is that the target qubit is at |0 > state or |2> state, the qubit reads the amplitude or phase value of the feedback signal, which can further improve the resolution of the resonance peak extreme value of the spectrum curve, thereby effectively reducing the misjudgment rate of the result and improving the The measurement accuracy of the frequency of the high-energy state regulation signal; on the other hand, it can check the effect of the second regulation signal on the regulation effect of the target qubit, that is, when the second regulation signal When the target qubit is excited to the |2> state, the third control signal loses its control effect on the target qubit. Only when the target qubit is not excited to the |2> state by the second control signal, the third control signal can flip the target qubit from the |1> state back to the |0> state. Therefore, whether the second control signal has a control effect on the target qubit can be verified by measuring whether the target qubit is in the |0> state after being manipulated by the third control signal.

The implementation manner of this specification is described below in conjunction with a specific example. Assuming that the operating point frequency of the target qubit on a quantum chip is 4954MHz, and the anharmonicity is -250MHz, the theoretical value of the transition frequency from the |1> state to the |2> state is 4704MHz. Using the method of the embodiment of this specification, the second qubit is set according to the theoretical value and anharmonicity of the operating point frequency and anharmonicity of the target qubit or the transition frequency from the |1> state to the |2> state. The frequency scanning range of the control signal is [4579MHz, 4829MHz]. And select 25 frequency scanning points within the frequency scanning range. The timing of the measurement and control waveform signal shown in FIG. 11 is applied to the target qubit at each frequency scanning point of the second control signal. Wherein, in the waveform signal sequence, the first and third waveform signals of the regulation waveform signal sequence transmitted on the XY control line are the first regulation signal and the third regulation signal, and the intermediate waveform signal is the Second regulatory signal. Therefore, within the set frequency scanning range [4579MHz, 4829MHz], the measurement and control waveform signal sequence shown in Figure 11 is applied to the target qubit 25 times, and the spectrum curve of the target qubit is obtained as shown in Figure 12 Show. According to the measurement of the spectrum curve, the actual value of the frequency of the high-energy state control signal of the target qubit is 4697.093 MHz. Under the same parameter conditions, the actual value of the frequency of the high-energy state control signal of the target qubit obtained by the traditional indirect measurement method is 4680MHz. It can be seen that the actual value of the frequency of the high-energy state control signal of the target qubit obtained by using the method of the embodiment of this specification is very close to its theoretical value.

The following is an introduction to a device for determining a qubit high-energy state control signal provided in the embodiments of this specification. The determination device described below and the determination method described above can be referred to in correspondence.

Please refer to Figure 13. FIG. 13 is a structural block diagram of a device for determining a qubit high-energy state regulation signal provided by an embodiment of the present specification. The device for determining the qubit high-energy state regulation signal may include:

The control module 001 is used to adjust the wave parameters of the second control signal within the preset wave parameter scanning range, and apply the first control signal and the adjusted second control signal to the target qubit in sequence, so that The target qubit transitions from the first excited state to the second excited state; wherein the first control signal is used to control the target qubit to flip between the first excited state and the ground state;

The parameter acquisition module 002 is configured to acquire the wave parameter of the second control signal that causes the target qubit to transition from the first excited state to the second excited state, as the wave parameter of the high-energy state control signal.

The device for determining the qubit high-energy state control signal in the embodiment of this specification is used to realize the aforementioned determination method for the qubit high-energy state control signal. The implementation part of the method for determining the state control signal, for example, the control module 001 and the parameter acquisition module 002 are respectively used to implement S101 and S102 in the method for determining the high-energy state control signal of the qubit. Therefore, the specific implementation methods can refer to the corresponding The description of each implementation manner will not be repeated here.

The embodiment of this specification also provides a quantum computer, the quantum computer includes the device for determining the qubit high-energy state control signal in the above embodiment of this specification, or uses any of the above-mentioned ones introduced in the implementation of this specification The method for determining the high-energy state control signal of the qubit determines the high-energy state control signal of the qubit. For the rest of the content, reference may be made to the prior art, and no further description is given here.

The following is an introduction to an electronic device provided by an embodiment of this specification. The electronic device described below can be referred to in correspondence with the method for determining a qubit high-energy state control signal and the device for determining a qubit high-energy state control signal described above.

Please refer to Figure 14. FIG. 14 is a structural block diagram of an electronic device provided by an embodiment of this specification. The electronic device may include a processor 11 and a memory 12 .

The memory 12 is used to store computer programs; the processor 11 is used to implement the above-mentioned embodiments of this specification when executing the computer programs. The method for determining the qubit high-energy state control signal described in the embodiment.

The processor 11 in the device for determining the qubit high-energy state control signal in this embodiment is used to install the device for determining the qubit high-energy state control signal described in the implementation mode of this specification. At the same time, the combination of the processor 11 and the memory 12 can realize The method for determining the qubit high-energy state regulation signal described in any of the above-mentioned embodiments of this specification. Therefore, the specific implementation of the device for determining the qubit high-energy state control signal can be seen in the implementation part of the method for determining the qubit high-energy state control signal above. Let me repeat.

The present application also provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, a quantum A method for determining a bit high-energy state regulation signal. For the rest of the content, reference may be made to the prior art, and no further description is given here.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for relevant details, please refer to the description of the method part.

Those skilled in the art can further appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the hardware and software In the above description, the components and steps of each example have been generally described according to their functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present application.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be directly implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other Any other known storage medium.

Finally, it should also be noted that in this text, relational terms such as first and second etc. are only used to distinguish one entity or operation from another, and do not necessarily require or imply that these entities or operations, any such actual relationship or order exists. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

It should be noted that the terms "first excited state", "second excited state" and "third excited state" in the full text are commonly used technical terms in this field, and they are titles in order of energy levels, with definite energy levels. The first excited state refers to the first excited state energy level adjacent to the ground state, the second excited state refers to the second excited state energy level adjacent to the first excited state, and the third excited state refers to the adjacent excited state energy level. The third excited state energy level of the second excited state, and so on.

The above is a method for determining a qubit high-energy state control signal, a device for determining a qubit high-energy state control signal, a quantum computer, an electronic device, and a computer-readable storage medium provided by the embodiments of this specification. gave a detailed introduction. In this paper, specific examples are used to illustrate the principles and implementation methods of the present application, and the descriptions of the above embodiments are only used to help understand the methods and core ideas of the present application. It should be pointed out that those skilled in the art can make some improvements and modifications to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims (26)

1. A method for determining a qubit high-energy state regulation signal, characterized in that it includes:

   Adjust the wave parameter of the second control signal within the preset wave parameter scanning range, and apply the first control signal and the adjusted second control signal to the target qubit in sequence, so that the target qubit is changed from the first control signal to the target qubit. The excited state transitions to a second excited state; wherein the first control signal is used to control the target qubit to flip between the first excited state and the ground state;

   Obtaining the wave parameter of the second control signal that causes the target qubit to transition from the first excited state to the second excited state is used as the wave parameter of the high-energy state control signal.
2. The method according to claim 1, wherein the wave parameter is an amplitude; the wave parameter of the second control signal is adjusted within the preset wave parameter scanning range, and the wave parameters are respectively applied to the target qubits in sequence. The step of the first control signal and the adjusted second control signal to make the target qubit transition from the first excited state to the second excited state includes:

   Adjust the amplitude of the second control signal within the preset amplitude scanning range, and apply the first control signal, the The second control signal and the first control signal are subjected to a Rabi oscillation experiment, and the first signals corresponding to the target qubits are obtained respectively, wherein the first signals are measured and include final state information of the target qubits signal of;

   The step of obtaining the wave parameters of the second control signal that causes the target qubit to transition from the first excited state to the second excited state as the wave parameters of the high-energy state control signal includes: based on all the first signals For amplitude data or phase data, the amplitude of the second control signal corresponding to when the target qubit is in the second excited state is obtained as the amplitude of the high-energy state control signal.
3. The method according to claim 2, wherein the obtaining the first signal corresponding to the target qubit comprises:

   Each of the first signals is obtained by reading a waveform signal; the frequency of the read waveform signal is set to the cavity frequency of a read resonant cavity coupled with the target qubit when the target qubit is in a ground state.
4. The method according to claim 2, characterized in that, after each adjustment of the amplitude of the second control signal, the first control signal, the second control signal, and the target qubit are sequentially applied. During the Rabi oscillation experiment of the first control signal, the second control signal and the first control signal are output through the same signal output channel.
5. The method according to claim 2, characterized in that, in the adjusting the amplitude of the second regulation signal within the preset amplitude scanning range, the amplitude scanning range is based on the first regulation The amplitude of the signal is determined, and the amplitude of the second control signal is greater than the amplitude of the first control signal.
6. The method according to claim 5, wherein the adjusting the amplitude of the second regulation signal within the preset amplitude scanning range comprises:

   selecting an initial amplitude within the preset amplitude scanning range, and increasing or decreasing the initial amplitude based on a preset step size to obtain the adjusted amplitude;

   Iteratively updating the adjustment amplitude based on the step size; wherein the adjustment amplitude is used as the amplitude of the second control signal.
7. The method according to claim 2, wherein the second regulation corresponding to when the target qubit is in the second excited state is acquired based on the amplitude data or phase data of all the first signals The amplitude of the signal is used as the amplitude of the high-energy state control signal, and the amplitude of the second control signal corresponding to the qubit in the second excited state is the same as the amplitude data of all the first signals or The extremum of the phase data corresponds to the amplitude of the second control signal.
8. The method according to claim 2, wherein the second control signal corresponding to when the target qubit is in the second excited state is obtained based on the amplitude data or phase data of all the first signals magnitudes, including:

   fitting the amplitude data or the phase data to obtain amplitude fitting data or phase fitting data;

   Identifying the extremum of the amplitude fitting data or phase fitting data, and obtaining the amplitude of the second regulation signal corresponding to the extremum as the second regulation corresponding to when the qubit is in the second excited state The amplitude of the signal.
9. The method according to claim 2, wherein the determining method further comprises:

   The power and pulse width of the second regulation signal are determined based on the power and pulse width of the first regulation signal.
10. The method according to claim 9, wherein the determining the power and pulse width of the second control signal based on the power and pulse width of the first control signal comprises:

    The power and pulse width of the second control signal are the same as the power and pulse width of the first control signal.
11. The method according to claim 2, wherein the determining method further comprises:

    The working frequency of the second regulating signal is determined based on the working frequency of the first regulating signal.
12. The method according to claim 2, wherein the determining method further comprises:

    The operating frequency of the second control signal is acquired based on the frequency spectrum curve of the target qubit.
13. The method according to claim 1, wherein the wave parameter is frequency; the wave parameter of the second control signal is adjusted within the preset wave parameter scanning range, and the first control is applied to the target qubits respectively in sequence signal and the adjusted second control signal, to the step of making the target qubit transition from the first excited state to the second excited state, comprising:

    Applying a first control signal to the target qubit to control the target qubit to a first excited state;

    Adjust the frequency of the second control signal within the preset frequency scanning range, and then apply the adjusted second control signal to the target qubit, wherein the second control signal can move the target qubit from transition from the first excited state to the second excited state;

    The step of obtaining the wave parameters of the second control signal that causes the target qubit to transition from the first excited state to the second excited state as the wave parameters of the high-energy state control signal includes:

    Obtain the spectrum curve of the target qubit;

    The frequency of the second control signal corresponding to the extremum value of the frequency spectrum curve is the frequency of the high-energy state control signal for the target qubit to transition from the first excited state to the second excited state.
14. The method according to claim 13, wherein the frequency of the second control signal is adjusted within the preset frequency scanning range, and the adjusted second control signal is applied to the target qubit, The frequency scanning range does not include the operating point frequency of the target qubit.
15. The method according to claim 13, wherein the frequency of the second control signal is adjusted within the preset frequency scanning range, and the adjusted second control signal is applied to the target qubit, The frequency scanning range is set based on the operating point frequency and anharmonicity of the target qubit.
16. The method according to claim 15, wherein the frequency scanning range is Wherein, f ₀₁ is the operating point frequency of the target qubit, and α is the anharmonicity of the target qubit.
17. The method according to claim 13, wherein the first control signal is applied to the target qubit, and the target qubit is regulated to the first excited state; the first excited state is adjusted within the preset frequency scanning range. The frequency of the second regulation signal, and in the adjusted second regulation signal applied to the target qubit, the amplitude of the second regulation signal is larger than the amplitude of the first regulation signal, and the second The driving power of the regulation signal is the same as the driving power of the first regulation signal.
18. The method according to claim 17, wherein the first control signal is applied to the target qubit, and the target qubit is regulated to the first excited state; the first excited state is adjusted within the preset frequency scanning range. The frequency of the second control signal is applied to the target qubit and the adjusted second control signal is applied, and the first control signal and the second control signal are output by the same signal channel.
19. The method according to claim 13, wherein the first control signal is applied to the target qubit to control the target qubit into a first excited state, and the frequency of the first control signal is the same as The operating point frequencies of the target qubits are the same.
20. The method according to claim 19, characterized in that, the step of adjusting the frequency of the second control signal within the preset frequency scanning range, and then applying the adjusted second control signal to the target qubit ,include:

    The second control signal is generated by the second baseband waveform signal; the frequency variation range of the second baseband waveform signal is Wherein, IF is the frequency of the first baseband waveform signal used to generate the first regulation signal, and the first baseband waveform signal and the second baseband waveform signal are generated by a signal generator.
21. The method according to any one of claims 13-20, wherein the determining method further comprises:

    After applying the second control signal to the target qubit, apply a third control signal to the target qubit, wherein the parameters of the third control signal are the same as those of the first control signal The parameters are the same.
22. The method according to claim 21, wherein both the first control signal and the third control signal are capable of manipulating the target qubit to make its quantum state flip between the ground state and the first excited state π pulse.
23. A device for determining a qubit high-energy state control signal, characterized in that the device for determining includes:

    The control module is used to adjust the wave parameters of the second control signal within the preset wave parameter scanning range, and apply the first control signal and the adjusted second control signal to the target qubit in sequence, so as to make the target The qubit transitions from the first excited state to the second excited state; wherein the first control signal is used to control the target qubit to flip between the first excited state and the ground state;

    A parameter acquisition module, configured to acquire the wave parameter of the second control signal that causes the target qubit to transition from the first excited state to the second excited state, as the wave parameter of the high-energy state control signal.
24. A quantum computer, characterized in that it comprises the device as claimed in claim 23 or uses the above-mentioned claim 1-22 The method described in any one determines the high-energy state control signal of the qubit.
25. A computer storage medium, wherein a computer program is stored in the computer storage medium, wherein the computer program is configured to execute the method according to any one of claims 1-22 when running.
26. An electronic device, characterized by comprising 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 the Methods.