A quantum computer, a measurement and control system and an attenuation adjustment method

Abstract

This application discloses a quantum computer, a measurement and control system, and an attenuation adjustment method, applicable to the field of quantum technology. The system includes: a signal output circuit for outputting measurement signals to a quantum processor; a signal readout circuit for receiving and processing feedback signals; an attenuator for signal attenuation in the signal output circuit, and a switch group cooperating with the attenuator; the attenuator includes N attenuation units, and when the measurement and control system is operating, the quantum processor, attenuator, and switch group are placed in a dilution refrigerator so that the attenuator is in a cooling environment provided by the dilution refrigerator; a switch controller controls the state of the switch group to adjust the circuit connection structure of the N attenuation units in the attenuator, thereby adjusting the attenuation value of the attenuator. Applying this solution can effectively reduce the impact of thermal noise, reduce the complexity of the operator's work, improve measurement and control efficiency, and reduce the hardware requirements for arbitrary waveform generators.

Description

Technical Field

[0001] This invention relates to the field of quantum technology, and in particular to a quantum computer, a measurement and control system, and a method for adjusting attenuation. Background Technology

[0002] Superconducting quantum computing is the mainstream quantum computing technology today, obtaining the results of quantum algorithms by characterizing the state of superconducting qubits in a near-absolute-zero environment. Currently, before a superconducting quantum computer leaves the factory, and after the superconducting quantum chip in a superconducting quantum computer is replaced, it is necessary to measure some parameters of the superconducting quantum chip to verify product performance and provide references for customers. To obtain these parameters, a measurement and control system typically transmits various measurement signals to the superconducting quantum chip and reads the feedback signals returned by the superconducting quantum chip. However, the power differences between these measurement signals can be significant. For example, searching for information about the resonant cavity of the superconducting quantum chip requires a relatively high-power measurement signal, while searching for dispersion information about the coupling between the resonant cavity and the qubit requires a relatively low-power measurement signal.

[0003] Currently, room-temperature radio frequency signal generation units (including or arbitrary waveform generators) are typically used in the measurement and control systems of superconducting quantum computers to generate measurement signals of varying power. These signals are then attenuated by attenuators to meet power requirements under different conditions. Furthermore, some attenuators are currently installed in measurement and control systems operating at room temperature, while others are located in dilution refrigerators (to provide an ultra-low temperature environment for the superconducting quantum chip). During parameter measurement, attenuators operating at room temperature can have their attenuation values ​​manually adjusted, while attenuators operating in ultra-low temperature environments cannot be manually adjusted.

[0004] One current approach uses low-cost arbitrary waveform generators with a narrow adjustable power range. During parameter measurement, since the measured parameter value is unknown and the attenuator in the ultra-low temperature environment cannot be manually adjusted, this approach requires staff to continuously adjust the attenuator in the room temperature environment until the power requirement of the current test is met. This approach can easily introduce thermal noise into the quantum bit readout circuit, thereby affecting the performance of the superconducting quantum chip.

[0005] In addition, some solutions use arbitrary waveform generators with a wide adjustable power range, which are more expensive. Furthermore, even if such arbitrary waveform generators can provide lower power output, it is generally still necessary to set up partial attenuators at room temperature and in the dilution refrigerator. By manually adjusting the attenuators in the room temperature environment, the power output to the superconducting quantum chip can meet the power requirements of the current test.

[0006] In the above schemes, staff need to manually adjust the attenuator in the room temperature environment, which increases the complexity of the operation, cannot guarantee the testing efficiency, and can easily introduce thermal noise into the quantum bit reading line.

[0007] In summary, how to effectively measure and control superconducting quantum chips, reduce the workload of staff, improve testing efficiency, and reduce the impact of thermal noise to ensure the performance of superconducting quantum chips are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a quantum computer, a measurement and control system, and an attenuation adjustment method to effectively realize the measurement and control of the quantum processor, reduce the workload of staff, improve efficiency, and reduce the impact of thermal noise, thereby ensuring the performance of the quantum processor.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

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

[0011] Signal output circuit, used to output measurement signals to the quantum processor;

[0012] A signal readout circuit is used to receive a feedback signal corresponding to the measurement signal output by the quantum processor, and to process the feedback signal.

[0013] 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.

[0014] 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.

[0015] In one embodiment, the switch controller is specifically used for:

[0016] 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.

[0017] Where M is an integer and M≤N, and the value of M is controlled by the switch controller.

[0018] In one embodiment, the switch group includes a first switch to an N+1th switch, and the on / off state of each switch is controlled by the switch controller.

[0019] 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.

[0020] 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.

[0021] In one embodiment, the switch group is a switch group with interlocking function, such that at any given time, only one of the switches from the 1st to the N+1th is allowed to be in the on state, while the remaining switches are in the off state.

[0022] In one embodiment, the switch group further includes a main switch;

[0023] 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.

[0024] In one embodiment, 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.

[0025] In one embodiment, 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.

[0026] 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.

[0027] In one embodiment, the switch assembly is a switch assembly in which both the conductor material and the contact material are made of a metal material with a resistivity lower than a set threshold, and the switch material is a low-temperature superconducting alloy material.

[0028] Secondly, the present invention provides a quantum computer, including the measurement and control system as described above.

[0029] Thirdly, the present invention provides an attenuation adjustment method. The measurement and control system includes: a signal output circuit for outputting a measurement signal to a quantum processor; a signal reading circuit for receiving a feedback signal corresponding to the measurement signal output by the quantum processor and processing the feedback signal; the signal output circuit is provided with a radio frequency signal generation unit for transmitting a signal, an attenuator for signal attenuation, and a switch group cooperating 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; wherein, N is a positive integer;

[0030] The attenuation adjustment method is applied to the switch controller connected to the switch group, including:

[0031] The state of the switch group is controlled to adjust the circuit connection structure of the N attenuation units in the attenuator, thereby adjusting the attenuation value of the attenuator.

[0032] The measurement and control system, based on the technical solution provided in this invention, includes: a signal output circuit for outputting measurement signals to a quantum processor; a signal reading circuit for receiving feedback signals corresponding to the measurement signals output by the quantum processor and processing these feedback signals; and a switch controller connected to a switch group. Considering that thermal noise introduced on the reading line can affect the performance of the quantum processor, the attenuator and switch group in the signal output circuit of this application can both be placed in a dilution refrigerator. This allows the attenuator to be in a cooling environment provided by the dilution refrigerator, effectively reducing the impact of thermal noise and eliminating the need to set the attenuator at room temperature, thus enabling more accurate and stable reading of the quantum processor's state. Furthermore, the signal output circuit includes a switch group that works in conjunction with the attenuator. The switch group is connected to the switch controller, allowing for adjustments to the signal attenuation level at any time during measurement and control, even when the attenuator is in a set low-temperature environment. Specifically, the attenuator includes 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, thus changing the attenuation value of the attenuator. In other words, under the control of the switch controller, the attenuation value of the attenuator can be adjusted at any time through the switch group, which effectively reduces the workload of the staff and improves the measurement and control efficiency. Furthermore, since this application supports adjusting the attenuator value at any time, the measurement signal output by the quantum processor can effectively reach the required power. Therefore, this application has lower requirements for the arbitrary waveform generator in the signal output circuit; for example, a low-cost arbitrary waveform generator with a narrow adjustable power range can be used.

[0033] In summary, the solution proposed in this application can effectively reduce the impact of thermal noise, enabling more accurate and stable state reading of the quantum processor. This effectively reduces the workload for operators and improves measurement and control efficiency. Furthermore, the solution has lower requirements for the arbitrary waveform generator, supporting the use of arbitrary waveform generators with a narrow adjustable power range, thus reducing the hardware specifications required for the arbitrary waveform generator. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of a measurement and control system provided in a specific embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the attenuator and switch group in a specific embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of a switch group implemented by a relay in a specific embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the structure of a single attenuation unit in a specific embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the attenuator and switch group in another specific embodiment of the present invention. Detailed Implementation

[0040] The core of this invention is to provide a quantum computer, a measurement and control system, and an attenuation adjustment method, which can effectively reduce the impact of thermal noise, enabling more accurate and stable state reading of the quantum processor. This effectively reduces the workload of operators and improves measurement and control efficiency. Furthermore, the solution of this application has lower requirements for the arbitrary waveform generator, supporting the use of arbitrary waveform generators with a narrow adjustable power range, thus reducing the hardware specifications requirements for the arbitrary waveform generator.

[0041] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a measurement and control system provided in a specific embodiment of the present invention. The measurement and control system may include:

[0043] Signal output circuit 100 is used to output measurement signals to the quantum processor;

[0044] The signal output circuit 100 includes a radio frequency signal generation unit 40 for transmitting signals, an attenuator 10 for signal attenuation, and a switch group 20 that works in conjunction with the attenuator 10. The attenuator 10 includes N attenuation units, and when the measurement and control system is working, the quantum processor, the attenuator 10, and the switch group 20 are placed in a dilution refrigerator so that the quantum processor, the attenuator 10, and the switch group 20 are in a cooling environment provided by the dilution refrigerator; where N is a positive integer.

[0045] The switch controller 30, which is connected to the switch group 20, is used to control the state of the switch group 20 so as to adjust the circuit connection structure of the N attenuation units in the attenuator 10, thereby adjusting the attenuation value of the attenuator 10.

[0046] Further reading is available. Figure 1 The measurement and control system may also include a signal reading circuit 200, which is used to receive the feedback signal corresponding to the measurement signal output by the quantum processor and to process the feedback signal.

[0047] Specifically, the signal output circuit 100 can output measurement signals to the quantum processor. Typically, under the control of a host computer, it outputs measurement signals specified by the host computer to the quantum processor. For example, the host computer can control the radio frequency signal generation unit 40 in the signal output circuit 100, thereby enabling the signal output circuit 100 to output measurement signals specified by the host computer to the quantum processor. The radio frequency signal generation unit 40 can include or be an arbitrary waveform generator to achieve the purpose of transmitting high-frequency signals. This application does not limit the arbitrary waveform generator; it can use a low-cost arbitrary waveform generator with a narrow adjustable power range, or it can use an arbitrary waveform generator with a wide adjustable power range.

[0048] The specific structure of the signal output circuit 100 can be set and adjusted according to actual needs, as long as it can effectively output measurement signals to the quantum processor. However, a typical signal output circuit 100 will include a radio frequency signal generation unit 40 for providing a signal source and an attenuator 10 for signal attenuation. In some signal output circuits 100, structures such as filters, power dividers, and operational amplifiers may also be included as needed, without affecting the implementation of this invention.

[0049] After the signal output circuit 100 outputs a measurement signal to the quantum processor, the signal reading circuit 200 can receive the feedback signal corresponding to the measurement signal output by the quantum processor and 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, it can be equipped with filters, attenuators, operational amplifiers, etc., without affecting the implementation of the present invention.

[0050] Quantum processors can take many forms. For example, they can be superconducting quantum chips used for superconducting quantum computing, requiring operation in a near-absolute-zero environment. After the signal readout circuit 200 processes the feedback signal from the superconducting quantum chip, it can read the state of the superconducting qubits. Alternatively, they can be quantum processors in semiconductor quantum computers or ion trap quantum computers, which also require operation in a low-temperature environment using a dilution refrigerator.

[0051] The signal output circuit 100 includes an attenuator 10 for signal attenuation and a switch group 20 that works in conjunction with the attenuator 10. The attenuator 10 comprises N attenuation units. Under the control of the switch controller 30, the state of the switch group 20 can be adjusted, thereby adjusting the circuit connection structure of the N attenuation units in the attenuator 10, thus achieving the adjustment of the attenuation value of the attenuator 10. When the switch controller 30 adjusts the state of the switch group 20, thereby adjusting the circuit connection structure of the N attenuation units, there are various possible implementation methods. For example, the attenuation value can be adjusted by changing the series-parallel connection relationship between the N attenuation units.

[0052] In one specific embodiment of the present invention, the switch controller 30 is specifically used for:

[0053] The state of the control switch group 20 is used to adjust the circuit connection structure of N attenuation units in the attenuator 10, thereby adjusting the attenuation value of the attenuator 10. The circuit connection structure is adjusted such that M attenuation units are connected in series between the input and output terminals of the attenuator 10, where M is an integer and M≤N, and the value of M is controlled by the switch controller 30.

[0054] This implementation takes into account that the more attenuation units connected in series between the input and output terminals of attenuator 10, the greater the signal attenuation; conversely, the fewer attenuation units connected in series between the input and output terminals of attenuator 10, the smaller the signal attenuation. Therefore, when the switch controller 30 adjusts the circuit connection structure of N attenuation units, it only needs to adjust the number of attenuation units connected in series between the input and output terminals of attenuator 10 to effectively increase / decrease the attenuation value of attenuator 10 and achieve linear adjustment of the attenuation value.

[0055] In this embodiment, the switch controller 30 can adjust the circuit connection structure so that M attenuation units are connected in series between the input and output terminals of the attenuator 10. Furthermore, this embodiment adjusts the attenuation value of the attenuator 10 by adjusting the number of attenuation units connected in series between the input and output terminals of the attenuator 10. This is relatively simple and convenient to implement, effectively reducing the complexity of the circuit structure in the attenuator 10.

[0056] Of course, in other embodiments, the switch controller 30 can adjust the circuit connection structure by adjusting the series / parallel connection relationship between the N attenuation units in the attenuator 10, thereby achieving a more refined attenuation value adjustment. For example, the N attenuation units are divided into X groups connected in series, each group includes one or more N attenuation units connected in parallel, each attenuation unit in each group is connected in series with a switch, and each group is provided with a switch that serves as a bypass for that group. Then, by controlling the on / off state of the switch in each group, the switch controller 30 can achieve a refined adjustment of the circuit connection structure of the N attenuation units, that is, achieve a more refined attenuation value adjustment.

[0057] In one specific embodiment of the present invention, the switch group 20 includes a first switch to an N+1th switch, and the on / off state of each switch is controlled by the switch controller 30.

[0058] The attenuator 10 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 first attenuation unit serves as the input end of the attenuator 10.

[0059] 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 connected to each other, and the connection ends serve as the output ends of the attenuator 10.

[0060] This implementation takes into account that the switch controller 30 should be able to adjust the circuit connection structure of N attenuation units through the switch group 20 so that M attenuation units are connected in series between the input and output terminals of the attenuator 10. A more convenient way is to implement the switch group 20 through the 1st to the N+1th switches.

[0061] For easier understanding, please refer to the following: Figure 2 This is a schematic diagram of the attenuator 10 and the switch group 20 in one specific embodiment. Figure 2 This example uses N=4; in other implementations, N can be set to other values ​​as needed. In this implementation, since N=4, the four attenuation units are connected sequentially, requiring five switches. The first terminal of the first switch is connected to the first terminal of the first attenuation unit, the first terminal of the second switch is connected to the second terminal of the first attenuation unit, and the first terminal of the (i+1)th switch is connected to the second terminal of the ith attenuation unit. Furthermore, the second terminals of each switch are interconnected, and these connections serve as the output terminals of the attenuator 10.

[0062] 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.

[0063] 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.

[0064] Furthermore, in one specific embodiment of the present invention, 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.

[0065] 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.

[0066] 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 3Relay A in the diagram is a single-pole 5-throw relay, meaning that relay A is used to implement the functions of the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, and the fifth switch S5. It can be seen that... Figure 3 By using a single-pole 5-throw relay A to implement switch group 20, interlocking can be achieved in the hardware structure, so that at most one of the switches from the 1st to the N+1th can be in the on state at the same time.

[0067] In one specific embodiment of the present invention, the switch controller 30 has a voltage control port, such that the switch controller 30 controls the value of M based on the voltage magnitude of the voltage control port.

[0068] The switch controller 30 needs to control the switch group 20, thereby connecting M attenuation units in series between the input and output terminals of the attenuator 10. In other words, the specific value of M, i.e., how many attenuation units need to be connected in series between the input and output terminals of the attenuator 10, can be determined by the switch controller 30. For example, in practical applications, during the measurement and control of the bare cavity state or dispersion state of the quantum processor, the operator continuously adjusts the attenuation value of the attenuator 10 through control commands until the current attenuator 10 meets the usage requirements.

[0069] This implementation takes into account that using the voltage of the voltage control port to control the value of M is simple and convenient to implement, and can be achieved without setting up complex communication logic. Therefore, a voltage control port is provided 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.

[0070] 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.

[0071] 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.

[0072] In one specific embodiment, the switch group 20 may further include a main switch;

[0073] 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.

[0074] 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.

[0075] When the measurement and control system is working, in this application, the quantum processor, attenuator 10, and switch group 20 need to be placed in a dilution refrigerator so that the quantum processor, attenuator 10, and switch group 20 are all in a set low-temperature environment, that is, in the cooling environment provided by the dilution refrigerator, thereby effectively reducing the influence of thermal noise and enabling more accurate and stable reading of the quantum processor's state. For example, in one specific embodiment, the attenuator 10 and switch group 20 are specifically placed in a PT2 layer with a temperature of approximately 4 Kelvin inside the dilution refrigerator.

[0076] The specific structure of each attenuation unit of attenuator 10 can be set and adjusted according to actual needs. Considering that the frequency range of the measurement signals used in superconducting quantum computing is usually 4-8 GHz, attenuator 10 needs to ensure flat attenuation characteristics in the 4-8 GHz band without causing significant frequency dependence. The core materials of attenuator 10 include silicon carbide (SiC), PTFE, and gold-plated beryllium copper.

[0077] Each attenuation unit can, for example, employ a stable T-shaped attenuation network to ensure good attenuation characteristics. Specifically, in one embodiment of the present invention, the structure of each attenuation unit in the attenuator 10 is identical, as can be found in [reference needed]. Figure 4 Each attenuation unit may include: a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4;

[0078] 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.

[0079] In this embodiment, the attenuation unit implemented by four resistors 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 the same.

[0080] However, it is understood that the attenuation unit in the attenuator 10 of the present invention may also adopt other suitable circuit structures, and is not limited to the T-shaped attenuation network described above.

[0081] In one specific embodiment of the present invention, the switch group 20 is a switch group 20 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.

[0082] This implementation takes into account that since the cooling capacity of most dilution refrigerators is largely distributed in the 4K environment, approximately on the order of 1.5 watts, the materials of the switch assembly 20 of this application can be designed so that the switch assembly 20 does not generate excessive energy during operation.

[0083] Specifically, in this embodiment, the conductor and contact materials of the switch assembly 20 are both made of metallic materials with resistivity lower than a set threshold. For example, the conductor and contact materials of the switch assembly 20 can be silver or oxygen-free copper to ensure that the resistivity is lower than the set threshold. The switch material can be a niobium-titanium alloy that has superconductivity at low temperatures to effectively reduce heat generation.

[0084] The measurement and control system, based on the technical solution provided in this invention, includes: a signal output circuit for outputting measurement signals to a quantum processor; a signal reading circuit for receiving feedback signals corresponding to the measurement signals output by the quantum processor and processing these feedback signals; and a switch controller connected to a switch group. Considering that thermal noise introduced on the reading line can affect the performance of the quantum processor, the attenuator and switch group in the signal output circuit of this application can both be placed in a dilution refrigerator. This allows the attenuator to be in a cooling environment provided by the dilution refrigerator, effectively reducing the impact of thermal noise and eliminating the need to set the attenuator at room temperature, thus enabling more accurate and stable reading of the quantum processor's state. Furthermore, the signal output circuit includes a switch group that works in conjunction with the attenuator. The switch group is connected to the switch controller, allowing for adjustments to the signal attenuation level at any time during measurement and control, even when the attenuator is in a set low-temperature environment. Specifically, the attenuator includes 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, thus changing the attenuation value of the attenuator. In other words, under the control of the switch controller, the attenuation value of the attenuator can be adjusted at any time through the switch group, which effectively reduces the workload of the staff and improves the measurement and control efficiency. Furthermore, since this application supports adjusting the attenuator value at any time, the measurement signal output by the quantum processor can effectively reach the required power. Therefore, this application has lower requirements for the arbitrary waveform generator in the signal output circuit; for example, a low-cost arbitrary waveform generator with a narrow adjustable power range can be used.

[0085] In summary, the solution proposed in this application can effectively reduce the impact of thermal noise, enabling more accurate and stable state reading of the quantum processor. This effectively reduces the workload for operators and improves measurement and control efficiency. Furthermore, the solution has lower requirements for the arbitrary waveform generator, supporting the use of arbitrary waveform generators with a narrow adjustable power range, thus reducing the hardware specifications required for the arbitrary waveform generator.

[0086] Corresponding to the above embodiments of the measurement and control system, this invention also provides a quantum computer, which may include the measurement and control system as described in any of the above embodiments. This can be referred to in conjunction with the above description and will not be repeated here. The quantum computer may be, for example, a superconducting quantum computer, a semiconductor quantum computer, an ion trap quantum computer, or other quantum computers that require operation in a low-temperature environment.

[0087] Corresponding to the above embodiment of the measurement and control system, this embodiment of the invention also provides an attenuation adjustment method, which can be referred to in conjunction with the above. The measurement and control system includes: a signal output circuit for outputting a measurement signal to a quantum processor; a signal readout circuit for receiving a feedback signal corresponding to the measurement signal output by the quantum processor and processing the feedback signal; the signal output circuit is provided with a radio frequency signal generation unit for transmitting signals, an attenuator for signal attenuation, and a switch group cooperating 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; where N is a positive integer;

[0088] This attenuation adjustment method is applied to a switch controller and may include: controlling the state of a switch group to adjust the circuit connection structure of N attenuation units in the attenuator based on the state of the switch group, so as to adjust the attenuation value of the attenuator.

[0089] Furthermore, this step can specifically include:

[0090] The state of the control switch group is used 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.

[0091] It should also be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0092] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. Specific examples have been used in this application to illustrate the principles and implementation methods of the invention. The description of the above embodiments is only for the purpose of helping to understand the technical solution and core ideas of the invention. It should be noted that those skilled in the art can make several improvements and modifications to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the invention.

Claims

1. A measurement and control system, characterized in that, include: Signal output circuit, used to output measurement signals to the quantum processor; A signal readout circuit is used to receive a feedback signal corresponding to the measurement signal output by the quantum processor, and to process the feedback signal. 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. A quantum computer, characterized in that, Includes the measurement and control system as described in any one of claims 1 to 8.

10. An attenuation adjustment method, characterized in that, The measurement and control system includes: a signal output circuit for outputting measurement signals to the quantum processor; a signal readout circuit for receiving feedback signals corresponding to the measurement signals output by the quantum processor and processing the 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 cooperating 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; where N is a positive integer; The attenuation adjustment method is applied to the switch controller connected to the switch group, including: The state of the switch group is controlled to adjust the circuit connection structure of the N attenuation units in the attenuator, thereby adjusting the attenuation value of the attenuator.

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