Quantum computer and measurement and control system

Abstract

The utility model discloses a quantum computer and a measurement and control system, which are applied to the technical field of quantum, and comprise a signal output circuit used for outputting a measurement signal to a quantum processor to obtain a corresponding feedback signal; the signal output circuit is internally provided with an attenuator used for signal attenuation and a switch group matched with the attenuator; the attenuator comprises N attenuation units, and when the measurement and control system works, the quantum processor, the attenuator and the switch group are arranged in the dilution refrigerator, so that the attenuator is in a refrigeration environment provided by the dilution refrigerator; and the switch controller is used for controlling the state of the switch group so as to adjust the circuit connection structure of the N attenuation units in the attenuator through the state of the switch group, so that the attenuation value of the attenuator is adjusted. By applying the scheme of the invention, the influence of thermal noise can be effectively reduced, the working complexity of workers is reduced, the measurement and control efficiency is improved, and the hardware index requirement on the arbitrary waveform generator can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to quantum technology field especially relates to a kind of quantum computer and measurement and control system. BACKGROUND

[0002] Superconducting quantum computing is the mainstream quantum computing today, by representing superconducting quantum bits in near absolute zero degree environment to obtain the result of quantum algorithm. At present, before the superconducting quantum computer is shipped and after the superconducting quantum chip in the superconducting quantum computer is replaced, some parameters in the superconducting quantum chip in the superconducting quantum computer need to be measured to realize verifying product performance, providing reference for customers and other purposes. In order to measure these parameters, the measurement and control system usually transmits various measurement signals to the superconducting quantum chip and reads the feedback signals transmitted back by the superconducting quantum chip. However, the power difference between these measurement signals can be large, for example, when searching for the resonant cavity information of the superconducting quantum chip, a relatively large power measurement signal is needed, and when searching for the dispersion information of the resonant cavity and quantum bit coupling of the superconducting quantum chip, a relatively small power measurement signal is needed.

[0003] At present, a room temperature radio frequency signal generating unit (including or being an arbitrary waveform generator) is usually used in the measurement and control system of the superconducting quantum computer to generate measurement signals of different powers, and an attenuator is used to attenuate the measurement signals to meet the power requirements in different situations. In addition, some attenuators are arranged in the measurement and control system working in room temperature conditions, and some attenuators are arranged in the dilution refrigerator (providing an ultra-low temperature environment for the operation of the superconducting quantum chip). In the parameter measurement process, the attenuator in the room temperature environment can be manually adjusted, but the attenuator operating in the ultra-low temperature environment cannot be manually adjusted.

[0004] In a current scheme, some low-cost arbitrary waveform generators with narrow adjustable power range are used. In the parameter measurement process, since the parameter values to be measured are unknown, and the attenuator in the ultra-low temperature environment cannot be manually adjusted, the staff needs to continuously adjust the attenuator in the room temperature environment until the power requirement of the current test is met. In such a scheme, it is easy to introduce thermal noise on the readout line of the quantum bit, thereby affecting the performance of the superconducting quantum chip.

[0005] In addition, some schemes use an arbitrary waveform generator with a wide adjustable power range, which is relatively high in cost. Moreover, even if such an arbitrary waveform generator can provide a lower power output, generally, a partial attenuator needs to be arranged in a room temperature environment and in a dilution refrigerator, so as to manually adjust the attenuator in the room temperature environment, so that the power output to the superconducting quantum chip can meet the current power requirement of the test.

[0006] In the above schemes, the staff needs to manually adjust the attenuator in the room temperature environment, which increases the operation complexity of the staff, cannot guarantee the test efficiency, and is easy to introduce thermal noise on the readout line of the qubit.

[0007] To sum up, how to effectively realize the measurement and control of the superconducting quantum chip, reduce the work complexity of the staff, improve the test efficiency, and reduce the influence of thermal noise to guarantee the performance of the superconducting quantum chip is a technical problem that needs to be solved by the technical personnel in the field at present. Practical new type content

[0008] The purpose of the present application is to provide a quantum computer and a measurement and control system, so as to effectively realize the measurement and control of the quantum processor, reduce the work complexity of the staff, improve the efficiency, and reduce the influence of thermal noise to guarantee the performance of the quantum processor.

[0009] To solve the above technical problems, the present application provides the following technical solutions:

[0010] In a first aspect, the present application provides a measurement and control system, comprising:

[0011] A signal output circuit is used to output a measurement signal to the quantum processor to obtain a corresponding feedback signal;

[0012] The signal output circuit is provided with a radio frequency signal generating unit for transmitting a signal, an attenuator for attenuating the signal, and a switch group cooperating with the attenuator; the attenuator includes N attenuating units, and when the measurement and control system works, the quantum processor, the attenuator and the switch group are placed in a dilution refrigerator so that the quantum processor, the attenuator and the switch group are in the refrigeration environment provided by the dilution refrigerator; wherein N is a positive integer;

[0013] A switch controller connected with the switch group is used to control the state of the switch group, so as to adjust the circuit connection structure of the N attenuating units in the attenuator through the state of the switch group, so as to adjust the attenuation value of the attenuator.

[0014] In an embodiment, the switch controller is specifically used for:

[0015] controlling states of the switch group to adjust circuit connection structures of N attenuation units in the attenuator by the states of the switch group, so as to adjust attenuation values of the attenuator, and causing the circuit connection structures to be adjusted to be in series M attenuation units between an input terminal and an output terminal of the attenuator;

[0016] wherein M is an integer and M≤N, and a value of M is controlled by the switch controller.

[0017] In an embodiment, the switch group comprises a first switch to an (N+1)th switch, and on-off states of each switch are controlled by the switch controller.

[0018] The attenuator comprises N attenuation units, a first end of an ith attenuation unit is connected with a second end of an (i-1)th attenuation unit, i is a positive integer and 2≤i≤N, and a first end of a first attenuation unit is an input terminal of the attenuator.

[0019] A first end of an (i+1)th switch is connected with a second end of the ith attenuation unit, a first end of a second switch is connected with a second end of the first attenuation unit, a first end of a first switch is connected with a first end of the first attenuation unit, and second ends of the first switch to the (N+1)th switch are connected with each other, and a connection end is an output terminal of the attenuator.

[0020] In an embodiment, the switch group is a switch group with interlocking function, so that at the same time, only at most one switch of the first switch to the (N+1)th switch is in on state, and the rest switches are in off state.

[0021] In an embodiment, the switch group further comprises a total switch.

[0022] A first end of the total switch is the input terminal of the attenuator, and a second end of the total switch is connected with the first end of the first attenuation unit and the first end of the first switch respectively.

[0023] In an embodiment, the switch controller has a voltage control port, so that the switch controller controls the value of M based on a voltage size of the voltage control port.

[0024] In an embodiment, structures of each attenuation unit in the attenuator are the same, and each attenuation unit comprises a first resistor, a second resistor, a third resistor and a fourth resistor.

[0025] The first end of the first resistor is connected with the first end of the third resistor, and the connection end is as an input end of the attenuation unit; the second end of the first resistor is connected with the first end of the second resistor and the first end of the fourth resistor respectively; the second end of the second resistor is grounded; the second end of the third resistor is connected with the second end of the fourth resistor, and the connection end is as an output end of the attenuation unit.

[0026] In an embodiment, the switch group uses a metal material with resistivity lower than a set threshold value for both the wire material and the contact material, and uses a low-temperature superconducting alloy material for the switch material.

[0027] In an embodiment, the measurement and control system further comprises a signal reading circuit for receiving a feedback signal corresponding to the measurement signal output by the quantum processor and processing the feedback signal; and the quantum processor is a superconducting quantum chip.

[0028] In a second aspect, the utility model provides a kind of quantum computer, including the measurement and control system as described above.

[0029] The signal output circuit in the measurement and control system provided by the technical scheme of the embodiment of the utility model is provided with an attenuator and a switch group, and the attenuator and the switch group can be placed in a dilution refrigerator, so that the attenuator is in the refrigeration environment provided by the dilution refrigerator, the influence of thermal noise can be effectively reduced, and the state reading of the quantum processor can be more accurately and stably completed without setting the attenuator under room temperature conditions.The signal output circuit is provided with a switch group cooperating with the attenuator, and the switch group is connected with a switch controller, so that the attenuation degree of the attenuator can be adjusted at any time during the measurement and control process even if the attenuator is in a set low-temperature environment.The switch controller can control the state of the switch group, and when the state of the switch group is adjusted, the circuit connection structure of the N attenuators in the attenuator is also adjusted, and the attenuation value of the attenuator is changed.That is, under the control of the switch controller, the attenuation value of the attenuator can be adjusted at any time through the switch group, so that the work complexity of the staff can be effectively reduced and the measurement and control efficiency can be improved by the technical scheme of the utility model.The technical scheme of the utility model has low requirements for any waveform generator in the signal output circuit, and any waveform generator with low cost and narrow adjustable power range can be used.

[0030] In summary, the scheme of the application can effectively reduce the influence of thermal noise, so that the state reading of the quantum processor can be more accurately and stably completed. The working complexity of the staff is effectively reduced, and the measurement and control efficiency is improved. Moreover, the scheme of the application has lower requirements for the arbitrary waveform generator, supports the use of an arbitrary waveform generator with a narrow adjustable power range, that is, the hardware index requirements for the arbitrary waveform generator can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0032] Figure 1a The structure diagram of the measurement and control system provided by one specific embodiment of the present application is shown in the figure.

[0033] Figure 1b The structure diagram of the measurement and control system provided by another specific embodiment of the present application is shown in the figure.

[0034] Figure 2 The structure diagram of the attenuator and switch group in one specific embodiment of the present application is shown in the figure.

[0035] Figure 3 The structure diagram of the switch group realized by the relay in one specific embodiment of the present application is shown in the figure.

[0036] Figure 4 The structure diagram of a single attenuation unit in one specific embodiment of the present application is shown in the figure.

[0037] Figure 5 The structure diagram of the attenuator and switch group in another specific embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0038] The core of the present application is to provide a quantum computer and a measurement and control system, which can effectively reduce the influence of thermal noise, so that the state reading of the quantum processor can be more accurately and stably completed. The working complexity of the staff is effectively reduced, and the measurement and control efficiency is improved. Moreover, the scheme of the application has lower requirements for the arbitrary waveform generator, supports the use of an arbitrary waveform generator with a narrow adjustable power range, that is, the hardware index requirements for the arbitrary waveform generator can be reduced.

[0039] In order to make the person skilled in the art better understand the scheme of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0040] Please refer to Figure 1a , Figure 1a The structure diagram of the measurement and control system provided by the embodiment of the present application, which can include:

[0041] The signal output circuit 100 is used for outputting the measurement signal to the quantum processor to obtain the corresponding feedback signal.

[0042] The signal output circuit 100 is provided with a radio frequency signal generating unit 40 for transmitting signals, an attenuator 10 for signal attenuation, and a switch group 20 cooperating with the attenuator 10. The attenuator 10 includes N attenuation units, and when the measurement and control system works, the quantum processor, the attenuator 10 and the switch group 20 are placed in the dilution refrigerator so that the quantum processor, the attenuator 10 and the switch group 20 are in the refrigeration environment provided by the dilution refrigerator; wherein N is a positive integer.

[0043] The switch controller 30 connected with the switch group 20 is used for controlling the state of the switch group 20 to adjust the circuit connection structure of the N attenuation units in the attenuator 10 through the state of the switch group 20, so as to adjust the attenuation value of the attenuator 10.

[0044] Further, please refer to Figure 1b The structure diagram of the measurement and control system provided by another embodiment of the present application, which can further include a signal reading circuit 200 for receiving the feedback signal corresponding to the measurement signal output by the quantum processor and processing the feedback signal. The quantum processor may, for example, be a superconducting quantum chip.

[0045] Specifically, the signal output circuit 100 can output a measurement signal to the quantum processor, and generally under the control of the host computer, output a measurement signal specified by the host computer to the quantum processor. For example, the host computer can control the radio frequency signal generating unit 40 in the signal output circuit 100, so that the signal output circuit 100 can output a measurement signal specified by the host computer to the quantum processor. The radio frequency signal generating unit 40 can include or be an arbitrary waveform generator to achieve the purpose of transmitting high-frequency signals, and the present application has no limitation on the arbitrary waveform generator. A low-cost, narrow adjustable power range arbitrary waveform generator can be used, or a wide adjustable power range arbitrary waveform generator can be used.

[0046] The specific structure of the signal output circuit 100 can be set and adjusted according to actual needs, and can effectively output a measurement signal to the quantum processor. However, the radio frequency signal generating unit 40 for providing a signal source and the attenuator 10 for signal attenuation are usually provided in the signal output circuit 100. In some signal output circuits 100, structures such as filters, power dividers, and operational amplifiers can also be provided according to actual needs, without affecting the implementation of the present application.

[0047] After the signal output circuit 100 outputs a measurement signal to the quantum processor, the signal reading circuit 200 can receive a feedback signal corresponding to the measurement signal output by the quantum processor, and can process the feedback signal. Similarly, the specific structure of the signal output circuit 100 can be set and adjusted according to actual needs, for example, filters, attenuators, operational amplifiers, and other structures can be provided, without affecting the implementation of the present application.

[0048] The specific form of the quantum processor can also be various, for example, it can be a superconducting quantum chip for implementing superconducting quantum computing, which needs to be operated in a near-absolute zero environment. After the signal reading circuit 200 processes the feedback signal of the superconducting quantum chip, the reading of the superconducting quantum bit state can be completed. For example, it can be a quantum processor in a semiconductor quantum computer or an ion trap quantum computer, which also needs to be operated in a low-temperature environment through a dilution refrigerator.

[0049] The signal output circuit 100 is provided with an attenuator 10 for signal attenuation and a switch group 20 cooperating with the attenuator 10. The attenuator 10 comprises N attenuation units, under the control of a switch controller 30, the state of the switch group 20 can be adjusted, and then the circuit connection structure of the N attenuation units in the attenuator 10 is adjusted through the state of the switch group 20, so as to realize the adjustment of the attenuation value of the attenuator 10. When the switch controller 30 adjusts the state of the switch group 20 and then adjusts the circuit connection structure of the N attenuation units, there are many specific implementation manners, for example, the attenuation value can be adjusted by changing the series-parallel relationship between the N attenuation units.

[0050] In one specific embodiment of the utility model, the switch controller 30 is specifically used for:

[0051] Controlling the state of the switch group 20 to adjust the circuit connection structure of the N attenuation units in the attenuator 10 through the state of the switch group 20, to adjust the attenuation value of the attenuator 10, and the circuit connection structure is adjusted to: M attenuation units are connected in series between the input end and the output end of the attenuator 10, wherein M is an integer and M≤N, and the value of M is controlled by the switch controller 30.

[0052] This kind of embodiment considers that the more attenuation units connected in series between the input end and the output end of the attenuator 10, the greater the attenuation degree of the signal, on the contrary, the less attenuation units connected in series between the input end and the output end of the attenuator 10, the smaller the attenuation degree of the signal, therefore, when the switch controller 30 adjusts the circuit connection structure of the N attenuation units, it only needs to adjust the number of attenuation units connected in series between the input end and the output end of the attenuator 10, so as to effectively increase / decrease the attenuation value of the attenuator 10, and the linear adjustment of the attenuation value can be realized.

[0053] For this, the switch controller 30 in this kind of embodiment can make the circuit connection structure be adjusted to: M attenuation units are connected in series between the input end and the output end of the attenuator 10. And this kind of embodiment realizes the adjustment of the attenuation value of the attenuator 10 by adjusting the number of attenuation units connected in series between the input end and the output end of the attenuator 10, which is also relatively simple and convenient in implementation, and can effectively reduce the complexity of the circuit structure in the attenuator 10.

[0054] Of course, in other embodiments, the switch controller 30 can adjust the connection relationship between the N attenuation units in the attenuator 10 to realize the adjustment of the circuit connection structure, and realize more refined attenuation value adjustment, for example, the N attenuation units are divided into X groups connected in series, each group includes a single or multiple parallel N attenuation units, and each group of attenuation units is connected in series with a switch, and each group is provided with a switch for bypassing the group, and the switch controller 30 controls the on-off state of each group of switches, thereby realizing the refined adjustment of the circuit connection structure of the N attenuation units, that is, realizing more refined attenuation value adjustment.

[0055] In one specific embodiment of the present application, the switch group 20 includes the first switch to the N+1 switch, and the on-off state of each switch is controlled by the switch controller 30.

[0056] The attenuator 10 includes N attenuation units, the first end of the i attenuation unit is connected to the second end of the i-1 attenuation unit, i is a positive integer and 2≤i≤N, and the first end of the first attenuation unit is used as the input end of the attenuator 10.

[0057] The first end of the i+1 switch is connected to the second end of the i attenuation unit, the first end of the second switch is connected to the second end of the first attenuation unit, the first end of the first switch is connected to the first end of the first attenuation unit, and the second end of each switch in the first switch to the N+1 switch is connected to each other, and the connection end is used as the output end of the attenuator 10.

[0058] This embodiment considers that the switch controller 30 can adjust the circuit connection structure of the N attenuation units through the switch group 20, so that it is adjusted to be connected in series between the input end and the output end of the attenuator 10, and a more convenient way is to realize the switch group 20 through the first switch to the N+1 switch.

[0059] For easy understanding, please refer to Figure 2 , which is a structural schematic diagram of the attenuator 10 and the switch group 20 in one specific embodiment, Figure 2 , which is an example of N=4, and in other embodiments, N can be set to other values as needed. In this embodiment, N=4, so the four attenuation units are connected in series, and five switches are needed, the first end of the first switch is connected to the first end of the first attenuation unit, the first end of the second switch is connected to the second end of the first attenuation unit, and the first end of the i+1 switch is connected to the second end of the i attenuation unit. And the second end of each switch is connected to each other, and the connection end is used as the output end of the attenuator 10.

[0060] As can be seen from the connection relationship, when the switch controller 30 controls the i-th switch to be turned on and all other switches are turned off, i-1 attenuation units will be connected in series between the input and output terminals of the attenuator 10. Figure 2 For example, switch controller 30 controls Figure 2 When the first switch S1 is turned on and all other switches are turned off, zero attenuation units will be connected in series between the input and output terminals of attenuator 10. For example, switch controller 30 controls... Figure 2 When switch S3 is turned on and all other switches are turned off, two attenuation units will be connected in series between the input and output of attenuator 10. Switch controller 30 controls... Figure 2 When switch S5 is turned on and all other switches are turned off, four attenuation units will be connected in series between the input and output of attenuator 10, meaning that four attenuation units will be connected in series. Figure 2 In the example, all attenuation units achieved maximum attenuation.

[0061] Furthermore, the specific implementation of switches 1 to N+1 can be set and adjusted according to actual needs. For example, it can be implemented by means of switching transistors, relays, etc., as long as the switch controller 30 can effectively control the on and off of switches 1 to N+1.

[0062] Furthermore, in one specific embodiment of this utility model, the switch group 20 can be a switch group 20 with interlocking function, so that at any given time, only one of the switches from the first switch to the N+1th switch is allowed to be in the on state, and the remaining switches are in the off state.

[0063] As analyzed above, when the switch group 20 is implemented using the 1st to N+1th switches described above, the switch controller 30 controls the i-th switch to be turned on, and when all other switches are turned off, i-1 attenuation units will be connected in series between the input and output terminals of the attenuator 10. That is, at any given time, only the i-th switch specified by the control command needs to be turned on among the 1st to N+1th switches. Therefore, in this embodiment, the switch group 20 is equipped with an interlocking function, ensuring that at any given time, at most one switch among the 1st to N+1th switches is in the on state, while the rest are in the off state. This prevents other situations, such as the abnormal situation of two or more switches being turned on simultaneously, thereby further ensuring the reliability of the proposed solution and reducing the probability of errors in the attenuation value of the attenuator 10.

[0064] There are several ways to implement interlocking, including through hardware structures and software programs. Figure 3 For example, the interlocking switch group 20 required by this application is implemented using relays. Specifically, Figure 3The relay A in the switch group 20 is a single-pole five-throw relay, that is, the first switch S1, the second switch S2, the third switch S3, the fourth switch S4 and the fifth switch S5 are realized through the relay A. Figure 3 The switch group 20 realized by the single-pole five-throw relay A can realize interlocking in the hardware structure, so that at most only one switch in the first switch to the N+1 switch is in the on state at the same time.

[0065] In one specific embodiment of the utility model, the switch controller 30 has a voltage control port, so that the switch controller 30 controls the value of M based on the voltage of the voltage control port.

[0066] The switch controller 30 needs to control the switch group 20, so that M attenuation units are connected in series between the input end and the output end of the attenuator 10, that is, the value of M is how many attenuation units need to be connected in series between the input end and the output end of the attenuator 10 at present, which can be determined by the switch controller 30. For example, in actual application, the staff adjusts the attenuation value of the attenuator 10 through the control instruction in the process of measuring and controlling the bare cavity state or the dispersion state of the quantum processor, until the current attenuator 10 meets the use requirement.

[0067] This kind of embodiment considers that the value of M is controlled by the voltage of the voltage control port, which is simple and convenient to realize without setting complex communication logic, so that the voltage control port is set for the switch controller 30, so that the switch controller 30 can determine the value of M based on the voltage of the voltage control port.

[0068] For example, in one specific application, a 0-5V regulated DC power supply is used as the switch controller 30 in this application. This 0-5V regulated DC power supply has a voltage control port, which is connected to the switch group 20. The voltage of this voltage control port can be adjusted manually or by a program. When the voltage control port of the switch controller 30 outputs 0V to the switch group 20, the value of M is 0. That is, at this time, the switch controller 30 controls 0 attenuation units to be connected in series between the input and output terminals of the attenuator 10. For example, the attenuation value of the attenuator 10 is approximately 0dB at this time. When the voltage of the voltage control port increases by 100mV, the switch controller 30 can control the switch group 20 to switch positions once, increasing the attenuation value of the attenuator 10 by 10dB. For example, when the voltage of the voltage control port is 200mV, the value of M is 2. At this time, the switch controller 30 controls 2 attenuation units to be connected in series between the input and output terminals of the attenuator 10. For example, the attenuation value of the attenuator 10 is approximately 20dB at this time. For example, in this case, N=5. When the voltage at the voltage control port reaches 500mV, five attenuation units are connected in series between the input and output terminals of attenuator 10, reaching the maximum number. At this time, the attenuation value of attenuator 10 is 50dB and cannot be increased further.

[0069] Switch group 20 may have a power interface. For example, switch group 20 can be powered by a 12V power supply. When the power is turned off, switch group 20 will be turned off, that is, each switch in switch group 20 can be turned off, so that attenuator 10 is disconnected.

[0070] In one specific embodiment, the switch group 20 may further include a main switch;

[0071] The first terminal of the main switch serves as the input terminal of the attenuator, and the second terminal of the main switch is connected to the first terminal of the first attenuation unit and the first terminal of the first switch, respectively.

[0072] See also Figure 5 The diagram below shows the structure of attenuator 10 and switch group 20 in another specific embodiment. This embodiment also includes a main switch S0, allowing the on / off state of the attenuator to be determined by controlling the on / off state of the main switch S0. In practical applications, when switch group 20 receives 12V power, the main switch S0 automatically closes; conversely, when switch group 20 loses 12V power, the main switch S0 automatically opens, causing attenuator 10 to be open-circuited.

[0073] When the measurement and control system is working, in the scheme of the application, the quantum processor, the attenuator 10 and the switch group 20 need to be placed in the dilution refrigerator, so that the quantum processor, the attenuator 10 and the switch group 20 are all in the set low-temperature environment, that is, in the refrigeration environment provided by the dilution refrigerator, thereby effectively reducing the influence of thermal noise, so that the state reading of the quantum processor can be more accurately and stably completed. For example, in one specific embodiment, the attenuator 10 and the switch group 20 are specifically placed in the PT2 layer with a temperature of about 4 Kelvin in the dilution refrigerator.

[0074] The specific structure of each attenuation unit of the attenuator 10 can be set and adjusted according to actual needs. Considering that the frequency range of the measurement signal used in superconducting quantum computing is usually 4-8 GHz, the attenuator 10 needs to ensure flat attenuation characteristics in the 4-8 GHz frequency band and will not cause significant frequency dependence. The core material of the attenuator 10 includes silicon carbide (SiC), PTFE, and gold-plated beryllium copper.

[0075] Each attenuation unit may, for example, adopt a stable T-shaped attenuation network to ensure good attenuation characteristics. Specifically, in one specific embodiment of the application, the structure of each attenuation unit in the attenuator 10 is the same, and can be referred to in Figure 4 Each attenuation unit can include a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4.

[0076] The first end of the first resistor R1 is connected to the first end of the third resistor R3, and the connection end serves as the input end of the attenuation unit. The second end of the first resistor R1 is connected to the first end of the second resistor R2 and the first end of the fourth resistor R4, respectively. The second end of the second resistor R2 is grounded. The second end of the third resistor R3 is connected to the second end of the fourth resistor R4, and the connection end serves as the output end of the attenuation unit.

[0077] The attenuation unit realized by the four resistors in this embodiment is a T-shaped attenuation network, which has a simple structure and high reliability. The specific resistance values of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 can be set and adjusted according to actual needs, and the resistance values of the first resistor R1 and the fourth resistor R4 are usually consistent.

[0078] However, it can be understood that the attenuation unit in the attenuator 10 of the application can also adopt other suitable circuit structures, and is not limited to the T-shaped attenuation network described above.

[0079] In one specific embodiment of the application, the switch group 20 uses a metal material with a resistivity lower than a set threshold value for both the wire material and the contact material, and the switch group 20 uses a low-temperature superconducting alloy material.

[0080] The embodiment considers that, since the refrigeration capacity of most dilution refrigerators is largely distributed in a 4K environment, and the approximate order of magnitude is 1.5 watts, the material of the switch group 20 of the application can be designed so that the switch group 20 does not generate excessive energy during operation.

[0081] Specifically, in the embodiment, the wire material and the contact material of the switch group 20 are both metal materials with resistivity lower than a set threshold, for example, the wire material and the contact material of the switch group 20 can be silver or oxygen-free copper, so as to ensure that the resistivity is lower than the set threshold. The switch material can be niobium-titanium alloy with superconductivity at low temperature to effectively reduce the heat generation.

[0082] The technical scheme provided by the embodiment of the application is applied to the measurement and control system, which comprises: a signal output circuit, configured to output a measurement signal to a quantum processor to obtain a corresponding feedback signal, and a switch controller connected with the switch group. Considering that the thermal noise introduced on the readout line will affect the performance of the quantum processor, therefore, the attenuator and the switch group provided in the signal output circuit of the application can be placed in the dilution refrigerator, so that the attenuator is in the refrigeration environment provided by the dilution refrigerator, which can effectively reduce the influence of thermal noise, and there is no need to set the attenuator under room temperature conditions, so that the state reading of the quantum processor can be more accurately and stably completed. Moreover, the switch group cooperating with the attenuator is provided in the signal output circuit, and the switch group is connected with the switch controller, so that even if the attenuator is in a set low-temperature environment, the signal attenuation degree can still be adjusted at any time during the measurement and control process. Specifically, the attenuator comprises N attenuation units, and the switch controller can control the state of the switch group. When the state of the switch group is adjusted, the circuit connection structure of the N attenuation units in the attenuator is also adjusted, so that the attenuation value of the attenuator is changed. That is to say, under the control of the switch controller, the attenuation value of the attenuator can be adjusted at any time through the switch group, so that the application scheme can effectively reduce the working complexity of the staff and improve the measurement and control efficiency. Moreover, since the application scheme supports adjusting the attenuation value of the attenuator at any time, the measurement signal output to the quantum processor can effectively reach the required power by adjusting the attenuation value of the attenuator, so that the application scheme has a lower requirement for any arbitrary waveform generator in the signal output circuit, for example, an arbitrary waveform generator with lower cost and narrower adjustable power range can be used.

[0083] In summary, the application scheme can effectively reduce the influence of thermal noise, so that the state reading of the quantum processor can be more accurately and stably completed. The working complexity of the staff is effectively reduced, and the measurement and control efficiency is improved. Moreover, the application scheme has a lower requirement for the arbitrary waveform generator, supports using an arbitrary waveform generator with a narrower adjustable power range, that is, the hardware index requirement for the arbitrary waveform generator can be reduced.

[0084] Corresponding to the above embodiments of the measurement and control system, the embodiments of the utility model also provide a quantum computer, can include the measurement and control system in any one of the above embodiments, can be mutually corresponding with the above reference, this place does not repeat explanation again. The quantum computer can be superconducting quantum computer, semiconductor quantum computer, ion trap quantum computer and so on need to run in the quantum computer in low temperature environment.

[0085] It also needs to be explained that in the present application, such as first and second relationship terms such as only to distinguish one entity or operation from another entity or operation, and does not necessarily require or imply that there is any such actual relationship or order between the entities or operations. Moreover, the term "includes", "contains" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent in such process, article or equipment. Without more limitations, the element defined by the sentence "includes a" does not exclude the presence of another identical element in the process, article or equipment including the element.

[0086] The skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in the present application can be realized by electronic hardware, computer software or combination of both. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been described in the above description. Whether the functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different ways to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application. The principles and implementation of the present application are described by specific examples in the present application. The above example is only used to help understand the technical scheme of the present application and its core idea. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the present application.

Claims

1. A measurement and control system, characterized in that, include: The signal output circuit is used to output measurement signals to the quantum processor in order to obtain corresponding feedback signals. The signal output circuit includes a radio frequency signal generation unit for transmitting signals, an attenuator for signal attenuation, and a switch group that works in conjunction with the attenuator. The attenuator includes N attenuation units, and when the measurement and control system is working, the quantum processor, the attenuator, and the switch group are placed in a dilution refrigerator so that the quantum processor, the attenuator, and the switch group are in a cooling environment provided by the dilution refrigerator. Here, N is a positive integer. A switch controller connected to the switch group is used to control the state of the switch group, so as to adjust the circuit connection structure of the N attenuation units in the attenuator by adjusting the state of the switch group, thereby adjusting the attenuation value of the attenuator.

2. The measurement and control system according to claim 1, characterized in that, The switch controller is specifically used for: The state of the switch group is controlled to adjust the circuit connection structure of N attenuation units in the attenuator, thereby adjusting the attenuation value of the attenuator. The circuit connection structure is adjusted such that M attenuation units are connected in series between the input and output terminals of the attenuator. Where M is an integer and M≤N, and the value of M is controlled by the switch controller.

3. The measurement and control system according to claim 2, characterized in that, The switch group includes switches 1 to N+1, and the on / off state of each switch is controlled by the switch controller. The attenuator includes N attenuation units. The first end of the i-th attenuation unit is connected to the second end of the (i-1)-th attenuation unit. i is a positive integer and 2≤i≤N. The first end of the 1-th attenuation unit serves as the input end of the attenuator. The first end of the (i+1)th switch is connected to the second end of the i-th attenuation unit, the first end of the second switch is connected to the second end of the first attenuation unit, the first end of the first switch is connected to the first end of the first attenuation unit, and the second ends of each of the switches from the first switch to the (N+1)th switch are interconnected, and the connection ends serve as the output ends of the attenuator.

4. The measurement and control system according to claim 3, characterized in that, The switch group is a switch group with interlocking function, so that at any given time, at most one of the switches from the 1st to the N+1th is allowed to be in the on state, and the rest of the switches are in the off state.

5. The measurement and control system according to claim 3, characterized in that, The switch group also includes a main switch; The first terminal of the main switch serves as the input terminal of the attenuator, and the second terminal of the main switch is connected to the first terminal of the first attenuation unit and the first terminal of the first switch, respectively.

6. The measurement and control system according to claim 2, characterized in that, The switch controller has a voltage control port, such that the switch controller controls the value of M based on the voltage magnitude of the voltage control port.

7. The measurement and control system according to claim 1, characterized in that, Each attenuation unit in the attenuator has the same structure, and each attenuation unit includes: a first resistor, a second resistor, a third resistor, and a fourth resistor; The first end of the first resistor is connected to the first end of the third resistor, and the connection end serves as the input end of the attenuation unit. The second end of the first resistor is connected to the first end of the second resistor and the first end of the fourth resistor, respectively. The second end of the second resistor is grounded. The second end of the third resistor is connected to the second end of the fourth resistor, and the connection end serves as the output end of the attenuation unit.

8. The measurement and control system according to claim 1, characterized in that, The switch assembly is a switch assembly in which both the conductor material and the contact material are made of metal materials with resistivity lower than a set threshold, and the switch material is made of low-temperature superconducting alloy material.

9. The measurement and control system according to claim 1, characterized in that, The measurement and control system further includes a signal reading circuit for receiving a feedback signal output by the quantum processor corresponding to the measurement signal, and processing the feedback signal; the quantum processor is a superconducting quantum chip.

10. A quantum computer, characterized in that, Includes the measurement and control system as described in any one of claims 1 to 8.

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