Quantum device, oscillation frequency setting method, and program

Abstract

To enable, when frequency variable oscillators are connected to a common transmission line, reduction of crosstalk between the oscillators and utilization of the frequency variable capacity of the oscillators.SOLUTION: A quantum device comprises a plurality of oscillator groups, a plurality of circulators, and a transmission line common to the plurality of circulators. Each of the plurality of oscillator groups includes one or a plurality of frequency variable oscillators, and the one or the plurality of oscillators included in one oscillator group are connected to one port of one circulator common to the one or the plurality of oscillators. Each of the plurality of circulators is located in the transmission line so that a signal from a first end side of the transmission line is transmitted to the oscillator group side, and a signal from the oscillator group side is transmitted to a second end side of the transmission line, while a signal from the second end side to the oscillator group side and a signal from the oscillator group side to the first end side are both cut off.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a quantum device, an oscillation frequency setting method, and a program. [Background technology]

[0002] In quantum devices, signals may be transmitted in a multiplexed manner. For example, Patent Document 1 describes a superconducting microwave coupler in which multiple band-pass filters (BPFs) are connected to a single transmission line. In this superconducting microwave coupler, each of the band-pass filters has a different narrow passband, and transmits signals by frequency division multiplexing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-535169 Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple oscillators having frequency tunability, such as Josephson Parametric Oscillators (JPOs), are connected to a common transmission line, it is preferable to be able to reduce the effect of crosstalk between the oscillators and to utilize the frequency tunability of the oscillators.

[0005] An example of an object of the present invention is to provide a quantum device, an oscillation frequency setting method, and a program that can solve the above-mentioned problems. [Means for solving the problem]

[0006] According to a first aspect of the present invention, a quantum device comprises a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency tunability, one or more oscillators included in one oscillator group being connected to one port of one circulator common to the one or more oscillators, and each of the plurality of circulators is arranged on the transmission path so as to transmit signals from a first end side of the transmission path to the oscillator group side and transmit signals from the oscillator group side to a second end side of the transmission path, and to block signals both from the second end side to the oscillator group side and from the oscillator group side to the first end side.

[0007] According to a second aspect of the present invention, there is provided an oscillation frequency setting method, comprising: a plurality of oscillator groups; a plurality of circulators; and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency variability, the one or more oscillators included in one oscillator group being connected to one port of a circulator common to the one or more oscillators, each of the plurality of circulators transmitting a signal from a first end side of the transmission path to the oscillator group side, and transmitting a signal from the oscillator group side to the transmission path. a control device for controlling the quantum device that is arranged on the transmission line so as to transmit signals to a second end side of the transmission line and block signals from the second end side to the oscillator group side and from the oscillator group side to the first end side, and that sets the oscillation frequency of each oscillator for any combination of two oscillators included in different oscillator groups so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range defined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced.

[0008] According to a third aspect of the present invention, a program includes a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups includes one or more oscillators having frequency tunability, one or more oscillators included in one oscillator group are connected to one port of one circulator common to the one or more oscillators, and each of the plurality of circulators transmits a signal from a first end side of the transmission path to the oscillator group side, and transmits a signal from the oscillator group side to a second end side of the transmission path. and a quantum device arranged on the transmission path so as to block signals from both the second end side to the oscillator group side and from the oscillator group side to the first end side. The quantum device is configured to execute a program for causing a computer controlling the quantum device to execute the following: for any combination of two oscillators included in different oscillator groups, setting the oscillation frequency of each oscillator so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range defined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced. Effect of the Invention

[0009] According to the present invention, when oscillators having frequency tunability are connected to a common transmission line, it is possible to reduce the influence of crosstalk between the oscillators and to utilize the frequency tunability of the oscillators. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of a quantum device according to a first embodiment. [Diagram 2] 2 is a diagram illustrating an example of the configuration of an oscillator group according to the first embodiment. FIG. [Diagram 3] 3A to 3C are diagrams illustrating examples of arrangement of ports of the circulator according to the first embodiment. [Figure 4] FIG. 11 is a diagram illustrating an example of the configuration of a quantum device according to a second embodiment. [Diagram 5]FIG. 11 is a diagram illustrating an example of the configuration of a quantum device according to a third embodiment. [Figure 6] FIG. 13 is a diagram illustrating an example of the configuration of a quantum device according to a fourth embodiment. [Figure 7] FIG. 13 is a diagram showing an example of the oscillation frequency of a Josephson parametric oscillator in the quantum device according to the fifth embodiment. [Figure 8] FIG. 13 is a diagram showing an example of the oscillation frequency of a Josephson parametric oscillator in the quantum device according to the sixth embodiment. [Figure 9] FIG. 13 is a diagram illustrating an example of the configuration of a quantum computing system according to a seventh embodiment. [Figure 10] FIG. 1 is a diagram showing an example of the configuration of a quantum device used in an experiment. [Figure 11] FIG. 2 illustrates an example of the relationship between detuning and power of a signal incident on a Josephson parametric oscillator and readout fidelity of the Josephson parametric oscillator in accordance with at least one embodiment. [Figure 12] FIG. 13 is a diagram illustrating an example of the configuration of a quantum device according to an eighth embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of a processing procedure in an oscillation frequency setting method according to a ninth embodiment. [Figure 14] FIG. 1 is a schematic block diagram illustrating an example configuration of a computer in accordance with at least one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following describes embodiments of the present invention, but the following embodiments do not limit the scope of the invention. Also, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0012] <First embodiment> Fig. 1 is a diagram showing an example of the configuration of a quantum device according to the first embodiment. In the configuration shown in Fig. 1, the quantum device 1 includes N oscillator groups 15, N circulators 12, and one transmission line 18. Here, N is an integer N≧2.

[0013] When distinguishing between the N oscillator groups 15, the oscillator group 151, the oscillator group 152, . . . , the oscillator group 15 N When distinguishing between the N circulators 12, they are referred to as circulator 121, circulator 122, . . . , circulator 12 N It can also be written as: The oscillator group 15 and the circulator 12 are arranged in one-to-one correspondence. i and Circulator 12 i and are connected, where i is an integer such that 1≦i≦N.

[0014] The two ends of the transmission line 18 are also referred to as an input port 13 and an output port 14 . The input port 13 can be used as a port for inputting a signal to the oscillator group 15. The input port 13 corresponds to an example of a first end portion. The output port 14 can be used as a port for outputting signals from the oscillator group 15. The output port 14 corresponds to an example of a second end portion.

[0015] FIG. 2 is a diagram showing an example of the configuration of the oscillator group 15. In the configuration shown in FIG. i is M i 10 Josephson parametric oscillators and M i number of couplers 11, where M i is M i is an integer equal to or greater than 1. Each oscillator group 15 may include a different number of Josephson parametric oscillators 10, or may include the same number of Josephson parametric oscillators 10.

[0016] Oscillator Group 15 i M iWhen distinguishing between the Josephson parametric oscillators 10, the Josephson parametric oscillators 10 i_1 , Josephson Parametric Oscillator 10 i_2 , , Josephson Parametric Oscillator 10 i_Mi Also written as: Oscillator Group 15 i M i When distinguishing the couplers 11, i_1 , combiner 11 i_2 ,..., combiner 11 i_Mi It can also be written as:

[0017] The Josephson parametric oscillator 10 and the coupler 11 are arranged in one-to-one correspondence. i_j and coupler 11 i_j Here, j is 1≦j≦M. i is an integer. Oscillator Group 15 i M i For each of the Josephson parametric oscillators 10, the signal paths of the Josephson parametric oscillators 10 are combined into one via a coupler 11 and then fed to a circulator 12. i Both the signal input to the Josephson parametric oscillator 10 and the signal output from the Josephson parametric oscillator 10 are transmitted through this path. The input of a signal is also referred to as the incidence of a signal.

[0018] The Josephson parametric oscillator 10 continues to output a quantum signal while operating as a quantum bit upon receiving an input of a control signal called a pump signal. In addition, the frequency (oscillation frequency) of the quantum signal (oscillation signal) output by the Josephson parametric oscillator 10 can be changed by manipulating the frequency of the pump signal and the resonant frequency of the Josephson parametric oscillator 10 by applying a magnetic field. The ability to change the oscillation frequency is also referred to as frequency tunability.

[0019] In addition, since the Josephson parametric oscillator 10 is a resonator, when the frequency of a signal incident on the Josephson parametric oscillator 10 is different from the oscillation frequency, the Josephson parametric oscillator 10 has the property of reflecting the incident signal theoretically without loss. Here, when the frequency of a signal incident on the Josephson parametric oscillator 10 is different from the oscillation frequency, specifically, the difference between the frequency of the incident signal and the oscillation frequency is larger than the bandwidth of the Josephson parametric oscillator 10.

[0020] However, the oscillators included in the oscillator group 15 are not limited to Josephson parametric oscillators, and may be various oscillators having frequency tunability. The oscillators provided in the oscillator group 15 are also referred to as oscillators of the oscillator group 15 or oscillators included in the oscillator group 15.

[0021] The coupler 11 is a connection point between the Josephson parametric oscillator 10 and the circulator 12. The configuration of the coupler 11 is not limited to a specific configuration, and various configurations are possible that allow signals to be exchanged between the Josephson parametric oscillator 10 and the circulator 12. For example, the coupler 11 may be configured as capacitive coupling (a gap for junction). Alternatively, the coupler 11 may be configured using a resonator. Alternatively, the coupler 11 may be configured as inductive coupling (coupling by electromagnetic induction).

[0022] FIG. 3 is a diagram showing an example of the arrangement of ports of the circulator 12. As shown in FIG. Circulator 12 has three ports and transmits signals unidirectionally between the ports. The three ports of circulator 12 are also referred to as port 1, port 2, and port 3. Here, a signal input from port 1 of circulator 12 is output to port 2, and a signal input to port 2 is output to port 3. On the other hand, circulator 12 blocks signals from port 3 to port 2 and from port 2 to port 1.

[0023] In general, circulators are theoretically lossless, and can generally be made to have a wide bandwidth, for example several gigahertz (GHz) or greater. A circulator having four or more ports may be used as the circulator 12. In this case, the function of the circulator 12 may be realized by using three adjacent ports among the four or more ports.

[0024] 3, the circulator 12 is disposed on the transmission line 18 such that port 1 is located on the input port 13 side and port 3 is located on the output port 14 side. In addition, port 2 is connected to the oscillator group 15. Therefore, circulator 12 i The signal from the input port 13 of the transmission line 18 is input to the oscillator group 15. i The oscillator group 15 i The circulator 12 transmits a signal from the output port 14 of the transmission line 18. i The oscillator group 15 is connected to the output port 14. i side, and oscillator group 15 i The signal is blocked from both the input port 13 side and the output port 14 side. The input port 13 side is also referred to as the upstream side of the signal, and the output port 14 side is also referred to as the downstream side of the signal.

[0025] In addition, port 1 of the circulator 121 is connected to the input port 13. N-1 Port 3 is from circulator 122 to circulator 12 N Connected to port 1 of Circulator 12 N Port 3 of the input is connected to output port 14 .

[0026] The port 1 of the circulator 121 may be used as the input port 13. N The port 3 may be used as the output port 14 . In the following description, it is assumed that the quantum device 1 transmits signals by frequency division multiplexing. For this purpose, it is assumed that the oscillation frequencies of all the Josephson parametric oscillators 10 included in all the oscillator groups 15 are set to be different from each other.

[0027] However, two or more Josephson parametric oscillators 10 may have the same oscillation frequency. For example, the quantum device 1 may transmit input / output signals to the Josephson parametric oscillator 10 by using both time division multiplexing and frequency division multiplexing. In this case, the Josephson parametric oscillators 10 belonging to different groups in the time division multiplexing may have the same oscillation frequency.

[0028] In this case, the time division multiplexing method can be realized by using a variable coupler as the coupler 11 and selecting the Josephson parametric oscillator 10 to be read out for each time period in the time division multiplexing method. The variable coupler here is a coupler whose operation can be controlled to be turned on and off.

[0029] Furthermore, only some of the multiple Josephson parametric oscillators 10 included in the quantum device 1 may be targets for signal readout. In this case, the Josephson parametric oscillators 10 that are not targets for signal readout may have the same oscillation frequency. For example, consider a case where the quantum device 1 includes four Josephson parametric oscillators 10. The four Josephson parametric oscillators 10 are Josephson parametric oscillators 10A, 10B, 10C, and 10D, and the oscillation frequencies of the four Josephson parametric oscillators 10 are f A , f B , f C , f D Let us assume that.

[0030] When only the four Josephson parametric oscillators 10A and 10B are the targets of signal readout among these four Josephson parametric oscillators 10, the oscillation frequencies of the Josephson parametric oscillators 10C and 10D may be the same. That is, the oscillation frequency f A and the oscillation frequency f B The signal of and are the object of measurement, and the oscillation frequency f C and the oscillation frequency f D If the signal is ignored, f C =f D It may be as follows.

[0031] Here, an arithmetic device using superconducting quantum bits such as quantum device 1 is placed in a dilution refrigerator, and it is required to minimize the number of input and output lines that transmit signals between the inside and outside of the dilution refrigerator. To reduce the number of input and output lines between the inside and outside of a dilution refrigerator, it is possible to transmit signals using frequency division multiplexing, in which the available frequency band of a single transmission medium, such as a cable, is divided into sub-bands, with each sub-band carrying a separate oscillation.

[0032] For example, in quantum device 1, signals are transmitted by frequency division multiplexing, so that input signals and output signals for all Josephson parametric oscillators 10 in all oscillator groups 15 are transmitted over one transmission line 18. As a result, the only signal lines between the inside and outside of the dilution refrigerator are an input line for transmitting an input signal to input port 13 and an output line for transmitting an output signal from output port 14.

[0033] A signal (input signal) inputted by frequency division multiplexing from an input port 13 is transmitted to all Josephson parametric oscillators 10 of the quantum device 1 . Here, circulator 12 k The signal input to port 1 of the circulator 12 k Port 2 to oscillator group 15 kwhere k is an integer such that 1≦k≦N-1.

[0034] Oscillator Group 15 k The frequency of the signal input to the oscillator group 15 k If the oscillation frequency of any of the Josephson parametric oscillators 10 included in the circulator 12 is different, this signal will be reflected theoretically without loss and k The input is input to port 2 of the circulator 12. k The signal input to port 2 of the circulator 12 k The output from port 3 of the circulator 12 k+1 The input is input to port 1 of the

[0035] In this way, each frequency component of the frequency division multiplexed input signal from input port 13 passes through circulator 121, circulator 122, ... and circulator 12 in that order from the input port 13 side, and is input to Josephson parametric oscillator 10 whose oscillation frequency matches that of that frequency component.

[0036] The role of the signal input to the Josephson parametric oscillator 10 (the input signal from the input port 13) can be, for example, a test signal for measuring the reflection coefficient or transmission coefficient of the Josephson parametric oscillator 10, and a drive signal for controlling the Josephson parametric oscillator 10. However, the role of the signal input to the Josephson parametric oscillator 10 is not limited to these.

[0037] All oscillation signals of the Josephson parametric oscillator 10 are output from an output port 14 . Oscillator Group 15 i The oscillation signal of the Josephson parametric oscillator 10 included in i , , Circulator 12 N Then, the air passes through the circulator 12 in order to the output port 14 side, and the air flows through the circulator 12 N The signal is output from port 3 to output port 14.

[0038] Again, Circulator 12 k The oscillation signal input to port 1 of the circulator 12 k Port 2 to oscillator group 15 k Since the oscillation frequencies of all the Josephson parametric oscillators 10 are different from each other, the oscillation signal is input to the oscillator group 15. k The Josephson parametric oscillator 10 is reflected by the circulator 12. k The input is input to port 2 of the circulator 12. k The oscillation signal input to port 2 of the circulator 12 k The output from port 3 of the circulator 12 k+1 The input is input to port 1 of the

[0039] On the other hand, oscillator group 15 l The oscillation signal of the Josephson parametric oscillator 10 included in l By blocking signals from port 2 to port 1, the oscillator group 15 on the input port 13 side is switched from the oscillator group 151 to the oscillator group 15 l-1 Here, l is an integer such that 2≦l≦N.

[0040] The quantum device 1 can reduce the influence of crosstalk between the Josephson parametric oscillators 10. Here, crosstalk between the Josephson parametric oscillators 10 refers to an oscillation signal of one Josephson parametric oscillator 10 being input to another Josephson parametric oscillator. Specifically, the oscillator group 15 k+1 The oscillation signal of the Josephson parametric oscillator 10 is supplied from the oscillator group 151 to the oscillator group 15 k The transmission of the received signal is suppressed until the time of transmission.

[0041] As a result, in the quantum device 1, the oscillator group 15 k+1 From Oscillator Group 15 N The oscillation signals of the Josephson parametric oscillators 10 up to kThe oscillator group 15 is generated by injecting the Josephson parametric oscillator 10 k Therefore, it is possible to prevent or reduce the degradation of the readout fidelity of the Josephson parametric oscillator 10.

[0042] For example, as described above, it is expected that the degree of freedom in the operating parameter values ​​for reducing the influence of the incident signals will be increased by reducing the number of incident signals from other Josephson parametric oscillators 10. This increases the degree of freedom in the combination of operating parameter values ​​for the entire Josephson parametric oscillator 10, and it is expected that the influence of the incident signals can be reduced with higher accuracy by adopting a more suitable combination of operating parameter values.

[0043] A non-limiting indicator of the readout fidelity of the Josephson parametric oscillator 10 may be the probability of correctly identifying the quantum bit state of the Josephson parametric oscillator 10 by measuring the oscillation signal of the Josephson parametric oscillator 10 .

[0044] Furthermore, in the quantum device 1, the effects of crosstalk can be reduced without using an element that limits the passband, such as a bandpass filter, and in this respect, the frequency tunability of the Josephson parametric oscillator 10 can be utilized.

[0045] For example, when quantum annealing is performed using the quantum device 1, the adjustment range for adjusting the operating parameter values ​​is widened by ensuring the frequency tunability of the Josephson parametric oscillator 10. This makes it possible to adjust the operating parameter values ​​relatively easily, and it is expected that the operating parameter values ​​can be appropriately set, enabling quantum annealing to be performed with relatively high accuracy.

[0046] Alternatively, it is possible to change the oscillation frequency when controlling the Josephson parametric oscillator 10. In this case, it is sufficient that frequency multiplicity is obtained when the oscillation signal is measured, and it is not necessary that frequency multiplicity is obtained before the measurement.

[0047] As described above, the quantum device 1 includes a plurality of oscillator groups 15, a plurality of circulators 12, and a transmission path 18 common to the plurality of circulators 12. Each of the plurality of oscillator groups 15 includes one or more Josephson parametric oscillators 10. One or more Josephson parametric oscillators 10 included in one oscillator group 15 are connected to one port (port 2) of one circulator 12 common to the one or more Josephson parametric oscillators 10. Each of the plurality of circulators 12 is arranged on the transmission path 18 so as to transmit a signal from the input port 13 side of the transmission path 18 to the oscillator group 15 side, transmit a signal from the oscillator group 15 side to the output port 14 side of the transmission path 18, and block signals from the output port 14 side to the oscillator group 15 side and from the oscillator group 15 side to the input port 13 side.

[0048] The quantum device 1 can reduce the influence of crosstalk between the Josephson parametric oscillators 10 and utilize the frequency tunability of the oscillators.

[0049] Moreover, the frequency characteristics of all the Josephson parametric oscillators 10 included in all the oscillator groups 15 are different from each other. According to the quantum device 1, input and output signals of all Josephson parametric oscillators 10 included in all oscillator groups 15 can be transmitted by frequency division multiplexing.

[0050] <Second embodiment> Fig. 4 is a diagram showing an example of the configuration of a quantum device according to the second embodiment. In the configuration shown in Fig. 4, the quantum device 2 includes N Josephson parametric oscillators 10, N couplers 11, N circulators 12, and one transmission line 18. Ends of the transmission line 18 are used as an input port 13 and an output port 14.

[0051] 4, parts having similar functions to those of the parts in FIG. 1 or 2 are denoted by the same reference numerals (10, 11, 12, 121, 122, . . . , 12 N , 13, 14, 18) and detailed explanations will be omitted here. In the example of FIG. 4, the circulators 12 and the couplers 11 are arranged in one-to-one correspondence. i and coupler 11 i That is, in the quantum device 2, only one pair of a coupler 11 and a Josephson parametric oscillator 10 is connected to one circulator 12.

[0052] In other respects, quantum device 2 is similar to quantum device 1. The configuration of quantum device 2 can be considered to be the same as that of quantum device 1, except that one oscillator group 15 includes only one pair of a coupler 11 and a Josephson parametric oscillator 10.

[0053] In the configuration of FIG. 4, when N Josephson parametric oscillators 10 are to be distinguished, the Josephson parametric oscillator 101, the Josephson parametric oscillator 102, . . . , the Josephson parametric oscillator 10 N When distinguishing the N number of couplers 11, they are expressed as coupler 111, coupler 112, . . . , coupler 11 N It can also be written as:

[0054] As described above, in the quantum device 2, one circulator 12 and one Josephson parametric oscillator 10 are connected. As with quantum device 1, quantum device 2 can reduce the effects of crosstalk between Josephson parametric oscillators 10 and utilize the frequency tunability of the oscillators.

[0055] Furthermore, compared to the quantum device 1, the quantum device 2 is said to be able to reduce the influence of crosstalk between the Josephson parametric oscillators 10 included in the oscillator group 15 in the quantum device 1. In this respect, quantum device 2 is expected to be able to reduce the influence of crosstalk between Josephson parametric oscillators 10 even more than quantum device 1. On the other hand, in the quantum device 1, in comparison with the quantum device 2, the number of circulators 12 relative to the number of Josephson parametric oscillators 10 can be smaller.

[0056] <Third embodiment> Fig. 5 is a diagram showing an example of the configuration of a quantum device according to the third embodiment. In the configuration shown in Fig. 5, the quantum device 3 includes N oscillator groups 15, N circulators 12, N-1 isolators 17, and one transmission line 18. Ends of the transmission line 18 are used as an input port 13 and an output port 14. 5, parts having similar functions to those of the parts in FIG. 1 are designated by the same reference numerals (12, 121, 122, . . . , 12 N , 13, 14, 15, 151, 152, . . . , 15 N , 18) and a detailed explanation will be omitted here.

[0057] The quantum device 3 differs from the quantum device 1 in that, for each pair of circulators 12 adjacent to each other in the transmission line 18, an isolator 17 is provided between the pair of circulators 12. k Port 3 of the isolator 17 k Via Circulator 12 k+1 is connected to port 1 of the In other respects, quantum device 3 is similar to quantum device 1. When distinguishing between N-1 isolators 17, isolator 171, isolator 172, ..., isolator 17 N-1 , can also be written as

[0058] Isolator 17 transmits signals in only one direction. In quantum device 3, isolator 17 is oriented so as to transmit signals from input port 13 to output port 14, but block signals from output port 14 to input port 13. Note that, although Figure 5 shows an example in which one isolator 17 is provided for each pair of adjacent circulators 12 in the transmission path 18, isolators 17 may be provided only for some of the pairs of adjacent circulators 12 in the transmission path 18.

[0059] As described above, the isolator 17 is provided between at least a pair of adjacent circulators 12 in the transmission path 18, and transmits signals from the input port 13 side to the output port 14 side, and blocks signals from the output port 14 side to the input port 13 side. As with quantum device 1, quantum device 3 can reduce the effects of crosstalk between Josephson parametric oscillators 10 and take advantage of the frequency tunability of the oscillators. Furthermore, compared to the quantum device 1, the quantum device 3 is expected to be able to further reduce the influence of crosstalk between the Josephson parametric oscillators 10 because the quantum device 3 is provided with the isolator 17.

[0060] <Fourth embodiment> FIG. 6 is a diagram illustrating an example of the configuration of a quantum device according to the fourth embodiment. 6, the quantum device 2 includes N Josephson parametric oscillators 10, N couplers 11, N circulators 12, N-1 isolators 17, and one transmission line 18. Ends of the transmission line 18 are used as an input port 13 and an output port 14.

[0061] 6, parts having similar functions to those of the parts in FIG. 4 are designated by the same reference numerals (10, 101, 102, . . . , 10 N , 11, 111, 112, . . . , 11 N , 12, 121, 122, . . . , 12 N , 13, 14, 18) and detailed explanations will be omitted here.

[0062] The quantum device 4 differs from the quantum device 2 in that, for each pair of circulators 12 adjacent to each other in the transmission line 18, an isolator 17 is provided between the pair of circulators 12. k Port 3 of the isolator 17 k Via Circulator 12 k+1 is connected to port 1 of the Otherwise, quantum device 4 is similar to quantum device 2.

[0063] The isolator 17 is the same as that in the quantum device 3, and is given the same reference numeral (17) as in FIG. 5, and a detailed description thereof will be omitted here. When distinguishing between N-1 isolators 17, isolator 171, isolator 172, ..., isolator 17 N-1 , can also be written as

[0064] In addition, while Figure 6 shows an example in which one isolator 17 is provided for each pair of adjacent circulators 12 in the transmission path 18, isolators 17 may be provided only for some of the pairs of adjacent circulators 12 in the transmission path 18.

[0065] As described above, in the quantum device 4, one circulator 12 and one Josephson parametric oscillator 10 are connected. As with quantum device 2, quantum device 4 can reduce the effects of crosstalk between Josephson parametric oscillators 10 and take advantage of the frequency tunability of the oscillators. Furthermore, compared to the quantum device 2, the quantum device 4 is expected to be able to further reduce the influence of crosstalk between the Josephson parametric oscillators 10 due to the inclusion of the isolator 17.

[0066] <Fifth embodiment> It has been found that the magnitude of the effect of a signal incident on a Josephson parametric oscillator on the Josephson parametric oscillator depends on the oscillation frequency of the Josephson parametric oscillator and the frequency of the incident signal.

[0067] From this, it is expected that when transmitting input / output signals to multiple Josephson parametric oscillators using the frequency division multiplexing method, the effects of crosstalk between the Josephson parametric oscillators can be reduced by adjusting the oscillation frequencies of the Josephson parametric oscillators.

[0068] In the fifth embodiment, an example of adjusting the oscillation frequency of the Josephson parametric oscillator 10 in the first embodiment will be described. The quantum device in the fifth embodiment is similar to that in the first embodiment, except that the oscillation frequency of the Josephson parametric oscillator is set based on a specific condition. The fifth embodiment will also be described with reference to FIGS. 1 to 3.

[0069] The upper limit of the frequency of the incident signal to which the Josephson parametric oscillator is sensitive, f inf_max can be expressed as equation (1).

[0070]

number

[0071] f pump f represents the frequency of the pump signal input to the Josephson parametric oscillator receiving the signal. pump / 2 can be roughly equated to the oscillation frequency of a Josephson parametric oscillator. The lower limit of the frequency of the incident signal to which the Josephson parametric oscillator is sensitive, f inf_min can be expressed as equation (2).

[0072]

number

[0073] Here, × represents scalar multiplication. K represents the Kerr coefficient. The Kerr coefficient K is a coefficient that represents the Kerr nonlinearity of a Josephson parametric oscillator, which is a nonlinear resonator, and is generally K<0. α represents the coherent state amplitude, which is an eigenvalue for the annihilation operator when the quantum state of the Josephson parametric oscillator is regarded as a coherent state. The coefficient c is a constant that takes a value from 1 to 4.

[0074] The lower limit of the frequency of the incident signal to which the Josephson parametric oscillator is susceptible, f inf_min to upper limit f inf_max The range up to is also referred to as the frequency range to which the Josephson parametric oscillator is susceptible.

[0075] The frequency of the incident signal to which the Josephson parametric oscillator is susceptible is 2×K×α, expressed as a relative value based on the oscillation frequency of the Josephson parametric oscillator. 2 ×c to 0, where 2×K×α 2 ×c<0. 2×K×α2 ×c is generally in the range of -800 megahertz (MHz) to -20 megahertz (MHz), typically -100 megahertz. This is the product Kα 2 can be approximated by −1 times the intensity of the pump signal input to the Josephson parametric oscillator, and is generally expressed as Kα 2 This is because it has a value of O(-10) megahertz.

[0076] In the quantum device 1, the effect of crosstalk between the Josephson parametric oscillators 10 can be further reduced by ensuring that the frequency of the oscillation signal of another Josephson parametric oscillator that is input to the Josephson parametric oscillator 10 is not included in the frequency range to which the Josephson parametric oscillator 10 receiving the input signal is susceptible.

[0077] Therefore, the oscillation frequency of the Josephson parametric oscillator 10 is set so as to satisfy the following conditions (1) and (2). (1) For any combination of two Josephson parametric oscillators 10 included in the same oscillator group 15, the magnitude of the difference in oscillation frequency between the two Josephson parametric oscillators 10 is |2×K×α 2 ×c| or more. That is, the magnitude of the difference in oscillation frequency between any Josephson parametric oscillator 10 in any oscillator group 15 and any other Josephson parametric oscillator 10 included in the oscillator group 15 is greater than or equal to |2×K×α 2 × c|, where || represents the absolute value.

[0078] (2) For any combination of two Josephson parametric oscillators 10 included in different oscillator groups 15, the oscillation frequency of the Josephson parametric oscillator 10 included in the oscillator group 15 on the input port 13 side of the two Josephson parametric oscillators 10 is outside the frequency range determined as the range to which the Josephson parametric oscillator 10 included in the oscillator group 15 on the output port 14 side is easily influenced. l-1 The oscillation frequency of any of the Josephson parametric oscillators 10 included in the oscillator group 15 l As described above, l is an integer satisfying 2≦l≦N, and N is an integer satisfying N≧2 indicating the number of oscillator groups 15.

[0079] Fig. 7 is a diagram showing an example of the oscillation frequency of the Josephson parametric oscillator 10 in the quantum device 1. The vertical axis of the graph in Fig. 7 represents frequency, and the horizontal axis shows the oscillator group 15. In FIG. 7, a Josephson parametric oscillator 10 i_j The oscillation frequency of f 1_i_j As above, i is an integer such that 1≦i≦N. j is an integer such that 1≦j≦M. i is an integer. i is the oscillator group 15 i M indicates the number of Josephson parametric oscillators 10 included in the i It is an integer greater than or equal to 1.

[0080] In the example of Figure 7, f 1_1_j ≧f 1_2_j ≧ ≧ f 1_N_j In addition, f 1_N_j and f 1_1_j+1 The magnitude of the difference between fd j fd j ≧|2×K×α 2 ×c|. fd1, fd2, ...fd N-1 The values ​​may be the same or different.

[0081] In this way, in the example of FIG. 7, the oscillation frequency of the Josephson parametric oscillator 10 included in the oscillator group 15 on the input port 13 side is greater (higher) than the oscillation frequency of the Josephson parametric oscillator 10 on the output port 14 side, or is lower than the oscillation frequency of the Josephson parametric oscillator 10 on the output port 14 side by |2×K×α 2 ×c| or smaller (lower).

[0082] In the example of FIG. 7, the magnitude of the difference in oscillation frequency between the Josephson parametric oscillators 10 included in the same oscillator group 15 is |2×K×α 2 ×c| or more, which satisfies the above condition (1). f inf_min From f inf_max The width of the range is |2×K×α 2 ×c| corresponds to an example of the width of the range defined as the frequency range to which an oscillator is susceptible.

[0083] In addition, in the example of FIG. 7, the oscillation frequency of the Josephson parametric oscillator 10 included in the oscillator group 15 on the input port 13 side is outside the frequency range to which the Josephson parametric oscillator 10 included in the oscillator group 15 on the output port 14 side is easily affected, and the above condition (2) is satisfied.

[0084] As described above, at least one oscillator group 15 includes a plurality of Josephson parametric oscillators 10. For any combination of two Josephson parametric oscillators 10 included in the same oscillator group 15, the magnitude of the difference in the oscillation frequencies of the two Josephson parametric oscillators 10 is equal to or greater than the width of the frequency range to which the Josephson parametric oscillators 10 are susceptible, i.e., |2×K×α 2 The oscillation frequency of each Josephson parametric oscillator 10 is set to be greater than or equal to |xc|. According to the quantum device 1, the influence of crosstalk between the Josephson parametric oscillators 10 included in the same oscillator group 15 can be reduced.

[0085] Furthermore, for any combination of two Josephson parametric oscillators 10 included in different oscillator groups 15, the oscillation frequency of each Josephson parametric oscillator 10 is set so that the oscillation frequency of the Josephson parametric oscillator 10 included in the oscillator group 15 on the input port 13 side of the two Josephson parametric oscillators 10 is outside the frequency range defined as the range to which the Josephson parametric oscillator 10 included in the oscillator group 15 on the output port 14 side is easily influenced. According to the quantum device 1, the influence of crosstalk between the Josephson parametric oscillators 10 included in different oscillator groups 15 can be reduced.

[0086] In addition, the upper limit f of the frequency range in which the Josephson parametric oscillator 10 is susceptible inf_max is the oscillation frequency f of the Josephson parametric oscillator 10. pump It is set at / 2. According to the quantum device 1, the influence of crosstalk between Josephson parametric oscillators 10 can be reduced based on the knowledge that the upper limit of the frequency range to which the Josephson parametric oscillator 10 is susceptible is the oscillation frequency of that Josephson parametric oscillator 10.

[0087] The lower limit of the frequency range in which the Josephson parametric oscillator 10 is susceptible is f inf_min is the oscillation frequency f of the Josephson parametric oscillator 10. pump / 2, the Kerr coefficient K, and the coherent state amplitude α. According to the quantum device 1, the influence of crosstalk between Josephson parametric oscillators 10 can be reduced based on the knowledge that the lower limit of the frequency range to which the Josephson parametric oscillator 10 is susceptible depends on the oscillation frequency, Kerr coefficient, and coherent state amplitude of the Josephson parametric oscillator 10.

[0088] The lower limit of the frequency range f to which the Josephson parametric oscillator 10 is susceptible inf_min may be defined as a frequency obtained by subtracting a value within the range of 20 megahertz to 800 megahertz from the oscillation frequency of the Josephson parametric oscillator 10. The lower limit of the frequency range in which the Josephson parametric oscillator 10 is susceptible is f inf_min may be defined as the oscillation frequency of the Josephson parametric oscillator 10 minus 100 megahertz.

[0089] In the fifth embodiment, the quantum device 3 according to the third embodiment may be used in place of the quantum device 1 according to the first embodiment. In this case, too, the oscillation frequency of the Josephson parametric oscillator 10 can be set in the same way as when the quantum device 1 is used in the fifth embodiment, and the same effects as when the quantum device 1 is used in the fifth embodiment can be obtained.

[0090] Sixth embodiment In the sixth embodiment, an example of adjusting the oscillation frequency of the Josephson parametric oscillator 10 in the second embodiment will be described. The quantum device in the sixth embodiment is similar to that in the second embodiment, except that the oscillation frequency of the Josephson parametric oscillator is set based on specific conditions. The sixth embodiment will also be described with reference to FIGS. 1 to 4.

[0091] As in the second embodiment, the configuration of the quantum device 2 according to the sixth embodiment can be understood as a configuration in which the quantum device 1 according to the fifth embodiment includes only one pair of a coupler 11 and a Josephson parametric oscillator 10 in one oscillator group 15. Therefore, in the sixth embodiment, the oscillation frequency of the Josephson parametric oscillator 10 is set so that the condition (2) of the conditions (1) and (2) described in the fifth embodiment is satisfied. Regarding the condition (1), since the number of the Josephson parametric oscillator 10 included in one oscillator group 15 is only one in the sixth embodiment, the condition (1) can be considered to be always satisfied.

[0092] Fig. 8 is a diagram showing an example of the oscillation frequency of the Josephson parametric oscillator 10 in the quantum device 2. The vertical axis of the graph in Fig. 8 represents frequency, and the horizontal axis shows the oscillator group 15. In FIG. 8, a Josephson parametric oscillator 10 i The oscillation frequency of f 2_i As described above, i is an integer satisfying 1≦i≦N, and N is an integer satisfying N≧2 indicating the number of oscillator groups 15.

[0093] In the example of Figure 8, f 2_1 ≧f 2_2 ≧ ≧ f 2_N It is as follows. Thus, in the example of FIG. 8, the oscillation frequency of the Josephson parametric oscillator 10 on the input port 13 side is greater (higher) than the oscillation frequency of the Josephson parametric oscillator 10 on the output port 14 side. In the example of FIG. 8, the oscillation frequency of the Josephson parametric oscillator 10 on the input port 13 side is outside the frequency range in which the Josephson parametric oscillator 10 on the output port 14 side is easily affected, and the above condition (2) is satisfied.

[0094] The Josephson parametric oscillator 10 on the input port 13 side can be regarded as the Josephson parametric oscillator 10 included in the oscillator group 15 on the input port 13 side. The Josephson parametric oscillator 10 on the output port 14 side can be regarded as the Josephson parametric oscillator 10 included in the oscillator group 15 on the output port 14 side.

[0095] In the sixth embodiment, the same effects as in the fifth embodiment can be obtained. Moreover, in the sixth embodiment, the oscillation frequency of the Josephson parametric oscillator 10 on the input port 13 side may be set higher than the oscillation frequency of the Josephson parametric oscillator 10 on the output port 14 side. In this respect, in the sixth embodiment, the oscillation frequency of the Josephson parametric oscillator 10 can be determined relatively easily.

[0096] In the sixth embodiment, the quantum device 4 according to the fourth embodiment may be used in place of the quantum device 2 according to the second embodiment. In this case, too, the oscillation frequency of the Josephson parametric oscillator 10 can be set in the same way as when the quantum device 2 is used in the sixth embodiment, and the same effects as when the quantum device 2 is used in the sixth embodiment can be obtained.

[0097] Seventh embodiment In the seventh embodiment, an example of the configuration of a quantum computing system including a quantum device and a control device that controls the quantum device will be described. 9 is a diagram illustrating an example of the configuration of a quantum computing system according to the seventh embodiment. In the configuration illustrated in FIG. 9, a quantum computing system 100 includes a quantum device 110 and a control device 120.

[0098] Quantum computing system 100 is a system that performs calculations using quantum devices. Quantum device 110 is a quantum device in which the flow of signals between oscillators is limited to one-way flow using a circulator. As the oscillator of quantum device 110, a Josephson parametric oscillator may be used. As quantum device 110, any one of quantum device 1, quantum device 2, quantum device 3, or quantum device 4 may be used.

[0099] The control device 120 controls the quantum device 110 to perform calculations. In particular, the control device 120 controls the oscillator of the quantum device 110 by generating and transmitting a control signal for the oscillator. The control device 120 may be configured using a computer. The control device 120 may control the oscillation frequency of the oscillator, similarly to the fifth or sixth embodiment.

[0100] (Experimental Example) An experiment was conducted to confirm that the configuration using a circulator and an isolator reduces crosstalk at the input port side. Fig. 10 is a diagram showing an example of the configuration of a quantum device used in an experiment. In the configuration shown in Fig. 10, a quantum device 5 includes a quantum chip 40, two coaxial cables 44, two circulators 12, one isolator 17, and two measuring instruments 45.

[0101] The quantum chip 40 has two Josephson parametric oscillators 10 , two capacitive couplings 41 , two transmission lines 42 , and two signal ports 43 . The two Josephson parametric oscillators 10 are also referred to as a first Josephson parametric oscillator 101 and a second Josephson parametric oscillator 102. The two capacitive couplings 41 are also referred to as a first capacitive coupling 411 and a second capacitive coupling 412. The two transmission paths 42 are also referred to as a first transmission path 421 and a second transmission path 422. The two signal ports 43 are also referred to as a first signal port 431 and a second signal port 432.

[0102] The first Josephson parametric oscillator 101 is connected to a first signal port 431 via a first capacitive coupling 411 and a first transmission line 421. The second Josephson parametric oscillator 102 is connected to a second signal port 432 via a second capacitive coupling 412 and a second transmission line 422.

[0103] The two coaxial cables 44 are also referred to as a first coaxial cable 441 and a second coaxial cable 442. The two circulators 12 are also referred to as a first circulator 121 and a second circulator 122. The two measuring instruments 45 are also referred to as a first measuring instrument 451 and a second measuring instrument 452.

[0104] The first signal port 431 is connected to the first circulator 121 via a first coaxial cable 441. The second signal port 432 is connected to the second circulator 122 via a second coaxial cable 442. Port 1 of the first circulator 121 is connected to a first measuring instrument 451 , port 2 is connected to a first coaxial cable 441 , and port 3 is connected to the isolator 17 .

[0105] Port 1 of the second circulator 122 is connected to the isolator 17 , port 2 is connected to a second coaxial cable 442 , and port 3 is connected to a second measuring instrument 452 . The isolator 17 is oriented so as to transmit a signal from the first circulator 121 to the second circulator 122 and block the signal from the second circulator 122 to the first circulator 121. The quantum chip 40 is kept at a low temperature using a dilution refrigerator.

[0106] In the quantum device 5, it is possible to reduce crosstalk between the two Josephson parametric oscillators 10. Specifically, the transmission of the oscillation signal of the second Josephson parametric oscillator 102 to the first Josephson parametric oscillator 101 is suppressed. This makes it possible in the quantum device 5 to prevent or reduce a decrease in the readout fidelity of the first Josephson parametric oscillator 101 caused by the incidence of the oscillation signal of the second Josephson parametric oscillator 102. Furthermore, the quantum device 5 can reduce crosstalk without using an element that limits the passband, such as a bandpass filter, and in this respect, the frequency tunability of the Josephson parametric oscillator 10 can be utilized.

[0107] In an experiment using the quantum device 5, a change in read fidelity of the first Josephson parametric oscillator 101 was measured when the second Josephson parametric oscillator 102 was outputting an oscillation signal and when it was not outputting an oscillation signal. Also, a change in read fidelity of the second Josephson parametric oscillator 102 was measured when the first Josephson parametric oscillator 101 was outputting an oscillation signal and when it was not outputting an oscillation signal. As a measure of readout fidelity, we used the probability of correctly identifying the quantum bit state of the Josephson parametric oscillator 10 by measuring the oscillation signal.

[0108] Experiments have shown that the former (change in readout fidelity of the first Josephson parametric oscillator 101 when the second Josephson parametric oscillator 102 is outputting an oscillation signal and when it is not outputting an oscillation signal) is smaller than the latter (change in readout fidelity of the second Josephson parametric oscillator 102 when the first Josephson parametric oscillator 101 is outputting an oscillation signal and when it is not outputting an oscillation signal). This experimental result can be evaluated as being able to prevent or reduce the degradation of the readout fidelity of the first Josephson parametric oscillator 101 due to the incidence of the oscillation signal of the second Josephson parametric oscillator 102.

[0109] In addition, we conducted an experiment using a numerical simulation based on quantum mechanics to investigate the relationship between the frequency of the signal incident on the Josephson parametric oscillator and the degree of its effect on the Josephson parametric oscillator. In the experiment, we investigated the relationship between the frequency and power (intensity) of the signal incident on the Josephson parametric oscillator and the readout fidelity of the Josephson parametric oscillator.

[0110] In the experiment, the Kerr coefficient K=-12 MHz and the coherent state amplitude α=1.1. In addition, the detuning of the incident signal was set in the simulator as the frequency setting of the incident signal. The detuning Δ of the incident signal is expressed as in Equation (3).

[0111]

number

[0112] f input f denotes the frequency of the incident signal. pump denotes the frequency of the pump signal input to the Josephson parametric oscillator. In addition, as the readout fidelity of the Josephson parametric oscillator, the probability of correctly identifying the quantum bit state of the Josephson parametric oscillator 10 by measuring the oscillation signal of the Josephson parametric oscillator 10 was calculated. Specifically, the total probability was calculated as the probability that the bit value indicated by the Josephson parametric oscillator is 0 and the bit value readable by measuring the state of the Josephson parametric oscillator is 0, and the probability that the bit value indicated by the Josephson parametric oscillator is 1 and the bit value readable by measuring the state of the Josephson parametric oscillator is 1.

[0113] 11 is a diagram showing an example of the relationship between the detuning and power of the signal incident on the Josephson parametric oscillator and the readout fidelity of the Josephson parametric oscillator, which is obtained experimentally. The horizontal axis of the graph in Figure 11 represents the detuning of the incident signal. The horizontal axis is in megahertz. The vertical axis represents the power of the incident signal. The vertical axis is in decibel milliwatts (dBm).

[0114] In addition, the readout fidelity of the Josephson parametric oscillator is shown in gray scale in Figure 11. The brighter (whiter) parts of the graph indicate higher readout fidelity, and the darker (blacker) parts indicate lower readout fidelity. Line L11 indicates the contour of read fidelity=0.95.

[0115] For example, assuming that the power of the oscillation signal of the Josephson parametric oscillator is within the range of -130 dBmW to -120 dBmW, when the detuning Δ is 0 or more, the readout fidelity is almost always 95% or more. In addition, assuming that the power of the oscillation signal of the Josephson parametric oscillator is within the range of -130 dBmW to -120 dBmW, when the detuning Δ is -1000 MHz or less, the readout fidelity is almost always 95% or more. From this, it is conceivable to define the frequency range in which the Josephson parametric oscillator is susceptible to influence as the range from the oscillation frequency -100 megahertz up to the oscillation frequency.

[0116] <Eighth embodiment> Fig. 12 is a diagram showing an example of the configuration of a quantum device according to the eighth embodiment. In the configuration shown in Fig. 12, a quantum device 610 includes a plurality of oscillator groups 611, a plurality of circulators 613, and a transmission line 614 common to the plurality of circulators 613. Each of the plurality of oscillator groups 611 includes one or more oscillators 612 having frequency tunability.

[0117] One or more oscillators 612 included in one oscillator group 611 are connected to one port of one circulator 613 common to the one or more oscillators 612. Each of the multiple circulators 613 is arranged on the transmission path 614 so as to transmit a signal from a first end of the transmission path 614 to the oscillator group 611 side, transmit a signal from the oscillator group 611 side to a second end of the transmission path, and block signals from the second end to the oscillator group 611 side and from the oscillator group 611 side to the first end side.

[0118] The quantum device 610 can reduce crosstalk between the oscillators 612. Specifically, the transmission of an oscillation signal of an oscillator 612 in a certain oscillator group 611 to an oscillator group 611 on the first end side of the certain oscillator group 611 is suppressed. Furthermore, in quantum device 610, crosstalk can be reduced without using an element that limits the passband, such as a bandpass filter, and in this respect, the frequency tunability of oscillator 612 can be utilized. In this way, quantum device 610 can reduce crosstalk between oscillators 612 and utilize the frequency tunability of oscillators 612.

[0119] <Ninth embodiment> Fig. 13 is a diagram showing an example of a process procedure in an oscillation frequency setting method according to the 9th embodiment. The oscillation frequency setting method shown in Fig. 13 includes setting an oscillation frequency (step S611).

[0120] In a ninth embodiment, the quantum device includes a plurality of oscillator groups, a plurality of circulators, and a transmission line common to the plurality of circulators. Each of the plurality of oscillator groups includes one or more oscillators having frequency tunability. One or more oscillators included in one oscillator group are connected to one port of one circulator common to the one or more oscillators. Each of the plurality of circulators is arranged in the transmission line so as to transmit a signal from a first end side of the transmission line to the oscillator group side, transmit a signal from the oscillator group side to a second end side of the transmission line, and block signals from the second end side to the oscillator group side and from the oscillator group side to the first end side.

[0121] In setting the oscillation frequency (step S611), a control device that controls the quantum device sets the oscillation frequency of each oscillator for any combination of two oscillators included in different oscillator groups so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range defined as a range to which the oscillator included in the oscillator group on the second end side is easily influenced. According to the oscillation frequency setting method shown in FIG. 13, it is possible to reduce the influence of crosstalk between oscillators included in different oscillator groups.

[0122] FIG. 14 is a schematic block diagram illustrating an example configuration of a computer according to at least one embodiment. In the configuration shown in FIG. 14, a computer 700 includes a CPU (Central Processing Unit) 710, a main memory device 720, an auxiliary memory device 730, an interface 740, and a non-volatile recording medium 750.

[0123] The above-described control device 120 or a part thereof may be implemented in a computer 700. In this case, the operation of the control device 120 is stored in the form of a program in an auxiliary storage device 730. The CPU 710 reads the program from the auxiliary storage device 730, loads it in the main storage device 720, and executes the above-described processing in accordance with the program. Furthermore, the CPU 710 allocates a storage area in the main memory device 720 for the control device 120 to perform processing in accordance with the program. Communication between the control device 120 and other devices is performed by the interface 740 having a communication function and performing communication under the control of the CPU 710. Interaction between the control device 120 and a user is performed by the interface 740 having a display device and an input device, displaying various images under the control of the CPU 710, and accepting user operations.

[0124] Any one or more of the above-mentioned programs may be recorded in non-volatile recording medium 750. In this case, interface 740 may read the program from non-volatile recording medium 750. Then, CPU 710 may directly execute the program read by interface 740, or may temporarily store the program in main storage device 720 or auxiliary storage device 730 and execute it.

[0125] Note that a program for executing the processes or a part of the processes performed by the control device 120 may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform the processes of each part. Note that the term "computer system" here includes the OS (Operating System) and hardware such as peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs (Read Only Memory), and CD-ROMs (Compact Disc Read Only Memory), as well as storage devices such as hard disks built into computer systems. The above-mentioned program may be for realizing part of the above-mentioned functions, or may be capable of realizing the above-mentioned functions in combination with a program already recorded in the computer system.

[0126] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included.

[0127] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes.

[0128] (Appendix 1) The present invention comprises a plurality of oscillator groups, a plurality of circulators, and a transmission line common to the plurality of circulators, Each of the plurality of oscillator groups includes one or more oscillators having frequency tunability; One or more oscillators included in one oscillator group are connected to one port of one circulator common to the one or more oscillators; each of the plurality of circulators is disposed on the transmission path so as to transmit a signal from a first end of the transmission path to the oscillator group and transmit a signal from the oscillator group to a second end of the transmission path, and to block signals from the second end to the oscillator group and from the oscillator group to the first end. Quantum devices.

[0129] (Appendix 2) The oscillation frequencies of all the oscillators included in all the oscillator groups are different from each other. 2. The quantum device of claim 1.

[0130] (Appendix 3) an isolator provided between at least a pair of adjacent circulators in the transmission path, for transmitting a signal from the first end side to the second end side and blocking a signal from the second end side to the first end side; 3. The quantum device of claim 1 or 2, further comprising:

[0131] (Appendix 4) One of the circulators and one of the oscillators are connected. 4. A quantum device according to any one of claims 1 to 3.

[0132] (Appendix 5) At least one of the oscillator groups includes a plurality of the oscillators; For any combination of two oscillators included in the same oscillator group, the oscillation frequency of each oscillator is set so that the magnitude of the difference between the oscillation frequencies of the two oscillators is greater than or equal to the width of a frequency range defined as the frequency range to which the oscillator is susceptible. 4. A quantum device according to any one of claims 1 to 3.

[0133] (Appendix 6) For any combination of two oscillators included in different oscillator groups, the oscillation frequency of each oscillator is set so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range determined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced. 6. A quantum device according to any one of claims 1 to 5.

[0134] (Appendix 7) The upper limit of the frequency range to which the oscillator is susceptible is determined to be the oscillation frequency of the oscillator. 7. The quantum device of claim 6.

[0135] (Appendix 8) The lower limit of the frequency range to which the oscillator is susceptible is determined to be a frequency calculated based on the oscillation frequency of the oscillator, the Kerr coefficient, and the coherent state amplitude. 8. The quantum device of claim 6 or 7.

[0136] (Appendix 9) The lower limit of the frequency range to which the oscillator is susceptible is defined as a frequency obtained by subtracting a value within the range of 20 MHz to 800 MHz from the oscillation frequency of the oscillator. 9. A quantum device according to any one of claims 6 to 8.

[0137] (Appendix 10) The lower limit of the frequency range to which the oscillator is susceptible is defined as the oscillation frequency of the oscillator minus 100 megahertz. 10. The quantum device of claim 9.

[0138] (Appendix 11) a control device for controlling a quantum device, comprising: a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency tunability, at least one of the oscillator groups comprising a plurality of the oscillators, one or more oscillators included in one oscillator group being connected to one port of one circulator common to the one or more oscillators, each of the plurality of circulators transmitting a signal from a first end side of the transmission path to the oscillator group side, transmitting a signal from the oscillator group side to a second end side of the transmission path, and blocking signals from the second end side to the oscillator group side and from the oscillator group side to the first end side; For any combination of two oscillators included in the same oscillator group, the oscillation frequency of each oscillator is set so that the magnitude of the difference between the oscillation frequencies of the two oscillators is greater than or equal to the width of a frequency range defined as the frequency range to which the oscillator is susceptible. The oscillation frequency setting method includes:

[0139] (Appendix 12) a control device for controlling a quantum device, comprising: a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency tunability, the one or more oscillators included in one oscillator group being connected to one port of one circulator common to the one or more oscillators, each of the plurality of circulators transmitting a signal from a first end side of the transmission path to the oscillator group side and transmitting a signal from the oscillator group side to a second end side of the transmission path, and blocking signals from the second end side to the oscillator group side and from the oscillator group side to the first end side; For any combination of two oscillators included in different oscillator groups, the oscillation frequency of each oscillator is set so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range determined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced. The oscillation frequency setting method includes:

[0140] (Appendix 13) a computer that controls a quantum device comprising: a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency tunability, at least one of the oscillator groups comprising a plurality of the oscillators, one or more oscillators included in one oscillator group being connected to one port of one circulator common to the one or more oscillators, each of the plurality of circulators transmitting a signal from a first end side of the transmission path to the oscillator group side, transmitting a signal from the oscillator group side to a second end side of the transmission path, and blocking signals from the second end side to the oscillator group side and from the oscillator group side to the first end side; For any combination of two oscillators included in the same oscillator group, the oscillation frequency of each oscillator is set so that the magnitude of the difference between the oscillation frequencies of the two oscillators is greater than or equal to the width of a frequency range defined as the frequency range to which the oscillator is susceptible. A program for executing the above.

[0141] (Appendix 14) a computer that controls a quantum device comprising: a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency tunability, one or more oscillators included in one oscillator group being connected to one port of one circulator common to the one or more oscillators, each of the plurality of circulators transmitting a signal from a first end side of the transmission path to the oscillator group side, transmitting a signal from the oscillator group side to a second end side of the transmission path, and blocking signals from the second end side to the oscillator group side and from the oscillator group side to the first end side; For any combination of two oscillators included in different oscillator groups, the oscillation frequency of each oscillator is set so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range determined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced. A program for executing the above. [Explanation of symbols]

[0142] 1, 2, 3, 4 Quantum Devices 10. Josephson Parametric Oscillator 11 Combiner 12 Circulator 13 Input Ports 14 Output Ports 15 Oscillators 17 Isolator 18, 42 Transmission line 40 Quantum Chip 41 Capacitive coupling 43 Signal Port 44 Coaxial Cable 45 Measuring Instruments

Claims

1. The present invention comprises a plurality of oscillator groups, a plurality of circulators, and a transmission line common to the plurality of circulators, Each of the plurality of oscillator groups includes one or more oscillators having frequency tunability; One or more oscillators included in one oscillator group are connected to one port of a circulator common to the one or more oscillators; each of the plurality of circulators is disposed on the transmission path so as to transmit a signal from a first end of the transmission path to the oscillator group and transmit a signal from the oscillator group to a second end of the transmission path, and to block signals from the second end to the oscillator group and from the oscillator group to the first end. Quantum devices.

2. The oscillation frequencies of all the oscillators included in all the oscillator groups are different from each other. The quantum device of claim 1 .

3. an isolator provided between at least a pair of adjacent circulators in the transmission path, for transmitting a signal from the first end side to the second end side and blocking a signal from the second end side to the first end side; The quantum device of claim 1 or 2, further comprising:

4. One of the circulators and one of the oscillators are connected to each other. The quantum device of claim 1 .

5. At least one of the oscillator groups includes a plurality of the oscillators; For any combination of two oscillators included in the same oscillator group, the oscillation frequency of each oscillator is set so that the magnitude of the difference between the oscillation frequencies of the two oscillators is greater than or equal to the width of a frequency range defined as the frequency range to which the oscillator is susceptible. The quantum device of claim 1 .

6. For any combination of two oscillators included in different oscillator groups, the oscillation frequency of each oscillator is set so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range determined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced. The quantum device of claim 1 .

7. The upper limit of the frequency range to which the oscillator is susceptible is determined to be the oscillation frequency of the oscillator. The quantum device of claim 6.

8. The lower limit of the frequency range to which the oscillator is susceptible is determined to be a frequency calculated based on the oscillation frequency of the oscillator, the Kerr coefficient, and the coherent state amplitude. The quantum device of claim 6.

9. a control device for controlling a quantum device, comprising: a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency tunability, the one or more oscillators included in one oscillator group being connected to one port of a circulator common to the one or more oscillators, each of the plurality of circulators transmitting a signal from a first end side of the transmission path to the oscillator group side, transmitting a signal from the oscillator group side to a second end side of the transmission path, and blocking signals from the second end side to the oscillator group side and from the oscillator group side to the first end side; For any combination of two oscillators included in different oscillator groups, the oscillation frequency of each oscillator is set so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range determined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced. The oscillation frequency setting method includes:

10. a computer that controls a quantum device comprising: a plurality of oscillator groups, a plurality of circulators, and a transmission path common to the plurality of circulators, each of the plurality of oscillator groups comprising one or more oscillators having frequency tunability, one or more oscillators included in one oscillator group being connected to one port of one circulator common to the one or more oscillators, each of the plurality of circulators transmitting a signal from a first end side of the transmission path to the oscillator group side, transmitting a signal from the oscillator group side to a second end side of the transmission path, and blocking signals from the second end side to the oscillator group side and from the oscillator group side to the first end side; For any combination of two oscillators included in different oscillator groups, the oscillation frequency of each oscillator is set so that the oscillation frequency of the oscillator included in the oscillator group on the first end side of the two oscillators is outside a frequency range determined as a frequency range to which the oscillator included in the oscillator group on the second end side is easily influenced. A program for executing the above.

Images