Patent Application
20240289289
The present application belongs to the field of quantum measurement and control technologies, and in particular, to a method and an apparatus for determining a measurement result of multiple qubits, and a quantum computer.
Qubit information refers to a quantum state of a qubit, and basic quantum states are state |0 and state |1
. After the qubit is operated, the quantum state of the qubit changes. In a quantum chip, after the quantum chip is executed, a quantum state of a qubit changes, and the change is an execution result of the quantum chip. The execution result is carried in a qubit readout signal (generally an analog signal) and sent out.
A process of rapidly measuring a quantum state of a qubit by using a qubit readout signal is a key work for reflecting execution performance of a quantum chip. High accuracy of a qubit measurement result is always an important index continuously pursued in the quantum computing industry. In conventional technologies, a relatively mature manner is determining the index by using a measurement result of a single qubit that is not affected by other qubits. However, a plurality of associated qubits have a more practical and extensive application prospect. For example, the application may include running a dual quantum logic gate by using two associated qubits or running a plurality of associated qubits by using a plurality of quantum logic gates. For another example, the application may include running a quantum computing task by using a plurality of associated qubits. In these examples, determination of measurement results of a plurality of associated qubits is of particular importance. Up to now, there is no relevant technique regarding a method for determining measurement results of a plurality of associated qubits. Therefore, how to implement measurement on a plurality of associated qubits and also ensure accuracy of measurement results is a problem to be solved urgently at present.
An objective of the present disclosure is to provide a method and an apparatus for determining a measurement result of multiple qubits, and a quantum computer, to solve a problem in conventional technologies that measurement results of a plurality of associated qubits cannot be accurately determined, so that a plurality of associated qubits may be applied.
According to a first aspect, the present disclosure provides a method for determining a measurement result of multiple qubits, a plurality of sequentially arranged qubits and a plurality of readout data buses are disposed on a quantum chip, each readout data bus is coupled to a plurality of qubits, and the determining method includes: separately acquiring, based on a sequence number of each to-be-read qubit, a readout feedback signal of a data bus corresponding to the to-be-read qubit; acquiring quantum state information of each to-be-read qubit based on the corresponding readout feedback signal; separately acquiring a quantum state measurement value of each to-be-read qubit based on the corresponding quantum state information and a readout criterion of the to-be-read qubit, where the readout criterion is used to identify a quantum state of the corresponding to-be-read qubit, and the quantum state includes a first quantum state and a second quantum state; and determining a measurement result target value of to-be-read qubits based on an information weight and the quantum state measurement value of each to-be-read qubit, where the information weight of each to-be-read qubit is determined based on the sequence number of the to-be-read qubit and a quantity of to-be-read qubits.
The present disclosure further provides a method and an apparatus for optimizing a parameter of a plurality of qubits readout signal, and a quantum computer, to solve a defect and a deficiency in a conventional technology. A parameter of a readout signal of associated multiple qubits may be optimized to ensure accuracy of a measurement result, so that a plurality of qubits may be applied.
According to a second aspect, the present disclosure provides a method for optimizing a parameter of a plurality of qubits readout signal, a plurality of sequentially arranged qubits and a plurality of readout data buses are disposed on a quantum chip, each readout data bus is coupled to a plurality of qubits, and the method for optimizing a parameter includes: separately setting a parameter of a readout signal corresponding to each to-be-read qubit based on the to-be-read qubit, where to-be-read qubits located on a same readout data bus have a same readout signal, the readout signal is obtained based on mixing of intermediate frequency signals, and the intermediate frequency signal includes modulation and coding information required by a qubit for quantum computing; separately applying the readout signal to a corresponding readout data bus to obtain a corresponding readout feedback signal; acquiring measurement data of each to-be-read qubit based on the readout feedback signal, where the measurement data is scatter point data in an IQ coordinate system; and separately optimizing, based on a distribution feature of measurement data of each to-be-read qubit in the IQ coordinate system, the parameter of the readout signal corresponding to each to-be-read qubit.
According to a third aspect, the present disclosure provides an apparatus for determining a measurement result of multiple qubits, including: a first acquisition module, configured to acquire a sequence number of each to-be-read qubit and a quantity of to-be-read qubits; a second acquisition module, configured to separately acquire, based on a sequence number of each to-be-read qubit, a readout feedback signal of a data bus corresponding to the to-be-read qubit; a third acquisition module, configured to acquire quantum state information of each to-be-read qubit based on the corresponding readout feedback signal; a fourth acquisition module, configured to separately acquire a quantum state measurement value of each to-be-read qubit based on the corresponding quantum state information and a readout criterion of the to-be-read qubit; and a determining module, configured to determine a measurement result target value of to-be-read qubits based on an information weight and the quantum state measurement value of each to-be-read qubit.
According to a fourth aspect, the present disclosure provides an apparatus for optimizing a parameter of a multi-qubit readout signal, including: a setting module, configured to separately set a parameter of a readout signal corresponding to each to-be-read qubit based on the to-be-read qubit; an application module, configured to separately apply the readout signal to a corresponding readout data bus to obtain a corresponding readout feedback signal; an acquisition module, configured to acquire measurement data of each to-be-read qubit based on the corresponding readout feedback signal; and an optimization module, configured to separately optimize, based on a distribution feature of the measurement data of each to-be-read qubit in the IQ coordinate system, the parameter of the readout signal corresponding to the to-be-read qubit.
According to a fifth aspect, the present disclosure provides a quantum computer, to which the method for determining a measurement result of multiple qubits according to the first aspect or the method for optimizing a parameter of a multi-qubit readout signal according to the second aspect is applied, or including the apparatus for determining a measurement result of multiple qubits according to the third aspect or the apparatus for optimizing a parameter of a multi-qubit readout signal according to the fourth aspect.
In an embodiment, measurement results of a plurality of associated qubits may be determined, so that the plurality of associated qubits may be applied, practicality of the plurality of associated qubits is improved, and an application scenario of the plurality of associated qubits is expanded.
In another embodiment, a parameter of a readout signal of associated multiple qubits may be optimized to ensure accuracy of a measurement result, so that the plurality of associated qubits may be applied, practicality of the plurality of associated qubits is improved, and an application scenario of the plurality of associated qubits is expanded.
To describe the technical solutions in the embodiments of the present disclosure or in the conventional technology more clearly, the following briefly describes the accompanying drawings required for describing the embodiments or the conventional technology. Apparently, the accompanying drawings in the following description only show some embodiments of the present disclosure, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.
The following further describes in detail a method and an apparatus for determining a measurement result of multiple qubits, and a quantum computer proposed in the present disclosure with reference to the accompanying drawings and specific embodiments. The advantages and features of the present disclosure will be more apparent from the following description. It should be noted that, the accompanying drawings all use a very simplified form and a non-accurate proportion for conveniently and clearly assisting in description of the embodiments of the present disclosure.
In the description of the present disclosure, the terms “first” and “second” are merely intended for a purpose of description, and shall not be understood as an indication or implication of relative importance or implicit indication of the number of indicated technical features. Therefore, the features defined by “first” and “second” may indicate or imply that one or more of the features are included. In the descriptions of the present disclosure, “a plurality of” means at least two, for example, two or three, unless otherwise specifically stated.
A method provided in the embodiments may be executed in a computer terminal or a similar operation apparatus. For example. a method is run on a computer terminal. Referring to
The memory 104 may be configured to store a software program and a module of application software, for example, a program instruction/module corresponding to a method for determining a measurement result of multiple qubits or a method for optimizing a parameter of a readout signal of a plurality of qubits provided in the present application. The processor 102 executes various function applications and data processing by running the software program and the module that are stored in the memory 104, that is, implements the foregoing method. The memory 104 may include a high-speed random access memory, and may further include a non-volatile solid-state memory. In some embodiments, the memory 104 may further include a memory 104 remotely disposed relative to the processor 102, which may be connected to a computer terminal over a network. Examples of the network include but are not limited to the Internet, a corporate intranet, a local area network, a mobile communication network, and a combination thereof.
The transmission apparatus 106 is configured to receive or send data over a network. A specific example of the network may include a wireless network provided by a communication provider of a computer terminal. In an embodiment, the transmission apparatus includes a network interface controller (Network Interface Controller, NIC) that may be connected to another network device by using a base station, so as to communicate with the Internet. In an embodiment, the transmission apparatus 106 may be a radio frequency (Radio Frequency, RF) module. The radio frequency module is configured to communicate with the Internet in a wireless manner.
The method provided in the embodiments may be applied to the foregoing computer terminal, which is also referred to as a quantum computer.
In the quantum computer, a quantum chip is a processor for executing quantum computing. Referring to
Control and processing processes of qubits are described as follows.
A frequency of a qubit is adjusted to an operating frequency by using a magnetic flux control signal on the Z signal transmission line. In this case, a quantum state control signal is applied by using the XY signal transmission line to perform quantum state control on a qubit that is in an initial state. A quantum state of the qubit obtained after the control is read out by using a readout resonant cavity. Specifically, a readout signal transmission line is used to apply a carrier pulse signal, which is generally referred to as a readout sounding signal. The readout sounding signal is generally a microwave signal with a frequency ranging from 4 GHz to 8 GHz. The quantum state of the qubit is determined by parsing a readout feedback signal output by the readout signal transmission line. A reason why a readout resonant cavity can read a quantum state of a qubit is that different quantum states of the qubit have different dispersion shifts to the readout resonant cavity, so that different quantum states of the qubit have different responses to a readout sounding signal applied to the readout resonant cavity. The response signal is referred to as a readout feedback signal. Only when a carrier frequency of the readout sounding signal of the qubit is very close to a natural frequency (also referred to as a resonance frequency) of the readout resonant cavity, the readout resonant cavity has an obviously different response to the readout sounding signal due to different quantum states of the qubit, that is, the readout feedback signal has a maximum distinguishability. Based on this, a quantum state in which the qubit is located is determined by parsing a readout feedback signal of a specific pulse length. For example, a readout feedback signal collected each time is converted into a coordinate point in an orthogonal plane coordinate system (namely, an I-Q plane coordinate system). It is determined, based on a position of the coordinate point, whether a corresponding quantum state is state |0 or state |1
. It may be understood that the state |0
and state |1
are two eigenstates of a qubit.
The present disclosure provides a method and an apparatus for determining a measurement result of multiple qubits, and a quantum computer, to determine measurement results of a plurality of associated qubits, so that the plurality of associated qubits may be applied, practicality of the plurality of associated qubits is improved, and application scenarios of the plurality of associated qubits are expanded.
Therefore, the embodiment provides a method for determining a measurement result of multiple qubits. A plurality of sequentially arranged qubits and a plurality of readout data buses are disposed on a quantum chip, and each readout data bus is coupled to a plurality of qubits. Referring to
For example, parameters of readout signals of a plurality of qubits may be optimized. Parameters of readout signals of a plurality of associated qubits may be optimized to ensure accuracy of measurement results, so that the plurality of associated qubits may be applied, practicality of the plurality of associated qubits is improved, and an application scenario of the plurality of associated qubits is expanded. Referring to
Readout signals of to-be-read qubits located on a same readout data bus have a same local oscillator signal. The readout signals are obtained by mixing an intermediate frequency signal with the local oscillator signal. The intermediate frequency signal includes modulation and coding information required by qubits for quantum computing.
According to an embodiment, a sequence number of each to-be-read qubit and a quantity of to-be-read qubits are acquired. For example, a size of 24-bit quantum chip is used as an example. Referring to
In this embodiment, it may be learned from the foregoing description that, when a read operation is performed, readout signals corresponding to two to-be-read qubits Q0 and Q1 are applied to the readout data bus BUS1 to acquire corresponding readout feedback signals; and a readout signal corresponding to the to-be-read qubit Q17 is applied to the readout data bus BUS3 to acquire a corresponding readout feedback signal.
It may be learned from the foregoing description that the readout data bus corresponding to the two to-be-read qubits Q0 and Q1 is BUS1, and a readout data bus corresponding to the to-be-read qubit Q17 is BUS3. Correspondingly, readout feedback signals of the readout data buses BUS1 and BUS3 are acquired.
The readout feedback signal is an analog signal, representing a signal of quantum state information for a to-be-read qubit coupled thereto. The measurement data that can represent each piece of quantum state information may be obtained by applying different carrier pulse signals (read sounding signals) to a corresponding to-be-read qubit and repeating the process, where the measurement data is scatter point data in an IQ coordinate system.
Theoretically, in an ideal case, the measurement data obtained by applying different carrier pulse signals (read sounding signals) to a corresponding to-be-read qubit and repeating the process is distributed in the IQ coordinate system into two circular spots, which respectively represent two different ground states of the to-be-read qubits, to be specific, state |0 and state |1
. However, after a large quantity of repeated experiments, it is found that in a measurement process, the obtained measurement data is distributed in the IQ coordinate system into two quasi-circles, as shown in
in the figure is distributed in the measurement data of the state |1
; and a small part of measurement data corresponding to state |1
in the figure is distributed in the measurement data of the state |0
. This indicates that there is a case in the experiment that destroys distribution of the quantum states of the to-be-read qubits. Therefore, a parameter of a corresponding readout signal needs to be optimized, to make distribution of the quantum states of the to-be-read qubits more idealized.
The readout feedback signal is obtained from a readout data bus, and represents a signal of quantum state information for a to-be-read qubit coupled to the readout data bus. It should be noted that, the readout feedback signal is an analog signal, and a form of the analog signal includes but is not limited to: S=Acos(ωt+φ)=A/2[e−i(ωt+φ)+ei(ωt+φ)]. A person skilled in the art may understand that the form is a general representation of the analog signal, and therefore, parameters in the formula are not described herein. Digital processing, including but not limited to frequency mixing and/or integration processing, is performed on the signal to obtain corresponding complex signal that includes quantum state information. In this embodiment, quantum state information of two to-be-read qubits Q0 and Q1 may be obtained based on the readout feedback signal obtained from the readout data bus BUS1. Quantum state information of the to-be-read qubit Q17 may be obtained based on the readout feedback signal obtained from the readout data bus BUS3.
It should be noted that the readout criterion is obtained by means of machine training. A specific training process is as follows.
A carrier pulse signal (readout sounding signal) is applied to a to-be-trained qubit, and a readout feedback signal output by a readout data bus corresponding to the to-be-trained qubit is measured to obtain corresponding quantum state information and the corresponding quantum state information is recorded. Different carrier pulse signals (read sounding signals) are applied and the process is repeated, to obtain a measurement result that can represent each piece of quantum state information, and the readout criterion is generated based on the measurement result, to subsequently identify a quantum state of a corresponding to-be-read qubit. The quantum state includes a first quantum state and a second quantum state. In this embodiment, the first quantum state and the second quantum state are respectively state |0 and state |1
.
In a specific application, as long as the obtained quantum state information is input into the readout criterion, a quantum state measurement value of a corresponding to-be-read qubit may be acquired, so as to implement a quantum state identification process of the to-be-read qubit, thereby reducing of quantum computing steps and improving quantum computation efficiency.
For example, the readout criterion is one of a linear straight line equation or a curve equation.
For example, the information weight of each to-be-read qubit is determined based on a sequence number of the to-be-read qubit and a quantity of to-be-read qubits. In this embodiment, an order of a bit position of each to-be-read qubit is set to be corresponding to a size of sequence number of the to-be-read qubit. For example, a measurement result formed by three to-be-read qubits Q0, Q1, and Q17 is Q17 Q1 Q0. Then, the measurement result is converted into measurement result eigenvalues. Finally, a measurement result eigenvalue with a largest occurrence probability in the measurement result eigenvalues is used as the measurement result target value of the to-be-read qubits.
For example, referring to
In this embodiment, according to the foregoing description, the measurement result formed by the three to-be-read qubits Q0, Q1, and Q17 is Q17 Q1 Q0, and the measurement result is converted into measurement result eigenvalues, with a total of eight values ranging from |000 to |111
.
After a plurality of measurements, a probability value of occurrence of the measurement result eigenvalues |000, |001
, . . . , |111
is collected, and the eight probability values form a probability matrix of 8*1, which is denoted as M.
For example, a maximum value in the probability matrix is determined, and a measurement result eigenvalue corresponding to the maximum value is used as the measurement result target value of the to-be-read qubits.
For example, after the acquiring a probability matrix of the measurement result eigenvalues, the method further includes the following steps.
In the foregoing description of the training process of the readout criterion, fidelity values of the readout criterion may be simultaneously obtained after a large quantity of experiments. Fidelity is a parameter that represents a degree of similarity between an input signal and an output signal obtained by reproducing the input signal and output by an electronic device. In the field of quantum measurement and control and quantum computing, the higher the fidelity, the more accurate the results of quantum measurement and control and quantum computing. In this embodiment, the fidelity of the readout criterion is a probability value of quantum state measurement values of a corresponding to-be-read qubit obtained when the acquired quantum state information is input into the readout criterion.
The union fidelity matrix may then be determined based on the sequence number and the fidelity of the readout criterion of each to-be-read qubit. It is not difficult to understand that a size of the union fidelity matrix is the same as a size of the foregoing probability matrix, that is, the two matrices have same quantity of rows and columns. Numerical values in the union fidelity matrix represent theoretical probability values of occurrence of measurement result eigenvalues based on the fidelity of the readout criterion of each to-be-read qubit. For example, in this embodiment, fidelity of a readout criterion of a to-be-read qubit Q0 is 0.9 (a quantum state of Q0 is state |0), fidelity of a readout criterion of a to-be-read qubit Q1 is 0.3 (a quantum state of Q1 is state |0
), and fidelity of a readout criterion of a to-be-read qubit Q17 is 0.8 (a quantum state of Q17 is state |0
). An acquired theoretical probability value of occurrence of a measurement result eigenvalue |000
of the measurement result Q17 Q1 Q0 may be 0.216 (0.9*0.3*0.8). Similarly, theoretical probability values of occurrence of remaining measurement result eigenvalues may be separately acquired. Then, theoretical probability values of occurrence of the eight measurement result eigenvalues form a union fidelity matrix of 8*1, which is denoted as F.
For example, the determining a measurement result target value of the to-be-read qubits based on the measurement result eigenvalues and the probability matrix of the measurement result eigenvalues includes: determining the measurement result target value of the to-be-read qubits based on the measurement result eigenvalue and a corrected probability matrix. Referring to
In this embodiment, after the probability matrix is corrected, a contingency error of each probability value in the original probability matrix may be eliminated, so that each probability value in the corrected probability matrix is more accurate, and the measurement result target value obtained is more accurate.
For example, referring to
First, the fidelity of the readout criterion of each to-be-read qubit is acquired. Then, an error rate of the readout criterion of each to-be-read qubit is determined based on the fidelity. Finally, a fidelity matrix of the readout criterion of each to-be-read qubit is determined based on the fidelity and the error rate. For example, an acquired fidelity of the readout criterion of a to-be-read qubit Q0 is 0.9 (a quantum state of Q0 is state |0). The error rate of the readout criterion of the to-be-read qubit Q0 is 0.1 (a quantum state of Q0 is not state |0
), and it may be determined that a fidelity matrix of a readout criterion of the to-be-read qubit Q0 is a one-row two-column fidelity matrix formed by the fidelity of the readout criterion and the error rate of the readout criterion of the to-be-read qubit Q0. Similarly, a fidelity matrix of a readout criterion of another to-be-read qubit may be obtained.
The fidelity and the error rate of the readout criterion of each to-be-read qubit may be learned based on the fidelity matrix of the readout criterion of the to-be-read qubit. Then, the union fidelity matrix may be obtained by performing direct product processing on the fidelity of the readout criterion or the error rate of the to-be-read qubit based on the sequence number and measurement result eigenvalues of each to-be-read qubit. For example, one measurement result eigenvalue of the measurement result Q17 Q1 Q0 is |000. A value of the union fidelity matrix may be obtained by performing direct product processing on fidelity of readout criterion of the three to-be-read qubits Q0, Q1, and Q17. Similarly, other values of the union fidelity matrix may be obtained.
For example, referring to
For example, during obtaining of the probability matrix of the measurement result eigenvalues, a random error may occur, and an actual measurement result frequency value is affected, which may be corrected by using the following formula:
Based on a same application concept, the embodiment further provides an apparatus for determining a measurement result of multiple qubits. Referring to
A first acquisition module 510, configured to acquire a sequence number of each to-be-read qubit and a quantity of to-be-read qubits;
A second acquisition module 520, configured to separately acquire, based on a sequence number of each to-be-read qubit, a readout feedback signal of a data bus corresponding to the to-be-read qubit;
A third acquisition module 530, configured to acquire quantum state information of each to-be-read qubit based on the corresponding readout feedback signal;
A fourth acquisition module 540, configured to separately acquire a quantum state measurement value of each to-be-read qubit based on the corresponding quantum state information and a readout criterion of the to-be-read qubit; and
A determining module 550, configured to determine a measurement result target value of to-be-read qubits based on an information weight and the quantum state measurement value of each to-be-read qubit.
In addition, based on a same application concept, an embodiment further provides a quantum computer, configured to perform quantum computing by using the foregoing method for determining a measurement result of multiple qubits, or including the foregoing apparatus for determining a measurement result of multiple qubits.
In conclusion, measurement results of a plurality of associated qubits may be determined, so that the plurality of associated qubits may be applied, practicality of the plurality of associated qubits is improved, and an application scenario of the plurality of associated qubits is expanded.
For example, referring to
When the frequency of the readout signal is separately determined, readout frequencies of all qubits coupled to a readout data bus corresponding to each to-be-read qubit may be separately obtained. Then the frequency of the corresponding readout signal is separately determined based on the readout frequencies of all qubits on the readout data bus. A median bit of the readout frequencies of the qubits may be separately determined based on the readout frequencies of all qubits on the readout data bus, and then the median bit of the readout frequencies of the qubits is set to a frequency of a readout signal of a corresponding readout data bus. For example, in this embodiment, setting of a frequency of a readout signal corresponding to the to-be-read qubit Q17 is used as an example. First, readout frequencies of all qubits (that is, qubits with sequence numbers of 12 to 17) coupled to a readout data bus of the to-be-read qubit Q17 is acquired, then the six readout frequencies are arranged in a sequence of values, and an average value of two values in the middle is obtained as the frequency of the readout signal corresponding to the to-be-read qubit Q17
When the frequency of the intermediate frequency signal corresponding to the to-be-read qubit is separately determined, the frequency of the intermediate frequency signal corresponding to the to-be-read qubit may be separately determined based on a first preset relationship. The frequency of the intermediate frequency signal corresponding to the to-be-read qubit, the frequency of the readout signal, a readout frequency corresponding to the to-be-read qubit, and a preset frequency of the intermediate frequency signal meet the first preset relationship. For example, the first preset relationship is If′=Fc-Fc′+If, where If is a frequency of the intermediate frequency signal corresponding to the to-be-read qubit, Fc is a frequency of the readout signal, Fc′ is a readout frequency corresponding to the corresponding to-be-read qubit, and If is a preset frequency of the intermediate frequency signal.
When an amplitude of the intermediate frequency signal corresponding to the to-be-read qubit is separately determined, the amplitude of the intermediate frequency signal corresponding to the to-be-read qubit may be separately determined based on a second preset relationship. The amplitude of the intermediate frequency signal corresponding to the to-be-read qubit, a preset amplitude of the intermediate frequency signal, the power of the readout signal, and a readout power corresponding to the to-be-read qubit meet the second preset relationship. For example, the second preset relationship is: Amp′=Amp×10{circumflex over ( )}[(Pc′−10 dB−Pc)/2], where Amp′ is an amplitude of the intermediate frequency signal corresponding to the to-be-read qubit, Amp is a readout waveform amplitude corresponding to the to-be-read qubit, Pc′ is a power of the readout signal, and Pc is a readout power corresponding to the to-be-read qubit.
For example, referring to
Preferably, the criterion is a straight line represented as I=Q in the IQ coordinate system. For example, the criterion is used to reflect a distribution feature of measurement data of each to-be-read qubit in the IQ coordinate system.
If the measurement data of each to-be-read qubit does not meet the preset condition, Step S243 is performed, that is, separately optimizing the parameter of the readout signal corresponding to each to-be-read qubit.
For example, the preset condition includes a first preset condition, and whether measurement data of each to-be-read qubit meets the preset condition is determined based on the criterion. If the measurement data of each to-be-read qubit does not meet the preset condition, the separately optimizing the parameter of the readout signal corresponding to the to-be-read qubit may include the following steps.
Whether the measurement data of each to-be-read qubit meets a first preset condition is separately determined based on the criterion. The first preset condition is that measurement data obtained in a measurement process is distributed in an IQ coordinate system into two stable and clear quasi-circles (namely, two stable quasi-circles) respectively located on both sides of the criterion.
If the measurement data of each to-be-read qubit does not meet the first preset condition, an amplitude of an intermediate frequency signal corresponding to the to-be-read qubit is reduced according to a preset step within a preset range and the readout signal is updated. The amplitude of the intermediate frequency signal corresponding to each to-be-read qubit ranges from 0 V to 1 V.
For example, the preset condition further includes a second preset condition. After whether the measurement data of each to-be-read qubit meets the first preset condition is separately determined based on the criterion, the following steps are further included.
If the measurement data of each to-be-read qubit meets the first preset condition, whether the measurement data of each to-be-read qubit meets a second preset condition is separately determined based on the criterion. The second preset condition is that measurement data obtained in a measurement process is distributed in the IQ coordinate system into two quasi-circles, located on both sides of the criterion, with boundaries not intersected (namely, two separated quasi-circles).
If the measurement data of each to-be-read qubit does not meet the first preset condition, a frequency of an intermediate frequency signal corresponding to the to-be-read qubit is reduced or increased according to a preset step within a preset range and the readout signal is updated.
For example, the preset condition further includes a third preset condition. After whether the measurement data of each to-be-read qubit meets the second preset condition is separately determined based on the criterion, the following steps are further included.
If the measurement data of each to-be-read qubit meets the second preset condition, whether the measurement data of each to-be-read qubit meets the third preset condition is separately determined based on the criterion. The third preset condition is that measurement data obtained in a measurement process is distributed in the IQ coordinate system into two quasi-circles with high concentration located on both sides of the criterion (namely, two quasi-circles with high fidelity).
If the measurement data of each to-be-read qubit does not meet the second preset condition, a frequency and/or an amplitude of an intermediate frequency signal corresponding to the to-be-read qubit are/is reduced or increased according to a preset step within a preset range and the readout signal is updated.
Based on a same application concept, the embodiment further provides an apparatus for optimizing a parameter of a multi-qubit readout signal. Referring to
In addition, based on a same inventive concept, the embodiment further provides a quantum computer, configured to perform optimization of a parameter of a multi-qubit readout signal according to the method for optimizing a parameter of a multi-qubit readout signal, or including the apparatus for optimizing a parameter of a multi-qubit readout signal.
In conclusion, a parameter of a readout signal of a plurality of associated qubits may be optimized to ensure accuracy of measurement results, so that the plurality of associated qubits may be applied, practicality of the plurality of associated qubits is improved, and an application scenario of the plurality of associated qubits is expanded.
The foregoing description is merely a description of the preferred embodiments of the present disclosure, and is not intended to limit the scope of the present disclosure. Any change or modification made by a person of ordinary skill in the art according to the foregoing disclosure falls within the protection scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111625730.7 | Dec 2021 | CN | national |
| 202111680550.9 | Dec 2021 | CN | national |
The present disclosure is a continuation of International Application No. PCT/CN2022/140862, filed on Dec. 22, 2022, which claims the priority to Chinese Patent Application No. 202111625730.7, filed on Dec. 27, 2021 and entitled “METHOD AND APPARATUS FOR DETERMINING MEASUREMENT RESULT OF MULTIPLE QUBITS, AND QUANTUM COMPUTER”, and Chinese Patent Application No. 202111680550.9, filed on Dec. 30, 2021 and entitled “METHOD AND APPARATUS FOR OPTIMIZING PARAMETER OF READOUT SIGNAL OF MULTIPLE QUBITS, AND QUANTUM COMPUTER”. All of the aforementioned patent applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2022/140862 | Dec 2022 | WO |
| Child | 18433983 | US |
