Quantum measurement and control signal feedback device and method based on weak magnetic detection

Abstract

The invention discloses a quantum measurement and control signal feedback device based on weak magnetic detection and a method thereof. The quantum measurement and control signal feedback device comprises a quantum chip, a superconducting quantum interferometer detector, a control signal generation module and a main control module. A first control signal is generated through a control signal generation module to control quantum bits, the state change of the quantum bits generates a stray magnetic field, and the stray magnetic field is captured by a superconducting quantum interferometer detector and converted into a weak magnetic signal. And the main control module receives the weak magnetic signal, compares the weak magnetic signal with the first control signal, generates a feedback control signal, adjusts the state of the quantum bits, measures signal crosstalk between the quantum bits by setting the size and position of the probe, and improves the control precision. According to the invention, the superconducting quantum interferometer detector monitors the stray magnetic field generated by the quantum bits to realize real-time feedback, the state of the quantum bits does not need to be directly read, the interference to the operation of the quantum chip is minimum, the control precision of the quantum chip is remarkably improved, and meanwhile, the signal crosstalk between the quantum bits can be detected.

Description

Technical Field

[0001] The present invention relates to the field of quantum information technology, and in particular to a quantum measurement and control signal feedback device based on weak magnetic field detection and a method thereof. Background Art

[0002] With the rapid development of quantum information technology, quantum chips and quantum bit control technology have become hot topics in the research field. As the core component of quantum information processing, quantum chips usually need to work in extremely low temperature environments to ensure high-precision control signals and feedback control. Traditional quantum chip control methods mainly rely on reading the logical state of quantum bits to achieve feedback control, but this method has deficiencies in real-time and anti-interference capabilities, which may cause delays and instability in feedback control, thereby affecting the overall performance of quantum chips.

[0003] To overcome these challenges, researchers began to use superconducting quantum interference devices for feedback control of weak magnetic field detection. As a highly sensitive magnetic field detector, the superconducting quantum interference device can operate reliably in extremely low temperature environments and sense the weak stray magnetic field generated by the quantum bit control signal. However, although the weak magnetic field detection method based on superconducting quantum interference devices has many advantages in theory, a series of technical problems still need to be solved in practical applications. For example, patent CN114037085A is a quantum manipulation feedback system and method. The feedback system needs to characterize the quantum state, and there are problems such as insufficient real-time performance, susceptibility to interference, and inability to detect signal crosstalk.

[0004] Therefore, how to solve the deficiencies and shortcomings of existing technologies through effective quantum measurement and control signal feedback methods has become an important issue that researchers in this field need to solve urgently. Summary of the invention

[0005] The purpose of the present invention is to address the above-mentioned problems and to provide a quantum measurement and control signal feedback device based on weak magnetic field detection and a method thereof.

[0006] The technical solution of the present invention is: a quantum chip, the quantum chip includes an input end and an output end, and a plurality of signal transmission lines connected between the input end and the output end, the signal transmission line includes a first signal node, a quantum bit is connected between the first signal node and the output end, and the input end is used to receive a control signal; a control signal generation module is used to generate a first control signal for controlling the quantum bit in the quantum chip, the first control signal is transmitted in the plurality of signal transmission lines and generates a stray magnetic field; a superconducting quantum interferometer detector is used to detect a weak magnetic signal generated by the stray magnetic field at the first signal node; a main control module is used to compare the first control signal with the weak magnetic signal and generate a feedback control signal, and the feedback control signal is used to adjust the weak magnetic signal to be consistent with the first control signal.

[0007] As an improvement of the embodiment of the present invention, the superconducting quantum interference device detector is provided with a probe, and the projection area of ​​the probe is less than 0.1mm 2 , the distance between the probe and the quantum chip is N, 0.1 mm <N<5mm。

[0008] As an improvement of the embodiment of the present invention, the distance N between the probe and the quantum chip is 1 mm.

[0009] As an improvement to an embodiment of the present invention, the feedback control signal inverts the difference between the first control signal and the weak magnetic signal, and is transmitted to the first signal node through a feedback loop to compensate for the fluctuation of the first control signal, so that the weak magnetic signal is consistent with the first control signal.

[0010] As an improvement of an embodiment of the present invention, the quantum chip includes a plurality of quantum gates for performing logical operations or quantum operations on quantum bits. The quantum gates operate based on the logical states of the quantum bits to achieve processing and transformation of quantum information.

[0011] As an improvement of an embodiment of the present invention, the main control module further includes a signal amplification unit, and the signal amplification unit is used to amplify the weak magnetic signal detected by the superconducting quantum interference device detector.

[0012] As an improvement of an embodiment of the present invention, the main control module further includes a signal filtering unit, and the signal filtering unit is used to filter the weak magnetic signal detected by the superconducting quantum interference device detector.

[0013] As an improvement of the embodiment of the present invention, the main control module further includes a comparator, and the comparator is used to compare the difference between the weak magnetic signal and the first control signal.

[0014] To achieve one of the above-mentioned purposes of the invention, an embodiment of the present invention provides a quantum measurement and control signal feedback method based on weak magnetic field detection. The quantum measurement and control signal feedback method is applied to a quantum measurement and control signal feedback device as described in any one of the above items, and comprises the following steps: generating a first control signal for controlling a quantum bit in a quantum chip by the control signal generation module and transmitting the signal to the input end of the quantum chip; the first control signal is transmitted in the plurality of signal transmission lines and generates a stray magnetic field; the weak magnetic signal generated by the stray magnetic field at the first signal node is detected by the superconducting quantum interference device detector; the main control module compares the weak magnetic signal with the first control signal and generates a feedback control signal, and the feedback control signal is used to adjust the weak magnetic signal to be consistent with the first control signal.

[0015] As an improvement of the embodiment of the present invention, the following steps are also included: measuring the signal crosstalk between the quantum bits by a probe arranged in the superconducting quantum interference device detector and feeding back the signal crosstalk to the main control module.

[0016] A quantum measurement and control signal feedback method based on weak magnetic detection and a device thereof provided by an embodiment of the present invention have the following advantages: the present invention realizes real-time feedback control by real-time monitoring of the stray magnetic field generated by the quantum bit control signal through a superconducting quantum interferometer, does not need to directly read the quantum bit state, and causes minimal interference to the operation of the quantum chip, significantly improves the control accuracy and stability of the quantum chip, and can detect signal crosstalk between quantum bits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the positions of the quantum chip and the superconducting quantum interference device detector of the present invention; Figure 2 It is a flow chart of the quantum measurement and control signal feedback method based on weak magnetic field detection described in the present invention. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0019] If the present invention involves directions (for example, up, down, left, right, front, back, outside, inside, etc.) when describing, the directions involved need to be defined.

[0020] The scope of the embodiments herein includes the entire scope of the claims, and all available equivalents of the claims.Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements.In fact, the first element can also be called the second element, and vice versa.Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements not only include those elements, but also include other elements not clearly listed, or also include elements inherent to such structure, device or equipment.In the absence of more restrictions, the elements limited by the statement "include one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements.Each embodiment herein is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same similar parts between each embodiment can be referred to each other.

[0021] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0022] Embodiment 1 of the present invention provides a quantum measurement and control signal feedback device based on weak magnetic field detection, including: Quantum chip 1, such as Figure 1 As shown, the quantum chip 1 includes an input terminal 11 and an output terminal 12, and a plurality of signal transmission lines 13 connected between the input terminal 11 and the output terminal 12. The signal transmission line 13 includes a first signal node 14. A quantum bit 15 is connected between the first signal node 14 and the output terminal 12. The input terminal 11 is used to receive a control signal. In practice, a quantum chip is a core component in the field of quantum information technology. Its basic unit is a quantum bit. The logical state of a quantum bit can be 0, 1, and a superposition state of 0 and 1. The state of a quantum bit can be manipulated by an external control signal.

[0023] The control signal generation module is used to generate a first control signal for controlling the quantum bit 15 in the quantum chip 1, wherein the first control signal is transmitted in the plurality of signal transmission lines 13 and generates a stray magnetic field; in practice, the first control signal may be an electrical signal or a microwave signal, etc. When the quantum bit 15 receives the first control signal, its logic state changes.

[0024] The superconducting quantum interference device detector 2 is used to detect the weak magnetic signal generated by the stray magnetic field at the first signal node 14; here, the superconducting quantum interference device detector 2 is a highly sensitive magnetic field detector that can detect weak magnetic field changes in an extremely low temperature environment. The superconducting quantum interference device detector 2 described in the present invention is used to detect the stray magnetic field at the first signal node 14, and convert the detected weak magnetic signal into an electrical signal output.

[0025] The main control module is used to compare the first control signal with the field-weakening signal and generate a feedback control signal, which is used to adjust the field-weakening signal to be consistent with the first control signal.

[0026] Here, before the device starts, initialization operations need to be performed, including setting the working parameters of the quantum chip 1, calibrating the sensitivity of the superconducting quantum interference device detector 2, and configuring the control logic of the main control module, etc. The control signal generation module generates the first control signal according to a preset algorithm or instruction, and transmits the first control signal to the quantum chip 1 to manipulate the state of the quantum bit 15. The first control signal is transmitted in the plurality of signal transmission lines 13 and generates a stray magnetic field. The superconducting quantum interference device detector 2 outputs the detected magnetic field signal as an electrical signal to the main control module by induction. The main control module receives the first control signal and the field-weakening signal output by the superconducting quantum interference device detector 2, and compares and analyzes the first control signal with the field-weakening signal. If there is a difference between the first control signal and the field-weakening signal, the main control module generates a corresponding feedback control signal, and adjusts the fluctuation of the first control signal based on the feedback control signal, thereby improving the accuracy of the control of the quantum chip 1. At the same time, the main control module can also detect the signal crosstalk between the quantum bits 15 on the quantum chip 1 in real time, and adjust the position and size of the probe 21 in the superconducting quantum interference device detector 2 according to the detection result to optimize the detection effect.

[0027] In this embodiment, a probe 21 is provided in the superconducting quantum interference device detector 2, and the projected area of the probe 21 is less than 0.1 mm 2 , and the distance between the probe 21 and the quantum chip 1 is N, 0.1 mm < N < 5 mm. Preferably, N = 1 mm. It can be understood that setting N to 1 mm can not only maintain an appropriate interval between the probe 21 and the quantum chip 1, reduce the physical contact between the probe 21 and the quantum chip 1, thereby reducing the noise and interference generated by the contact, but also ensure that the superconducting quantum interference device detector 2 can capture the magnetic field signal, improving the accuracy and reliability of the measurement.

[0028] In this embodiment, the feedback control signal inverts the difference between the first control signal and the field-weakening signal, and conducts it through the feedback loop to the first signal node 14 to compensate for the fluctuation of the first control signal, so that the field-weakening signal is consistent with the first control signal.

[0029] Here, the main control module is also provided with a feedback loop connecting the main control module and the quantum chip 1, and the feedback loop is used to conduct the feedback control signal to the first signal node 14. In practice, the state of the quantum bit 15 in the quantum chip 1 needs to be regulated by a control signal. However. Due to factors such as environmental noise and system instability, the first control signal directly applied often fluctuates, which affects the stability and accuracy of the state of the quantum bit 15. The feedback control signal is generated based on the difference between the first control signal and the weak magnetic signal detected by the superconducting quantum interference device detector 2 at the first signal node 14, and this difference reflects the deviation of the first control signal relative to the weak magnetic signal. In order to eliminate this deviation, a feedback control signal that is inversely proportional to the difference is generated. The function of the feedback control signal is to fine-tune the weak magnetic signal through a feedback loop to compensate for the fluctuation of the first control signal. It can be understood that this achieves precise control of the state of the quantum bit 15 and high-stability operation of the quantum chip 1.

[0030] In this embodiment, the quantum chip 1 includes a plurality of quantum gates for performing logical operations or quantum operations on the quantum bits 15. The quantum gates operate based on the logical states of the quantum bits 15 to achieve processing and transformation of quantum information.

[0031] In practice, quantum gates can be single-qubit 15 gates, such as Hadamardgate, Pauli-Xgate (NOT gate), Phasegate, etc.; dual-qubit 15 gates: such as Controlled-NOTgate (CNOT gate), Controlled-Zgate, etc.; multi-qubit 15 gates: such as Toffoligate, Fredkingate, etc. It can be understood that quantum gates operate based on the logical state of qubits 15 and play a vital role in quantum information processing.

[0032] In this embodiment, the main control module further includes a signal amplifying unit, and the signal amplifying unit is used to amplify the weak magnetic signal detected by the superconducting quantum interference device detector 2.

[0033] Here, the main task of the signal amplification unit is to amplify the weak electrical signal output by the superconducting quantum interference device detector 2 so that subsequent signal processing can be carried out accurately and effectively. In order to reduce noise interference during the amplification process, the signal amplification unit can use a low-noise amplifier to ensure that the noise generated by itself is minimized while amplifying the signal. Since the superconducting quantum interference device detector 2 may generate signals of different amplitudes in different application scenarios, the signal amplification unit described in this embodiment has an adjustable gain function, allowing the user to adjust the amplification factor according to actual needs, thereby achieving the best signal quality. In order to maintain the integrity of the signal, the signal amplification unit also has high linearity, that is, a good linear relationship should be maintained between the input signal and the second signal. It can be understood that this helps to reduce distortion and avoid errors caused by nonlinear effects. In addition, in order to reduce the influence of electromagnetic interference and radio frequency interference, the signal amplification unit and its peripheral circuits adopt shielding measures to ensure the purity of the signal. The main control module effectively solves the problem of the weak second signal of the superconducting quantum interference device detector 2 by integrating the signal amplification unit, and improves the sensitivity and accuracy of the entire system.

[0034] In this embodiment, the main control module further includes a signal filtering unit, and the signal filtering unit is used to filter the weak magnetic signal detected by the superconducting quantum interference device detector 2.

[0035] In practice, since the signal received by the main control module is usually accompanied by various noises and interferences, direct processing may cause inaccurate signals. Therefore, the main control module in this embodiment introduces a signal filtering unit to filter the received first control signal and weak magnetic signal, thereby improving the signal-to-noise ratio and overall quality of the signal. According to application requirements and signal characteristics, the signal filtering unit can use different types of filters, such as low-pass filters, high-pass filters, band-pass filters or band-stop filters. Different filters can remove noise above or below a specific frequency, or only allow signals within a specific frequency range to pass. In order to improve the adaptability and flexibility of the filter, the signal filtering unit can also use adaptive filtering technology. It can be understood that the adaptive filtering technology can automatically adjust the parameters of the filter according to the changes in the input signal, thereby achieving effective suppression of different types of noise. In order to verify the effect of the filtering unit, it is necessary to evaluate the quality of the signal before and after filtering, and the improvement degree of the signal quality by the filtering unit can be objectively reflected by calculating indicators such as signal-to-noise ratio, mean square error, and peak signal-to-noise ratio.

[0036] In this embodiment, the main control module further includes a comparator, and the comparator is used to compare the difference between the weak magnetic signal and the first control signal.

[0037] Here, the comparator integrates a high-precision difference calculation circuit, which can calculate the difference between the weak magnetic signal and the first control signal in real time, and can judge whether there is a deviation in the weak magnetic signal by the calculated difference, so as to take corresponding correction measures. It can be understood that the main control module in this embodiment realizes the function of comparing the difference between the weak magnetic signal and the first control signal by integrating the comparator, which effectively improves the accuracy of the signal feedback.

[0038] Embodiment 2 of the present invention provides a quantum measurement and control signal feedback method based on weak magnetic field detection, wherein the quantum measurement and control signal feedback method is applied to the quantum measurement and control signal feedback device as described in any one of the above items, such as Figure 2 As shown, the following steps are included: Step 101, generating a first control signal for controlling a quantum bit 15 in a quantum chip 1 through the control signal generating module and transmitting the control signal to an input terminal 11 of the quantum chip 1; Step 102: The first control signal is transmitted in the plurality of signal transmission lines and generates a stray magnetic field; Step 103: Detecting a weak magnetic signal generated by a stray magnetic field at the first signal node 14 by using the superconducting quantum interference instrument; Step 104: the main control module compares the weak magnetic signal with the first control signal and generates a feedback control signal, wherein the feedback control signal is used to adjust the weak magnetic signal to be consistent with the first control signal.

[0039] In this embodiment, the following steps are also included: the signal crosstalk between the quantum bits 15 is measured by a probe 21 arranged in the superconducting quantum interference device detector 2 and fed back to the main control module.

[0040] Here, in the quantum chip 1, due to the close spatial distance between the quantum bits 15, their state changes may affect each other, resulting in signal crosstalk, thereby interfering with the control of the quantum bit 15. Therefore, this embodiment introduces a signal crosstalk measurement step based on the original feedback control method, and the probe 21 is arranged in the superconducting quantum interference detector 2 to measure the signal crosstalk between the quantum bits 15. The probe 21 can be a highly sensitive magnetic field sensor. When measuring the signal crosstalk between the quantum bits 15, the distance between the probe 21 and the quantum chip 1 is 0.1mm, so that the interference between the quantum bits 15 can be captured. The main control module not only receives weak magnetic signals from the superconducting quantum interference detector 2, but also receives signal crosstalk information from the probe 21. Based on this information, the main control module can more accurately evaluate the state of the quantum bit 15. It can be understood that this embodiment further improves the accuracy and reliability of the quantum measurement and control signal feedback method by introducing the signal crosstalk measurement step.

[0041] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0042] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A quantum measurement and control signal feedback device based on weak magnetic field detection, characterized in that: include: A quantum chip (1), the quantum chip comprising an input end (11) and an output end (12), and a plurality of signal transmission lines (13) connected between the input end and the output end, the signal transmission line (13) comprising a first signal node (14), a quantum bit (15) being connected between the first signal node (14) and the output end (12), the input end (11) being used to receive a control signal; A control signal generating module, used to generate a first control signal for controlling a quantum bit in the quantum chip, wherein the first control signal is transmitted in the plurality of signal transmission lines and generates a stray magnetic field; A superconducting quantum interference device detector (2) used to detect a weak magnetic signal generated by a stray magnetic field at the first signal node (14); The main control module is used to compare the first control signal with the weak magnetic signal and generate a feedback control signal, wherein the feedback control signal is used to adjust the weak magnetic signal to be consistent with the first control signal.

2. The feedback device according to claim 1, characterized in that: The superconducting quantum interference device detector (2) is provided with a probe (21), the projection area of ​​the probe being less than 0.1 mm 2 , the distance between the probe and the quantum chip is N, 0.1 mm <N<5mm。 3. The feedback device according to claim 2, characterized in that: The distance between the probe and the quantum chip is N=1 mm.

4. The feedback device according to claim 1, characterized in that: The feedback control signal inverts the difference between the first control signal and the weak magnetic signal, and is transmitted to the first signal node (14) through a feedback loop to compensate for the fluctuation of the first control signal, so that the weak magnetic signal is consistent with the first control signal.

5. The feedback device according to claim 1, characterized in that: The quantum chip includes a plurality of quantum gates for performing logical operations or quantum operations on quantum bits. The quantum gates operate based on the logical states of the quantum bits to achieve processing and transformation of quantum information.

6. The feedback device according to claim 1, characterized in that: The main control module also includes a signal amplification unit, which is used to amplify the weak magnetic signal detected by the superconducting quantum interference device detector.

7. The feedback device according to claim 1, characterized in that: The main control module also includes a signal filtering unit, which is used to filter the weak magnetic signal detected by the superconducting quantum interference device detector.

8. The feedback device according to claim 1, characterized in that: The main control module further includes a comparator, and the comparator is used to compare the difference between the weak magnetic signal and the first control signal.

9. A quantum measurement and control signal feedback method based on weak magnetic field detection, characterized in that: The quantum measurement and control signal feedback method is applied to the quantum measurement and control signal feedback device according to any one of claims 1 to 8, comprising the following steps: Generating a first control signal for controlling a quantum bit in a quantum chip (1) through the control signal generation module and transmitting the first control signal to an input end (11) of the quantum chip; The first control signal is transmitted in the plurality of signal transmission lines (13) and generates a stray magnetic field; Detecting a weak magnetic signal generated by a stray magnetic field at the first signal node (14) by means of the superconducting quantum interference device detector (2); The main control module compares the weak magnetic signal with the first control signal and generates a feedback control signal, wherein the feedback control signal is used to adjust the weak magnetic signal to be consistent with the first control signal.

10. The quantum measurement and control signal feedback method according to claim 9, characterized in that: The following steps are also included: The signal crosstalk between the quantum bits (15) is measured by a probe (21) arranged in the superconducting quantum interference device detector (2) and fed back to the main control module.

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