[go: up one dir, main page]

CN109406875B - Qubit frequency calibration method based on Ramsey interference experiment - Google Patents

Qubit frequency calibration method based on Ramsey interference experiment Download PDF

Info

Publication number
CN109406875B
CN109406875B CN201811196088.3A CN201811196088A CN109406875B CN 109406875 B CN109406875 B CN 109406875B CN 201811196088 A CN201811196088 A CN 201811196088A CN 109406875 B CN109406875 B CN 109406875B
Authority
CN
China
Prior art keywords
qubit
frequency
ramsey interference
ramsey
interference experiment
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811196088.3A
Other languages
Chinese (zh)
Other versions
CN109406875A (en
Inventor
孔伟成
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Benyuan Quantum Computing Technology Hefei Co ltd
Original Assignee
Origin Quantum Computing Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Origin Quantum Computing Technology Co Ltd filed Critical Origin Quantum Computing Technology Co Ltd
Priority to CN201811196088.3A priority Critical patent/CN109406875B/en
Publication of CN109406875A publication Critical patent/CN109406875A/en
Application granted granted Critical
Publication of CN109406875B publication Critical patent/CN109406875B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

本发明属于量子测控技术领域，特别是一种基于Ramsey干涉实验进行量子比特频率校准方法，该方法包括对量子比特进行N次Ramsey干涉实验，并记录根据每次Ramsey干涉实验的结果得到的

Figure DDA0002594091430000011
其中：n＝1,2,…N，根据N个
Figure DDA0002594091430000012
和对应的
Figure DDA0002594091430000013
组成的坐标点在正交平面坐标系中进行直线拟合，获得拟合直线方程；根据所述拟合直线方程获得fq值。本发明借助Ramsey干涉实验以及数据拟合有效保证最终得到的量子比特频率校准值的精度。

Figure 201811196088

The invention belongs to the technical field of quantum measurement and control, in particular to a method for calibrating qubit frequency based on Ramsey interference experiment.

Figure DDA0002594091430000011
Where: n=1,2,...N, according to N
Figure DDA0002594091430000012
and corresponding
Figure DDA0002594091430000013
The formed coordinate points are fitted with a straight line in an orthogonal plane coordinate system to obtain a fitted straight line equation; the f q value is obtained according to the fitted straight line equation. The present invention effectively guarantees the precision of the finally obtained qubit frequency calibration value by means of Ramsey interference experiment and data fitting.

Figure 201811196088

Description

基于Ramsey干涉实验进行量子比特频率校准方法Qubit frequency calibration method based on Ramsey interference experiment

技术领域technical field

本发明属于量子测控技术领域，特别是一种基于Ramsey干涉实验进行量子比特频率校准方法。The invention belongs to the technical field of quantum measurement and control, in particular to a qubit frequency calibration method based on Ramsey interference experiment.

背景技术Background technique

量子计算在解决特定问题上具有远超经典计算机性能的发展潜力。为了实现量子计算机，需要获得一块包含有足够数量与足够质量量子比特的量子芯片，并且能够对量子比特进行极高保真度的量子逻辑门操作与读取。然而量子比特的量子比特频率参数会随环境波动，如果忽略这种波动，会导致量子逻辑门操作的保真度的下降，也会影响到读取的效率。因此，量子芯片的参数，尤其量子比特频率参数，需要定期校准，才能确保长期稳定发挥最佳性能也就是量子算法的最佳执行效果。Quantum computing has the potential to far exceed the performance of classical computers in solving specific problems. In order to realize a quantum computer, it is necessary to obtain a quantum chip that contains a sufficient number and quality of qubits, and can operate and read quantum logic gates with extremely high fidelity on the qubits. However, the qubit frequency parameter of the qubit will fluctuate with the environment. If this fluctuation is ignored, the fidelity of the quantum logic gate operation will be reduced, and the reading efficiency will also be affected. Therefore, the parameters of quantum chips, especially the qubit frequency parameters, need to be calibrated regularly to ensure long-term stability and optimal performance, that is, the best execution effect of quantum algorithms.

通常，量子比特频率的获取方法是利用能谱测量实验。量子比特能谱测量实验是指对一个量子比特施加持续的频率为fd的驱动信号使得量子比特由基态跃迁到激发态，在该驱动信号结束后对该量子比特施加读取脉冲信号以获得量子比特的激发态分布几率P1(fd)随驱动信号频率fd的变化关系。当驱动信号的频率fd与量子比特频率f0很靠近时，既可以有效地激发量子比特，使得量子比特的激发态分布P1(fd)增大。而在驱动信号频率远离量子比特真实频率时，P1(fd)趋近0。对于当前的位于4-8GHz频段的量子比特比如说超导量子比特来说，利用高性能的量子比特信号发生系统、接收系统，量子比特能谱测量实验能够将量子比特频率f0的误差控制在1MHz左右。Typically, the frequency of qubits is obtained using energy-spectroscopy experiments. Qubit energy spectrum measurement experiment refers to applying a continuous driving signal of frequency f d to a qubit to make the qubit transition from the ground state to the excited state, and applying a read pulse signal to the qubit after the end of the driving signal to obtain the quantum The relationship between the excited state distribution probability P1(f d ) of the bit and the frequency f d of the driving signal. When the frequency f d of the driving signal is very close to the frequency f 0 of the qubit, the qubit can be excited effectively, so that the excited state distribution P1(f d ) of the qubit increases. When the driving signal frequency is far from the real frequency of the qubit, P1(f d ) approaches 0. For the current qubits located in the 4-8GHz frequency band, such as superconducting qubits, using the high-performance qubit signal generating system and receiving system, the qubit energy spectrum measurement experiment can control the error of the qubit frequency f 0 within 1MHz or so.

现有的能谱测量实验获得量子比特频率f0的误差在1MHz不能满足量子比特频率精度的要求，不能实现量子比特频率的校验需求。The error of the qubit frequency f 0 obtained by the existing energy spectrum measurement experiment cannot meet the requirements of the qubit frequency accuracy at 1 MHz, and cannot meet the verification requirements of the qubit frequency.

发明内容SUMMARY OF THE INVENTION

本发明的目的是提供一种基于Ramsey干涉实验进行量子比特频率校准方法，以解决现有技术中的不足，它能够实现量子比特频率的精确校准。The purpose of the present invention is to provide a method for qubit frequency calibration based on Ramsey interference experiment, so as to solve the deficiencies in the prior art, and it can realize precise calibration of qubit frequency.

本发明采用的技术方案如下：The technical scheme adopted in the present invention is as follows:

一种基于Ramsey干涉实验进行量子比特频率校准方法，其中，包括：A method for qubit frequency calibration based on Ramsey interference experiment, comprising:

对量子比特进行N次Ramsey干涉实验，并记录根据每次Ramsey干涉实验的结果得到的

Figure GDA0002594091420000021
其中：n＝1,2,…N，
Figure GDA0002594091420000022
为第n次Ramsey干涉实验所采用的π/2量子逻辑门操作对应的微波脉冲信号的载频，
Figure GDA0002594091420000023
为第n次Ramsey干涉实验得到的量子比特的震荡频率，且
Figure GDA0002594091420000024
fq为量子比特频率,N为大于1的正整数；Perform N Ramsey interference experiments on qubits and record the results obtained from each Ramsey interference experiment
Figure GDA0002594091420000021
Where: n=1,2,...N,
Figure GDA0002594091420000022
is the carrier frequency of the microwave pulse signal corresponding to the π/2 quantum logic gate operation used in the nth Ramsey interference experiment,
Figure GDA0002594091420000023
is the oscillation frequency of the qubit obtained from the nth Ramsey interference experiment, and
Figure GDA0002594091420000024
f q is the qubit frequency, and N is a positive integer greater than 1;

根据N个

Figure GDA0002594091420000026
和对应的
Figure GDA0002594091420000025
组成的坐标点在正交平面坐标系中进行直线拟合，获得拟合直线方程；According to N
Figure GDA0002594091420000026
and corresponding
Figure GDA0002594091420000025
The formed coordinate points are fitted with a straight line in the orthogonal plane coordinate system to obtain the fitted straight line equation;

根据所述拟合直线方程获得fq值。The f q values are obtained from the fitted line equation.

如上所述的基于Ramsey干涉实验进行量子比特频率校准方法，其中，优选的是，所述第n次Ramsey干涉实验，具体包括：The above-mentioned method for qubit frequency calibration based on Ramsey interference experiment, wherein, preferably, the nth Ramsey interference experiment specifically includes:

m次对量子比特施加两个时间间隔τm的两个π/2量子逻辑门操作，并获得每次对量子比特施加两个时间间隔τm的两个π/2量子逻辑门操作后，量子比特的激发态分布几率Pfd(τm)；其中，τm为第m次对量子比特施加的两个π/2量子逻辑门操作的时间间隔，m为大于1的正整数；After applying two π/2 quantum logic gate operations with two time intervals τ m to the qubit m times, and obtaining two π/2 quantum logic gate operations with two time intervals τ m applied to the qubit each time, the quantum The excited state distribution probability of the bit P fd (τ m ); wherein, τ m is the time interval between two π/2 quantum logic gate operations applied to the qubit for the mth time, and m is a positive integer greater than 1;

根据每次测量得到的Pfd(τm)和τm进行

Figure GDA0002594091420000029
函数拟合，得到
Figure GDA0002594091420000028
其中：
Figure GDA0002594091420000027
为第n次Ramsey干涉实验所采用的π/2量子逻辑门操作对应的微波脉冲信号的载频，f0为量子比特的震荡频率，T0为量子比特的退相干时间，A和B为拟合系数。Based on P fd (τ m ) and τ m obtained from each measurement
Figure GDA0002594091420000029
function fitting, we get
Figure GDA0002594091420000028
in:
Figure GDA0002594091420000027
is the carrier frequency of the microwave pulse signal corresponding to the π/2 quantum logic gate operation used in the nth Ramsey interference experiment, f 0 is the oscillation frequency of the qubit, T 0 is the decoherence time of the qubit, A and B are the Combined coefficient.

如上所述的基于Ramsey干涉实验进行量子比特频率校准方法，其中，优选的是，对量子比特进行N次Ramsey干涉实验时，量子比特频率fq保持不变。In the above-mentioned method for qubit frequency calibration based on Ramsey interference experiment, it is preferred that the qubit frequency f q remains unchanged when the qubit is subjected to N times of Ramsey interference experiment.

与现有技术相比，本发明对量子比特进行N次Ramsey干涉实验，并记录根据每次Ramsey干涉实验的结果得到的

Figure GDA00025940914200000210
然后根据N个
Figure GDA00025940914200000211
和对应的
Figure GDA00025940914200000212
组成的坐标点在正交平面坐标系中进行直线拟合，获得拟合直线方程；根据所述拟合直线方程获得fq值。该过程中，每次的Ramsey干涉实验能够提供量子比特频率的精度，而在此基础上上，进一步利用每次的Ramsey干涉实验的结果进行数据拟合来减小实验误差，有效保证最终得到的量子比特频率校准值。Compared with the prior art, the present invention performs N times Ramsey interference experiments on qubits, and records the results obtained according to the results of each Ramsey interference experiment.
Figure GDA00025940914200000210
Then according to N
Figure GDA00025940914200000211
and corresponding
Figure GDA00025940914200000212
The formed coordinate points are fitted with a straight line in an orthogonal plane coordinate system to obtain a fitted straight line equation; the f q value is obtained according to the fitted straight line equation. In this process, each Ramsey interference experiment can provide the accuracy of the qubit frequency, and on this basis, the results of each Ramsey interference experiment are further used to perform data fitting to reduce the experimental error and effectively ensure the final result. Qubit frequency calibration value.

附图说明Description of drawings

图1是本发明实施例提供的基于Ramsey干涉实验进行量子比特频率校准方法的流程图。FIG. 1 is a flowchart of a method for qubit frequency calibration based on a Ramsey interference experiment provided by an embodiment of the present invention.

具体实施方式Detailed ways

下面通过参考附图描述的实施例是示例性的，仅用于解释本发明，而不能解释为对本发明的限制。The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but not to be construed as a limitation of the present invention.

Ramsey干涉实验是指对一个量子比特，施加两个π/2量子逻辑门操作，两个操作的时间间隔为τ，同时在第二个π/2量子逻辑门操作后对该量子比特施加读取脉冲以获得量子比特的激发态分布P1(τ)，并且改变时间间隔τ以获得P1(τ)的过程。The Ramsey interference experiment refers to applying two π/2 quantum logic gate operations to a qubit, and the time interval between the two operations is τ, and at the same time, the qubit is read after the second π/2 quantum logic gate operation. The process of pulsing to obtain the excited state distribution P1(τ) of the qubit, and changing the time interval τ to obtain P1(τ).

典型的Ramsey干涉实验的结果是P1(τ)是随时间间隔τ满足指数振荡衰减的数学模型如下：The result of a typical Ramsey interference experiment is that P1(τ) is a mathematical model that satisfies exponential oscillation decay with time interval τ as follows:

Figure GDA0002594091420000031
Figure GDA0002594091420000031

在上式中，A和B为拟合系数，T0为量子比特的退相干时间，fd为π/2量子逻辑门操作对应的微波脉冲信号的载频，f0为量子比特的震荡频率，且f0与该量子比特的真实频率fq、π/2量子逻辑门操作的载频频率fd满足：In the above formula, A and B are the fitting coefficients, T 0 is the decoherence time of the qubit, f d is the carrier frequency of the microwave pulse signal corresponding to the operation of the π/2 quantum logic gate, and f 0 is the oscillation frequency of the qubit , and f 0 and the real frequency f q of the qubit, and the carrier frequency f d of the π/2 quantum logic gate operation satisfy:

f0(fd)＝|fq-fd|f 0 (f d )=|f q -f d |

综上我们得到了另一个重要的结论：Ramsey干涉实验的结果，也就是P1(τ)曲线的振荡频率等于量子逻辑门操作的载频频率以及量子比特真实频率的差值，因而Ramsey干涉实验除了能够用于获得量子比特的退相干时间以外，还能同时精确获得量子比特的真实频率。To sum up, we have obtained another important conclusion: the result of the Ramsey interference experiment, that is, the oscillation frequency of the P 1 (τ) curve is equal to the difference between the carrier frequency of the quantum logic gate operation and the real frequency of the qubit, so the Ramsey interference experiment In addition to the decoherence time that can be used to obtain the qubit, the true frequency of the qubit can also be accurately obtained at the same time.

但是依然不能直接用Ramsey干涉实验来实现量子比特频率的校准。这是因为事实上Ramsey实验得到的P1(τ)需要通过数学拟合才能得到指数振荡衰减的数学模型表达式，而数学拟合的精度取决于P1(τ)原始数据的精度，因而拟合得到的振荡频率f0往往也是不准的。为了解决这个问题，并同时利用Ramsey干涉实验来实现对量子比特频率的校准，本申请的实施例提供了一种基于Ramsey干涉实验进行量子比特频率校准方法，其中，该校准方法包括如下步骤：However, it is still not possible to directly use the Ramsey interference experiment to achieve the calibration of the qubit frequency. This is because in fact the P 1 (τ) obtained by Ramsey's experiment needs to be mathematically fitted to obtain the mathematical model expression of exponential oscillation decay, and the accuracy of the mathematical fitting depends on the accuracy of the original data of P 1 (τ). The resulting oscillation frequency f 0 is often inaccurate. In order to solve this problem and use Ramsey interference experiment to calibrate the qubit frequency at the same time, the embodiment of the present application provides a method for qubit frequency calibration based on Ramsey interference experiment, wherein the calibration method includes the following steps:

步骤S1：Step S1:

对量子比特进行N次Ramsey干涉实验，并记录根据每次Ramsey干涉实验的结果得到的

Figure GDA0002594091420000044
n＝1,2,…N，
Figure GDA0002594091420000043
为第n次Ramsey干涉实验所采用的π/2量子逻辑门操作对应的微波脉冲信号的载频，
Figure GDA0002594091420000045
为每次Ramsey干涉实验得到的量子比特的震荡频率，且
Figure GDA0002594091420000041
fq为量子比特频率,N为大于1的正整数；Perform N Ramsey interference experiments on qubits and record the results obtained from each Ramsey interference experiment
Figure GDA0002594091420000044
n=1,2,...N,
Figure GDA0002594091420000043
is the carrier frequency of the microwave pulse signal corresponding to the π/2 quantum logic gate operation used in the nth Ramsey interference experiment,
Figure GDA0002594091420000045
is the oscillation frequency of the qubit obtained from each Ramsey interference experiment, and
Figure GDA0002594091420000041
f q is the qubit frequency, and N is a positive integer greater than 1;

步骤S2：根据N个

Figure GDA0002594091420000046
和对应的
Figure GDA0002594091420000047
组成的坐标点在正交平面坐标系中进行直线拟合，获得拟合直线方程；Step S2: According to N
Figure GDA0002594091420000046
and corresponding
Figure GDA0002594091420000047
The formed coordinate points are fitted with a straight line in the orthogonal plane coordinate system to obtain the fitted straight line equation;

步骤S3：Step S3:

根据所述拟合直线方程获得fq值。The f q values are obtained from the fitted line equation.

本实施通过步骤S1至步骤S3,对量子比特进行N次Ramsey干涉实验，并记录根据每次Ramsey干涉实验的结果得到的

Figure GDA0002594091420000048
然后根据N个
Figure GDA0002594091420000049
和对应的
Figure GDA0002594091420000042
组成的坐标点在正交平面坐标系中进行直线拟合，获得拟合直线方程；根据所述拟合直线方程获得fq值。该过程中，每次的Ramsey干涉实验能够提供量子比特频率的精度，而在此基础上上，进一步利用每次的Ramsey干涉实验的结果进行数据拟合来减小实验误差，整个过程借助Ramsey干涉实验以及数据拟合有效保证最终得到的量子比特频率校准值的精度。In this implementation, through steps S1 to S3, N times Ramsey interference experiments are performed on qubits, and the results obtained according to the results of each Ramsey interference experiment are recorded.
Figure GDA0002594091420000048
Then according to N
Figure GDA0002594091420000049
and corresponding
Figure GDA0002594091420000042
The formed coordinate points are fitted with a straight line in an orthogonal plane coordinate system to obtain a fitted straight line equation; the f q value is obtained according to the fitted straight line equation. In this process, each Ramsey interference experiment can provide the accuracy of the qubit frequency, and on this basis, the results of each Ramsey interference experiment are further used to perform data fitting to reduce the experimental error. The whole process uses Ramsey interference. Experiments and data fitting effectively ensure the accuracy of the final qubit frequency calibration value.

作为本实施例的优选技术方案，所述第n次Ramsey干涉实验，具体包括：As a preferred technical solution of this embodiment, the nth Ramsey interference experiment specifically includes:

(1)m次对量子比特施加两个时间间隔τm的两个π/2量子逻辑门操作，并获得每次对量子比特施加两个时间间隔τm的两个π/2量子逻辑门操作后，量子比特的激发态分布几率Pfd(τm)；其中，τm为第m次对量子比特施加的两个π/2量子逻辑门操作的时间间隔，m为大于1的正整数；(1) Applying two π/2 quantum logic gate operations with two time intervals τ m to qubits m times, and obtaining two π/2 quantum logic gate operations applying two time intervals τ m to qubits each time Then, the excited state distribution probability of the qubit P fd (τ m ); wherein, τ m is the time interval between two π/2 quantum logic gate operations applied to the qubit for the mth time, and m is a positive integer greater than 1;

(2)根据每次测量得到的Pfd(τm)和τm进行

Figure GDA00025940914200000410
函数拟合，得到
Figure GDA00025940914200000411
其中：
Figure GDA00025940914200000412
为第n次Ramsey干涉实验所采用的π/2量子逻辑门操作对应的微波脉冲信号的载频，f0为量子比特的震荡频率，T0为量子比特的退相干时间，A和B为拟合系数。(2) According to P fd (τ m ) and τ m obtained by each measurement
Figure GDA00025940914200000410
function fitting, we get
Figure GDA00025940914200000411
in:
Figure GDA00025940914200000412
is the carrier frequency of the microwave pulse signal corresponding to the π/2 quantum logic gate operation used in the nth Ramsey interference experiment, f 0 is the oscillation frequency of the qubit, T 0 is the decoherence time of the qubit, A and B are the Combined coefficient.

下面将结合具体实施过程介绍本实施例，具体的：The present embodiment will be introduced below in conjunction with the specific implementation process, specifically:

对量子比特实施一系列的Ramsey干涉实验，即以上实施例的N次，每次改变量子逻辑门操作的载频频率fd(即每次采用的量子逻辑门操作的载频频率为

Figure GDA0002594091420000051
)，从而得到多条P1(τ)曲线，从每条曲线中，均可通过拟合的方法得到振荡频率f0(fd)(即
Figure GDA0002594091420000052
)。很显然，由于在系列Ramsey干涉实验的期间(通常不超过1小时)，量子比特真实频率可以认为精确不变，则Ramsey干涉实验所得到的振荡频率f0(即
Figure GDA0002594091420000053
)必然是随量子逻辑门操作的载频频率fd变化的，而且变化关系式就是:f0(fd)＝|fq-fd|A series of Ramsey interference experiments are carried out on the quantum bits, that is, N times in the above embodiment, each time the carrier frequency f d of the quantum logic gate operation is changed (that is, the carrier frequency of the quantum logic gate operation adopted each time is
Figure GDA0002594091420000051
), thereby obtaining multiple P 1 (τ) curves, from each curve, the oscillation frequency f 0 (f d ) can be obtained by fitting method (ie
Figure GDA0002594091420000052
). Obviously, since the real frequency of the qubit can be considered to be exactly constant during the period of the series of Ramsey interference experiments (usually not more than 1 hour), the oscillation frequency f 0 obtained by the Ramsey interference experiment (that is,
Figure GDA0002594091420000053
) must change with the carrier frequency f d of the quantum logic gate operation, and the change relationship is: f 0 (f d )=|f q -f d |

即：

Figure GDA0002594091420000054
which is:
Figure GDA0002594091420000054

因此，通过多次Ramsey干涉实验得到的f0(fd)曲线，再利用上述表达式进行拟合，就能够精确地获得量子比特的真实频率fq。利用Ramsey干涉实验拟合得到f0、改变fd重复进行Ramsey干涉得到f0(fd)(即

Figure GDA0002594091420000055
)并再次拟合得到fq的方法，能够将量子比特真实频率的精度提高至10kHz的水平，充分满足了我们对于精准量子比特真实频率的需要。而进一步提高量子比特真实频率的精度，依赖于整个系统的整体提升，以获得噪声更小的P1(τ)曲线。Therefore, the f 0 (f d ) curve obtained by multiple Ramsey interference experiments can be fitted with the above expression, and the real frequency f q of the qubit can be accurately obtained. Use Ramsey interference experiment to get f 0 , and change f d to repeat Ramsey interference to obtain f 0 (f d ) (ie
Figure GDA0002594091420000055
) and fitting again to obtain f q , which can improve the accuracy of the real frequency of qubits to the level of 10kHz, which fully meets our needs for accurate real frequencies of qubits. To further improve the accuracy of the real frequency of qubits, it depends on the overall improvement of the entire system to obtain a P 1 (τ) curve with less noise.

以上方法适用于量子比特真实频率在系列Ramsey干涉实验的期间(通常不超过1小时)几乎不变的所有情况，尤其是适用于量子比特真实频率可能存在缓慢时间漂移的情况下(比如1天1MHz)。以上方法能够有效地实现定期对量子比特真实频率的重新校准。The above method is suitable for all cases where the real frequency of the qubit is almost constant during the period of a series of Ramsey interference experiments (usually no more than 1 hour), especially for the case where the real frequency of the qubit may have a slow time drift (such as 1MHz for 1 day) ). The above method can effectively achieve periodic recalibration of the true frequency of the qubit.

以上依据图式所示的实施例详细说明了本发明的构造、特征及作用效果，以上所述仅为本发明的较佳实施例，但本发明不以图面所示限定实施范围，凡是依照本发明的构想所作的改变，或修改为等同变化的等效实施例，仍未超出说明书与图示所涵盖的精神时，均应在本发明的保护范围内。The structure, features and effects of the present invention have been described in detail above according to the embodiments shown in the drawings. The above are only the preferred embodiments of the present invention, but the scope of the present invention is not limited by the drawings. Changes made to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, shall fall within the protection scope of the present invention as long as they do not exceed the spirit covered by the description and drawings.

Claims (2)

1. A method for carrying out quantum bit frequency calibration based on Ramsey interference experiments is characterized by comprising the following steps:
performing Ramsey interference experiments on the quantum bits for N times, and recording the Ramsey interference experiments obtained according to the result of each Ramsey interference experiment
Figure FDA0002594091410000011
Wherein: n is 1,2, … N; wherein:
Figure FDA0002594091410000012
the carrier frequency of the microwave pulse signal corresponding to the pi/2 quantum logic gate operation adopted by the nth Ramsey interference experiment,
Figure FDA0002594091410000013
the oscillation frequency of the quantum bit obtained from the nth Ramsey interference experiment, and
Figure FDA0002594091410000014
fqis the qubit frequency, N being a positive integer greater than 1;
according to N number of
Figure FDA0002594091410000015
And corresponding
Figure FDA0002594091410000016
Performing linear fitting on the formed coordinate points in an orthogonal plane coordinate system to obtain a fitted linear equation;
obtaining f according to the fitted linear equationqThe value is obtained.
2. The method for performing quantum bit frequency calibration based on Ramsey interference experiments according to claim 1, wherein the nth Ramsey interference experiment specifically comprises:
applying two time intervals tau to qubits m timesmAnd obtaining two time intervals tau each time the qubit is appliedmAfter the two pi/2 quantum logic gates are operated, the probability P of the distribution of the excited state of the qubitfd(τm) (ii) a Wherein, taumA time interval for two pi/2 quantum logic gate operations applied to the qubit for the mth time, m being a positive integer greater than 1;
from P obtained for each measurementfd(τm) And τmTo carry out
Figure FDA0002594091410000017
Fitting a function to obtain
Figure FDA0002594091410000018
Wherein:
Figure FDA0002594091410000019
carrier frequency f of microwave pulse signal corresponding to pi/2 quantum logic gate operation adopted by nth Ramsey interference experiment0For oscillating frequency of qubits, T0And A and B are fitting coefficients.
CN201811196088.3A 2018-10-15 2018-10-15 Qubit frequency calibration method based on Ramsey interference experiment Active CN109406875B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811196088.3A CN109406875B (en) 2018-10-15 2018-10-15 Qubit frequency calibration method based on Ramsey interference experiment

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811196088.3A CN109406875B (en) 2018-10-15 2018-10-15 Qubit frequency calibration method based on Ramsey interference experiment

Publications (2)

Publication Number Publication Date
CN109406875A CN109406875A (en) 2019-03-01
CN109406875B true CN109406875B (en) 2020-09-15

Family

ID=65467949

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811196088.3A Active CN109406875B (en) 2018-10-15 2018-10-15 Qubit frequency calibration method based on Ramsey interference experiment

Country Status (1)

Country Link
CN (1) CN109406875B (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111722084B (en) * 2020-06-29 2021-07-20 浪潮集团有限公司 A method for automatic calibration of parameters of a superconducting quantum chip and related components
CN114594306B (en) * 2020-12-07 2024-04-05 本源量子计算科技（合肥）股份有限公司 Method and device for calibrating superconducting qubit frequency and readable storage medium
CN115700385B (en) * 2021-07-28 2024-06-14 本源量子计算科技（合肥）股份有限公司 Method for obtaining DC crosstalk coefficient and DC crosstalk matrix between quantum bits
CN115700613B (en) * 2021-07-28 2024-04-05 本源量子计算科技（合肥）股份有限公司 Quantum bit control signal optimization method and device and quantum computer
CN117196046A (en) * 2022-05-30 2023-12-08 本源量子计算科技（合肥）股份有限公司 Testing methods and quantum control systems for qubit phase relaxation time parameters
CN115713124A (en) * 2022-11-30 2023-02-24 阿里巴巴达摩院(杭州)科技有限公司 Method for determining decoherence model of qubit and computer-readable storage medium
CN118759252A (en) * 2024-06-12 2024-10-11 华南师范大学 A quantum frequency calibration method and system based on composite pulse sequence

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101246378A (en) * 2007-02-14 2008-08-20 株式会社东芝 Quantum computers and quantum computing methods
CN205139243U (en) * 2015-09-25 2016-04-06 南京大学 Adjustable transmon quantum bit system based on coalesced copper rectangular cavity
EP3300004A1 (en) * 2016-09-27 2018-03-28 Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO Method for executing a quantum error correction cycle in a quantum computer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101246378A (en) * 2007-02-14 2008-08-20 株式会社东芝 Quantum computers and quantum computing methods
CN205139243U (en) * 2015-09-25 2016-04-06 南京大学 Adjustable transmon quantum bit system based on coalesced copper rectangular cavity
EP3300004A1 (en) * 2016-09-27 2018-03-28 Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO Method for executing a quantum error correction cycle in a quantum computer

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
量子模拟及量子算法在超导量子系统中的应用;戴坤哲;《中国博士学位论文全文数据库基础科学辑》;20180915;全文 *

Also Published As

Publication number Publication date
CN109406875A (en) 2019-03-01

Similar Documents

Publication Publication Date Title
CN109406875B (en) Qubit frequency calibration method based on Ramsey interference experiment
JP7223174B2 (en) Hybrid Quantum-Classical Computer for Bayesian Inference with Engineering Likelihood Function for Robust Amplitude Estimation
Abrams et al. Implementation of XY entangling gates with a single calibrated pulse
US10839306B2 (en) Hardware-efficient variational quantum eigenvalue solver for quantum computing machines
Córcoles et al. Demonstration of a quantum error detection code using a square lattice of four superconducting qubits
Vepsäläinen et al. Improving qubit coherence using closed-loop feedback
US9946973B2 (en) Long-time low-latency quantum memory by dynamical decoupling
US10552755B2 (en) Systems and methods for improving the performance of a quantum processor to reduce intrinsic/control errors
US20220374750A1 (en) Bayesian quantum circuit fidelity estimation
US12499379B2 (en) Readout-error mitigation for quantum expectation
EP4257990A1 (en) Method and device for calibrating frequency of superconducting qubit, and readable storage medium
CN114096970A (en) Measurement of Quantum State purity
US20220261679A1 (en) Probe of qubit-resonator dispersive shift using ac stark shift
WO2023143457A1 (en) Method and apparatus for determining high-energy-state regulation and control signal of quantum bit, and quantum computer
CN117769712A (en) Benchmarking protocol for quantum gates
CN111612151B (en) A control method, system and related components of a quantum computer
CN113177641A (en) Feedback optimization method of quantum bit control pulse
Kudra et al. Experimental realization of deterministic and selective photon addition in a bosonic mode assisted by an ancillary qubit
Vora et al. Ml-powered fpga-based real-time quantum state discrimination enabling mid-circuit measurements
CN117693759A (en) Quantum bit gate implementation using phase-shifted microwave pulses
US11687818B2 (en) Hardware-efficient calibration framework for quantum computing devices
Dasgupta et al. Improving probabilistic error cancellation in the presence of nonstationary noise
Konev et al. Sequential fixed accuracy estimation for nonstationary autoregressive processes
CN115423110B (en) Quantum state reading and determining method and system for quantum bits and quantum computer
CN117813613A (en) Decomposition of a two-qubit gate

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CP03 Change of name, title or address

Address after: 230088 6th floor, E2 building, phase II, innovation industrial park, 2800 innovation Avenue, high tech Zone, Hefei City, Anhui Province

Patentee after: Benyuan Quantum Computing Technology (Hefei) Co.,Ltd.

Country or region after: China

Address before: 230088 6th floor, E2 building, phase II, innovation industrial park, 2800 innovation Avenue, high tech Zone, Hefei City, Anhui Province

Patentee before: ORIGIN QUANTUM COMPUTING COMPANY, LIMITED, HEFEI

Country or region before: China

CP03 Change of name, title or address
CP03 Change of name, title or address

Address after: 230088 Anhui Province, Hefei City, Gaoxin District, Chengxiqiao Community Service Center, No. 900 Wangjiang West Road, Zhong'an Chuanggu Science and Technology Park Phase I, Building D8

Patentee after: Benyuan Quantum Computing Technology (Hefei) Co.,Ltd.

Country or region after: China

Address before: 230088 6th floor, E2 building, phase II, innovation industrial park, 2800 innovation Avenue, high tech Zone, Hefei City, Anhui Province

Patentee before: Benyuan Quantum Computing Technology (Hefei) Co.,Ltd.

Country or region before: China

CP03 Change of name, title or address