Information processing device, control device, information processing system, and control method

Abstract

To increase the degree of freedom of control for a qubit element whose bit value is to be read out.SOLUTION: An information processing device includes: an information-processing qubit element configured using a Josephson parametric oscillator; a readout qubit element configured using a Josephson parametric oscillator; and a coupler that couples the information-processing qubit element and the readout qubit element, the readout qubit element being coupled to the information-processing qubit element through the coupler so as to take the same bit value as the information-processing qubit element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an information processing device, a control device, an information processing system, and a control method. [Background technology]

[0002] Information processing devices using quantum bit elements, such as quantum annealing machines, have been proposed. For example, Patent Document 1 describes an information processing device that uses a nonlinear oscillator such as a Kerr parametric oscillator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-132188 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to be able to read out bit values ​​from quantum bit elements with as much precision as possible. If there is a large degree of freedom in controlling the quantum bit element from which the bit value is to be read out, the control over that quantum bit element can be made more suitable for reading out the bit value, and it is expected that the bit value can be read out with relatively high precision.

[0005] An example of an object of the present invention is to provide an information processing device, a control device, an information processing system, and a control method that can solve the above-mentioned problems. [Means for solving the problem]

[0006] According to a first aspect of the present invention, an information processing device comprises an information processing quantum bit element, a readout quantum bit element, and a coupler that couples the information processing quantum bit element and the readout quantum bit element, each of which is constructed using a Josephson parametric oscillator, and the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element.

[0007] According to a second aspect of the present invention, a control device comprises an information processing device comprising an information processing quantum bit element, a readout quantum bit element, and a coupler that couples the information processing quantum bit element and the readout quantum bit element, each of which is constructed using a Josephson parametric oscillator, and the control device comprises control means that controls the readout quantum bit element to be coupled to the information processing quantum bit element by the coupler so that the readout quantum bit element has the same bit value as the information processing quantum bit element.

[0008] According to a third aspect of the present invention, an information processing system comprises an information processing device and a control device, wherein the information processing device comprises an information processing quantum bit element, a readout quantum bit element, and a coupler that couples the information processing quantum bit element and the readout quantum bit element, each of which is constructed using a Josephson parametric oscillator, and the control device comprises control means that controls the information processing device so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element.

[0009] According to a fourth aspect of the present invention, a control method includes a control device controlling an information processing device comprising an information processing quantum bit element, a readout quantum bit element, and a coupler coupling the information processing quantum bit element and the readout quantum bit element, each configured using a Josephson parametric oscillator, controlling the information processing device so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element. [Effects of the Invention]

[0010] According to the present invention, it is possible to relatively increase the degree of freedom in controlling the quantum bit element from which the bit value is to be read out. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of an information processing system according to at least one embodiment. [Figure 2] FIG. 2 illustrates a first example of states of an output signal from a quantum bit device according to at least one embodiment. [Figure 3] FIG. 10 illustrates a second example of states of an output signal from a qubit device according to at least one embodiment. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of a control device according to at least one embodiment. [Figure 5] FIG. 2 illustrates a first example of a combination of computational qubit devices and readout qubit devices according to at least one embodiment. [Figure 6] FIG. 10 illustrates a second example of a combination of computational qubit devices and readout qubit devices according to at least one embodiment. [Figure 7] FIG. 10 illustrates a third example of a combination of computational and readout qubit devices according to at least one embodiment. [Figure 8]FIG. 10 illustrates an example of the timing of control for computational and readout qubit devices according to at least one embodiment. [Figure 9] FIG. 3 is a diagram illustrating an example of a procedure of a process performed by a control device according to at least one embodiment. [Figure 10] FIG. 1 is a diagram illustrating a first example of a configuration of an information processing device when using an LHZ model in at least one embodiment. [Figure 11] FIG. 10 is a diagram illustrating a second example of the configuration of an information processing device when using an LHZ model in at least one embodiment. [Figure 12] FIG. 1 is a diagram illustrating an example of a configuration of an information processing device according to at least one embodiment. [Figure 13] FIG. 1 is a diagram showing an example of the configuration of an information processing device according to at least one embodiment, in which an information processing quantum bit element and a readout quantum bit element are referred to as quantum bit elements, and the information processing device is clearly shown to include a plurality of quantum bit elements. [Figure 14] FIG. 2 is a diagram illustrating an example of the configuration of a control device according to at least one embodiment. [Figure 15] FIG. 1 is a diagram illustrating an example of a configuration of an information processing system according to at least one embodiment. [Figure 16] FIG. 1 is a diagram showing an example of the configuration of an information processing system according to at least one embodiment, in which information processing quantum bit elements and readout quantum bit elements are referred to as quantum bit elements, and the information processing device is clearly shown to include multiple quantum bit elements. [Figure 17] FIG. 2 is a diagram illustrating an example of a processing procedure in a control method according to at least one embodiment. [Figure 18] FIG. 1 illustrates an example configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes embodiments of the present invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0013] First Embodiment Fig. 1 is a diagram showing an example of the configuration of an information processing system according to at least one embodiment. In the configuration shown in Fig. 1, the information processing system 1 includes an information processing device 100 and a control device 200. The information processing device 100 includes a plurality of quantum bit devices 110 and a coupler 120. The control device 200 includes a control unit 210 and an observation unit 220.

[0014] The information processing device 100 performs calculations using the quantum bit device 110. The quantum bit element here refers to hardware for expressing a quantum bit value. A Josephson Parametric Oscillator (JPO) can be used as the quantum bit element 110. In the following, an example will be described in which the information processing system 1 performs quantum annealing. However, the calculations performed by the information processing system 1 are not limited to calculations using a specific method. For example, the information processing system 1 may be configured to function as a quantum gate computer.

[0015] The plurality of quantum bit devices 110 included in the information processing device 100 include a computation quantum bit device 111 and a readout quantum bit device 112 . The computational quantum bit device 111 is a quantum bit device 110 that is used to perform computations using quantum annealing.

[0016] The readout quantum bit elements 112 are provided to read out the bit values ​​indicated by the calculation quantum bit elements 111. The readout quantum bit elements 112 are not directly used to perform calculations by quantum annealing. One readout quantum bit element 112 is controlled to indicate the same bit value as the bit value indicated by one calculation quantum bit element 111.

[0017] The bit value indicated by a quantum bit element is also referred to as the bit value of the quantum bit element. When the readout quantum bit element 112 exhibits the same bit value as the calculation quantum bit element 111 , this is also referred to as the readout quantum bit element 112 exhibiting the same bit value as the calculation quantum bit element 111 .

[0018] Here, it is conceivable that the control for quantum annealing will not place the calculation quantum bit element 111 in a state appropriate for reading out the bit value. On the other hand, control separate from the control for quantum annealing can be performed on the readout quantum bit element 112. In this regard, it is expected that control can be performed on the readout quantum bit element 112 so that it is in a state appropriate for reading out the bit value.

[0019] Fig. 2 is a diagram showing a first example of the state of the output signal from the quantum bit device 110. Fig. 2 is a diagram showing the output signal from the quantum bit device 110, separated into an in-phase amplitude component and a quadrature-phase amplitude component, when the quantum bit device 110 is not in an appropriate state for reading out the bit value.

[0020] The photons referred to here are microwave photons that are oscillated within the quantum bit device 110 and output from the quantum bit device 110. The horizontal axis of the graph in Figure 2 represents the in-phase amplitude (I amplitude). The vertical axis represents the quadrature amplitude (Q amplitude). In the graph in Figure 2, the output signal from quantum bit device 110 is measured multiple times, and points are plotted at the coordinate values ​​of the in-phase amplitude (I amplitude) and quadrature amplitude (Q amplitude) for each measurement.

[0021] 2, the reference signal is set to have a phase that is orthogonal to the oscillation output of the quantum bit device 110. The Q amplitude when the reference signal is read as one of the two coherent states (referred to as the first coherent state) is indicated by a positive value. Also, the Q amplitude when the reference signal is read as one of the two coherent states that the quantum bit device 110 can assume, which has a phase difference of π from the first coherent state (referred to as the second coherent state), is indicated by a negative value.

[0022] In the graph of FIG. 2, the distance from the origin (radius vector) corresponds to the oscillation amplitude, and the deflection angle corresponds to the phase of the signal. The graph in Figure 2 shows the results of numerical calculations, plotting the cases where the correct answer is the first coherent state and the second coherent state separately.

[0023] In the example of Figure 2, when the number of photons is small, the signal amplitude becomes small and the Q amplitude decreases. Furthermore, when the noise is large, the uncertainty of the I amplitude and Q amplitude increases. When the noise is large relative to the signal amplitude, the distributions of the first coherent state and the second coherent state overlap, and in the overlapping region, it may be impossible to distinguish which coherent state is in from the I amplitude and Q amplitude obtained from the measurement.

[0024] Fig. 3 is a diagram showing a second example of the state of the output signal from the quantum bit device 110. Fig. 3 is a diagram showing the output signal from the quantum bit device 110, separated into an in-phase amplitude component and a quadrature-phase amplitude component, when the quantum bit device 110 is in a state more appropriate for reading out a bit value. The horizontal axis of the graph in Figure 3 represents the in-phase amplitude (I amplitude). The vertical axis represents the quadrature amplitude (Q amplitude). In the graph in Figure 3, the output signal from quantum bit device 110 is measured multiple times, and points are plotted at the coordinate values ​​of the in-phase amplitude (I amplitude) and quadrature amplitude (Q amplitude) for each measurement.

[0025] In the graph of Figure 3, the reference signal is set to be in quadrature with the oscillation output of the quantum bit device 110. The Q amplitude when the quantum bit device 110 is read as the first coherent state is shown as a positive value, and the Q amplitude when the quantum bit device 110 is read as the second coherent state is shown as a negative value.

[0026] In the graph of FIG. 3, the distance from the origin (radius vector) corresponds to the oscillation amplitude, and the deflection angle corresponds to the phase of the signal. The graph in Figure 3 shows the results of numerical calculations, plotting the cases where the correct answer is the first coherent state and the cases where the correct answer is the second coherent state separately.

[0027] In the example of Figure 3, the average number of photons is larger and the noise is smaller than in the example of Figure 2. This may explain why the example of Figure 3 can read out bit values ​​with higher accuracy than the example of Figure 2. When the number of photons in the output signal of the calculation quantum bit element 111 is small or when there is a lot of noise due to the control for quantum annealing, it is expected that the accuracy of reading out the bit value will be improved by using the readout quantum bit element 112.

[0028] Specifically, the output signal of the calculation quantum bit element 111 is input to the readout quantum bit element 112, and the interaction between these quantum bit elements and the readout quantum bit element 112 are controlled so that the readout quantum bit element 112 shows the same bit value as the calculation quantum bit element 111.

[0029] Here, control of the calculation quantum bit elements 111 and control of the interaction between the calculation quantum bit elements 111 are performed in accordance with the problem that is the target of quantum annealing. On the other hand, control of the readout quantum bit elements 112 and control of the interaction between the calculation quantum bit elements 111 and the readout quantum bit elements 112 are not restricted by the problem that is the target of quantum annealing, and have a higher degree of freedom. As a result, control of the readout quantum bit elements 112 and control of the interaction can be performed so that the output signal of the readout quantum bit element 112 can read out the bit value with higher accuracy than the output signal of the calculation quantum bit element 111. As a result, it is expected that the bit value can be read with higher accuracy by reading it from the readout quantum bit device 112 than by reading it directly from the output of the calculation quantum bit device 111.

[0030] The coupler 120 allows multiple qubit devices 110 to interact with each other. The interaction of multiple qubit devices 110 is also referred to as coupling of the qubit devices. Among couplers, couplers that allow two quantum bit elements to interact with each other are also called two-body couplers. One calculation quantum bit device 111 and one readout quantum bit device 112 are coupled by a two-body coupler 121. Then, the readout quantum bit device 112 and the two-body coupler 121 are controlled so that the readout quantum bit device 112 exhibits the same bit value as the calculation quantum bit device 111.

[0031] The control device 200 controls the information processing device 100 and reads out the results of calculations performed by the information processing device 100. The control device 200 may be configured using a classical computer (von Neumann computer). The control unit 210 controls the information processing device 100. The control unit 210 corresponds to an example of a control means. The observation unit 220 reads out the calculation results obtained by the information processing device 100.

[0032] Fig. 4 is a diagram showing an example of the configuration of the control device 200. In the configuration shown in Fig. 4, the control device 200 includes a control unit 210, an observation unit 220, a communication unit 231, a display unit 232, an operation input unit 233, a storage unit 234, and a processing unit 235. The communication unit 231, the display unit 232, the operation input unit 233, the storage unit 234, and the processing unit 235 may be configured using a computer (classical computer). The control device 200 may be configured as an integrated unit, or may be configured as a combination of multiple devices.

[0033] The communication unit 231 communicates with the control unit 210 and the observation unit 220. For example, the control unit 210 may be connected to the communication unit 231 via a signal line such as a bus. Then, the control unit 210 may generate analog control signals for each of the quantum bit devices 110 and each of the couplers 120 based on a control signal received from the processing unit 235 via the communication unit 231.

[0034] Furthermore, the control unit 210 and the observation unit 220 may be connected to each of the quantum bit devices 110 and each of the couplers 120 via a signal line such as a microwave coaxial cable. The control unit 210 may then transmit an analog control signal to each of the quantum bit devices 110 and each of the couplers 120. The observation unit 220 may also receive an output signal from the quantum bit device 110. For example, the observation unit 220 may digitize the analog signal received from the quantum bit device 110. The digital signal may then be received by the processing unit 235 via the communication unit 231.

[0035] The display unit 232 has a display screen such as a liquid crystal panel or an LED (Light Emitting Diode) panel, and acquires various images. For example, the display unit 232 may display various information related to quantum annealing, such as the results of quantum annealing.

[0036] The operation input unit 233 is configured to include input devices such as a keyboard and a mouse, and accepts user operations. For example, the operation input unit 233 may accept user operations for making various settings related to quantum annealing, such as setting the number of times quantum annealing is to be repeated.

[0037] The storage unit 234 stores various types of data. For example, the storage unit 234 may store various types of data related to quantum annealing, such as a control schedule for the information processing device 100 and the results of each execution of quantum annealing. The storage unit 234 is configured using a storage device provided in the control device 200.

[0038] The processing unit 235 performs various processes by controlling each unit of the control device 200. The functions of the processing unit 235 are performed, for example, by a CPU (Central Processing Unit) included in the control device 200 reading and executing a program from the storage unit 234.

[0039] The control unit 210 controls the information processing device 100 as described above. The observation unit 220 reads out the calculation results obtained by the information processing device 100. The observation unit 220 then digitizes the acquired output signal of the readout quantum bit device 112. The observation unit 220 or the processing unit 235 determines the bit value indicated by the readout quantum bit device 112 based on the digital signal.

[0040] Determination of the bit value based on the digital signal can be performed, for example, by a process of calculating the I amplitude and Q amplitude from a time-series numerical array represented by the digital signal, and a process of determining the bit value based on the I amplitude and Q amplitude. The observation unit 220 may perform these processes, or the processing unit 235 may perform these processes. Alternatively, the observation unit 220 may calculate the I amplitude and Q amplitude, and the processing unit 235 may determine the bit value based on the I amplitude and Q amplitude.

[0041] Fig. 5 is a diagram showing a first example of a combination of a calculation quantum bit element 111 and a readout quantum bit element 112. Fig. 5 shows an example in which a lumped-constant Josephson parametric oscillator is used as the quantum bit element 110. The lumped-constant Josephson parametric oscillator is also referred to as a lumped quantum bit element 110a.

[0042] In the example of FIG. 5, two lumped quantum bit devices 110a are coupled by a two-body coupler 121 implemented using a capacitor 333. In the lumped quantum bit device 110a, a loop is formed between a superconducting quantum interference device (SQUID) 310 having a ring-shaped structure including two Josephson junctions 311 and a capacitor 330. In addition, an inductor (coil) 320 is provided near the SQUID 310 for inputting a pump signal by applying a magnetic field to the ring-shaped structure of the SQUID 310.

[0043] In the loop between the superconducting quantum interference device 310 and the capacitor 330, two ends are provided at positions where the superconducting quantum interference device 310 and the capacitor 330 are connected in parallel. In the configuration of Fig. 5, these two ends are used as a signal input end and a signal output end for both the calculation quantum bit device 111 and the readout quantum bit device 112. The signal input end is also referred to as an input end 351. The signal output end is also referred to as an output end 352.

[0044] In lumped quantum bit device 110a serving as computational quantum bit device 111, input terminal 351 is connected to capacitor 331, and a drive signal is input to input terminal 351 via capacitor 331. Oscillation output is output to the outside from input terminal 351 and output terminal 352 via capacitors 331 and 333 connected thereto, respectively.

[0045] Here, the signal output to the outside via capacitor 331 connected to input terminal 351 may be observed by observation unit 220. In that case, however, it is conceivable that the state of computational quantum bit element 111 will not be appropriate for reading out the bit value due to control for quantum annealing, and therefore the readout result may be one in which the bit state cannot be distinguished, as shown in FIG.

[0046] The oscillation signal output by lumped quantum bit device 110a as calculation quantum bit device 111 is also referred to as an oscillation output signal. The oscillation output signal is input to lumped quantum bit device 110a as readout quantum bit device 112 via capacitor 333 as two-body coupler 121.

[0047] In lumped quantum bit device 110a serving as readout quantum bit device 112, the oscillation output signal from calculation quantum bit device 111 is input to input terminal 351 of readout quantum bit device 112 via capacitor 333 serving as two-body coupler 121. The oscillation signal from lumped quantum bit device 110a serving as readout quantum bit device 112 is output to the outside via capacitors 333 and 332 connected to input terminal 351 and output terminal 352 of readout quantum bit device 112, respectively. Of these, the oscillation signal output from output terminal 352 of readout quantum bit device 112 via capacitor 332 to control device 200 is also referred to as a readout signal. Because control of lumped quantum bit device 110a serving as readout quantum bit device 112 is not subject to the limitations of quantum annealing, it is expected that it can be set to a state appropriate for readout, and the readout result will be one in which the bit states can be distinguished, as shown in FIG. 3.

[0048] A Josephson parametric oscillator is a superconducting nonlinear resonator having a superconducting quantum interference device. In this embodiment, the superconducting quantum interference device has a ring-shaped structure including two Josephson junctions. In a Josephson parametric oscillator, microwaves having a frequency approximately twice the resonant frequency are applied to the superconducting quantum interference device, and the magnetic flux penetrating the ring-shaped structure is modulated at a frequency approximately twice the resonant frequency. As a result, the resonant frequency itself is subjected to parameter modulation, modulated at a frequency approximately twice the original resonant frequency, and the Josephson parametric oscillator parametrically oscillates at half the frequency of the applied microwaves. The microwaves applied at this time are called pump signals. The frequency of the pump signal is called pump frequency. The parametric oscillation performed by a Josephson parametric oscillator takes one of two oscillation states, where the relative phase with respect to the pump signal is either in phase or π out of phase. By treating these two oscillation states as two levels that represent the bit value, the bit value can be expressed by the oscillation state. These two oscillation states correspond to the two coherent states mentioned above.

[0049] Quantum computing using Josephson parametric oscillators uses the technique of adiabatic quantum computation. To adiabatically change the state of a qubit element, it is necessary to set the control parameter values ​​so that the initial state can be reached by adiabatic transition from the final state. To do this, the ground state before excitation must be the ground state when viewed in the coordinate system after excitation.

[0050] Here, in the ground state before excitation, no pump signal is input, and the number of photons in the Josephson parametric oscillator is zero. In addition, a rotating coordinate system is used as the coordinate system after excitation. The Hamiltonian H / h in the rotating coordinate system is expressed as, for example, Equation (1).

[0051]

number

[0052] Δ is the resonant frequency ω of the Josephson parametric oscillator r and the pump frequency ω p This is a value determined according to the frequency difference with half of the frequency, and is expressed as equation (2).

[0053]

number

[0054] A superscripted dagger a indicates a creation operator. a denotes the annihilation operator. χ denotes the nonlinearity. β denotes the strength of the pump signal, which is also called pump strength.

[0055] If the number of photons in a Josephson parametric oscillator is n, then when β=0, the energy is given by nΔ-n(n-1)χ / 2, where n is an integer greater than or equal to 0. Generally, when χ>0 and Δ<0, the ground state when β=0, which has 0 photons, becomes the maximum energy state. In other words, when Δ<0, the energy is maximum when n=0 among n=0, 1, 2, ... If Δ<0 in equation (2), then ω p >2ω r This becomes:

[0056] The energy ground state after parametric oscillation is a coherent state, and in the rotating coordinate system, this coherent state is the state with the maximum energy. Therefore, in order to change the state of a Josephson parametric oscillator adiabatically, it is necessary to make the state with 0 photons when β = 0 the energy maximum state, that is, to make the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. rIn this case, by gradually changing the pump signal strength β from 0 to a finite value, it is possible to change the state of the Josephson parametric oscillator through adiabatic time evolution, and it is expected that a state corresponding to the optimal solution can be obtained.

[0057] On the other hand, if the initial state is not the ground state, a relaxation process involving interactions, including photon exchange, is required to reach the state corresponding to the optimal solution. Therefore, if the initial state is not the ground state, it may take time to reach the state corresponding to the optimal solution. Furthermore, if the initial state is not the ground state, it may also cause a transition to a state that is not the optimal solution.

[0058] Thus, the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r It is preferable to set the value to be greater than twice the value of θ to adiabatically change the state of the Josephson parametric oscillator. In contrast, the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r If the value is set to be greater than twice the value of , the intensity of the oscillation signal output by the Josephson parametric oscillator becomes relatively weak. Here, the Josephson parametric oscillator after excitation enters a coherent state, and the average number of photons in the coherent state, N, is approximated as in equation (3).

[0059]

number

[0060] In equation (3), the larger the value of Δ, the larger the value of the average photon number N, and the stronger the intensity of the oscillation signal. p is the resonant frequency ω of the Josephson parametric oscillator. rIf Δ is greater than twice the normalized value, the strength of the oscillation signal will be weaker than when Δ ≥ 0. It is thought that the inability to make the oscillation signal of the Josephson parametric oscillator strong enough will result in a decrease in the accuracy of reading the bit value.

[0061] In addition to increasing the value of Δ in equation (3), increasing the value of the average photon number N can also be achieved by increasing the value of the pump signal intensity β and decreasing the value of χ, which indicates nonlinearity. However, both β and χ have upper and lower limits determined by the experimental conditions. Therefore, there is a limit to how much the average photon number N can be increased by increasing the value of the pump signal intensity β and decreasing the value of χ, which indicates nonlinearity.

[0062] Furthermore, when reading a bit value from the oscillation signal of a Josephson parametric oscillator, it is possible to amplify the oscillation signal with an amplifier before reading the bit value. However, when the oscillation signal is amplified, the noise contained in the oscillation signal is also amplified. As in the example of Figure 2, when the average number of photons is relatively small, it may be difficult to distinguish between the two coherent states even using the amplified oscillation signal. To read bit values ​​from the oscillation signal of a Josephson parametric oscillator with high accuracy, the oscillation signal before amplification must have a sufficiently large average number of photons, as shown in the example in Figure 3, and the intensity of the oscillation signal must be sufficiently strong relative to the level of noise.

[0063] Therefore, the information processing device 100 is provided with a readout quantum bit device 112. The observation unit 220 does not read out the bit value directly from the calculation quantum bit device 111, but reads out the bit value from the readout quantum bit device 112. As described above, the readout quantum bit element 112 is a quantum bit element 110 that is not directly used to calculate bit values ​​by quantum computing, and has a greater degree of control freedom than the control over the calculation quantum bit element 111. This allows the control unit 210 to control the readout quantum bit element 112 in a manner more suitable for reading out bit values, and it is expected that the bit values ​​can be read out with relatively high accuracy.

[0064] For example, when the quantum bit device 110 is configured using a Josephson parametric oscillator as in the example of FIG. 5, the quantum bit device 111 is configured with a pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r This allows the control unit 210 to change the state of the computation quantum bit device 111 adiabatically.

[0065] On the other hand, for the readout quantum bit device 112, the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r This allows the strength of the readout signal (the oscillation signal output by the readout quantum bit device 112) to be relatively strong, and is expected to enable the observation unit 220 to read out the bit value with relatively high accuracy.

[0066] Furthermore, since there is no need to adiabatically change the state of the readout quantum bit device 112, the value of χ, which indicates nonlinearity, can be made smaller than in the case of the calculation quantum bit device 111. In this respect, too, the strength of the readout signal can be made relatively strong, and it is expected that the observation unit 220 will be able to read out the bit value with relatively high accuracy.

[0067] For two-body coupling, two Josephson parametric oscillators can be two-body coupled by connecting them with a capacitor and inputting pump signals of the same frequency to these two Josephson parametric oscillators. In the example of Figure 5, pump signals of the same frequency are input to the calculation quantum bit element 111 and the readout quantum bit element 112. Note that the "same frequency" here does not have to be exactly the same frequency; it is sufficient that the frequencies match to the extent that the phase does not shift by more than π / 2 during the time required for readout.

[0068] Regarding the resonant frequency, as described above, for the computational qubit device 111, the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r For the readout quantum bit device 112, the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r It is considered that the value should be set to less than twice the value of the Therefore, the resonant frequency of the calculation quantum bit device 111<half the pump frequency common to the calculation quantum bit device 111 and the readout quantum bit device 112<the resonant frequency of the readout quantum bit device 112 may be satisfied.

[0069] Furthermore, the strength of the two-body coupling between the two Josephson parametric oscillators can be changed by the phase difference between the pump signals of these two Josephson parametric oscillators. Therefore, control unit 210 may adjust the relative phase of the pump signal to readout quantum bit device 112 with respect to the phase of the pump signal to calculation quantum bit device 111 so as to maximize the strength of the two-body coupling between calculation quantum bit device 111 and readout quantum bit device 112.

[0070] By coupling the calculation quantum bit element 111 and the readout quantum bit element 112 together, a correlation occurs between the oscillation phases of these two quantum bit elements 110. This is expected to cause the readout quantum bit element 112 to exhibit the same bit value as the bit value exhibited by the calculation quantum bit element 111.

[0071] In particular, since readout quantum bit element 112 is two-body coupled to calculation quantum bit element 111, unlike the case of four-body coupling, readout quantum bit element 112 interacts only with that calculation quantum bit element 111. In this respect, the oscillation phase of readout quantum bit element 112 can directly reflect the oscillation phase of calculation quantum bit element 111.

[0072] Here, if the oscillation phase of calculation quantum bit element 111 is affected by the oscillation phase of readout quantum bit element 112 due to two-body coupling, it is conceivable that the calculation accuracy of bit values ​​by quantum computing will decrease. In particular, it is conceivable that the intensity of the oscillation signal of readout quantum bit element 112 is stronger than the intensity of the oscillation signal of calculation quantum bit element 111, and therefore the oscillation phase of calculation quantum bit element 111 will be easily affected by the oscillation phase of readout quantum bit element 112.

[0073] To avoid or reduce such an effect, control unit 210 may start exciting readout qubit device 112 after the state transition of calculation qubit device 111 is completed and calculation qubit device 111 reaches a coherent state. In other words, control unit 210 may start inputting a pump signal to readout qubit device 112 after the state transition of calculation qubit device 111 is completed, thereby causing the state of readout qubit device 112 to transition.

[0074] 5, the drive signal is input and the oscillation output signal is output at different ends of the computational quantum bit device 111. This eliminates the need to provide a mechanism for separating the output signal from the input signal, such as a circulator, compared to when the drive signal is input and the oscillation output signal is output at the same end of the Josephson parametric oscillator.

[0075] Furthermore, while receiving the input of a drive signal, calculation quantum bit device 111 can output an oscillation output signal and input it to readout quantum bit device 112 via two-body coupler 121. This makes it possible to stabilize the oscillation output signal output by calculation quantum bit device 111, which is expected to lead to improved accuracy in reading out bit values ​​by observation unit 220.

[0076] 5, the input of the oscillation output signal from the calculation quantum bit device 111 and the output of the readout signal are performed at different ends of the readout quantum bit device 112. This eliminates the need to provide a mechanism for separating the output signal from the input signal, such as a circulator, compared to when the input of the drive signal and the output of the oscillation output signal are performed at the same end of the Josephson parametric oscillator.

[0077] Furthermore, the readout quantum bit device 112 can also output a readout signal while receiving an oscillation output signal as input. This makes it possible to stabilize the readout signal output by the readout quantum bit device 112, which is expected to lead to improved accuracy in reading out bit values ​​by the observation unit 220.

[0078] Fig. 6 is a diagram showing a second example of a combination of a calculation quantum bit element 111 and a readout quantum bit element 112. Fig. 6 shows an example in which a distributed constant Josephson parametric oscillator is used as the quantum bit element 110. The distributed constant Josephson parametric oscillator is also referred to as a distributed constant quantum bit element 110b.

[0079] In the example of FIG. 6, two distributed quantum bit devices 110b are coupled by a two-body coupler 121 implemented using a capacitor 333. In the distributed constant type quantum bit device 110b, a superconducting quantum interference device 310 having a ring structure including two Josephson junctions 311 is sandwiched between two λ / 4 resonators (quarter λ resonators) 340. The λ / 4 resonator 340, the superconducting quantum interference device 310, and the λ / 4 resonator 340 are connected in series in this order. In addition, an inductor 320 for inputting a pump signal is provided near one of the two Josephson junctions. Of the two ends of the λ / 4 resonators 340, the end that is not connected to the superconducting quantum interference device 310 corresponds to the end of the distributed constant type quantum bit device 110b.

[0080] In distributed constant quantum bit device 110b serving as computation quantum bit device 111, input terminal 351 is connected to capacitor 331, and a drive signal is input to input terminal 351 via capacitor 331. In addition, an oscillation signal is output from output terminal 352.

[0081] The oscillation signal output by distributed quantum bit device 110b serving as calculation quantum bit device 111 is also referred to as an oscillation output signal. The oscillation output signal is input to distributed quantum bit device 110b serving as readout quantum bit device 112 via capacitor 333 serving as two-body coupler 121.

[0082] In distributed quantum bit device 110b serving as readout quantum bit device 112, an oscillation output signal is input to input terminal 351 via capacitor 333 serving as two-body coupler 121. In addition, output terminal 352 is connected to capacitor 332, and the oscillation signal is output from output terminal 352 via capacitor 332 to control device 200. The oscillation signal output by distributed quantum bit device 110b serving as readout quantum bit device 112 is also referred to as a readout signal.

[0083] When the distributed constant type quantum bit device 110b is used as the quantum bit device 110, as described above, the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r This allows the control unit 210 to change the state of the computation quantum bit device 111 adiabatically.

[0084] Also, for the readout quantum bit device 112, the pump frequency ω p Let ω be the resonant frequency of the Josephson parametric oscillator. r This allows the strength of the readout signal (the oscillation signal output by the readout quantum bit device 112) to be relatively strong, and is expected to enable the observation unit 220 to read out the bit value with relatively high accuracy.

[0085] 6, since there is no need to adiabatically change the state of the readout quantum bit device 112, the value of χ, which indicates nonlinearity, can be made smaller than in the case of the calculation quantum bit device 111. In this respect, too, the strength of the readout signal can be made relatively strong, and it is expected that the observation unit 220 will be able to read out the bit value with relatively high accuracy.

[0086] 6, by inputting pump signals of the same frequency to the calculation quantum bit device 111 and the readout quantum bit device 112, it is possible to couple the two quantum bit devices 111 and 112. Note that the same frequency here does not have to be exactly the same frequency, as long as the frequencies match to the extent that the phase does not shift by more than π / 2 during the time required for readout.

[0087] In the example of Figure 6, the control unit 210 may also adjust the relative phase of the pump signal to the readout quantum bit element 112 with respect to the phase of the pump signal to the calculation quantum bit element 111 so as to maximize the strength of the two-body coupling between the calculation quantum bit element 111 and the readout quantum bit element 112.

[0088] 6, the calculation quantum bit element 111 and the readout quantum bit element 112 are coupled together, which generates a correlation between the oscillation phases of these two quantum bit elements 110. This is expected to cause the readout quantum bit element 112 to indicate the same bit value as the calculation quantum bit element 111.

[0089] In particular, since readout quantum bit element 112 is two-body coupled to calculation quantum bit element 111, unlike the case of four-body coupling, readout quantum bit element 112 interacts only with that calculation quantum bit element 111. In this respect, the oscillation phase of readout quantum bit element 112 can directly reflect the oscillation phase of calculation quantum bit element 111.

[0090] 6, control unit 210 may also be configured to start exciting readout quantum bit device 112 after the state transition of calculation quantum bit device 111 is completed and calculation quantum bit device 111 reaches a coherent state. In other words, control unit 210 may start inputting a pump signal to readout quantum bit device 112 after the state transition of calculation quantum bit device 111 is completed, thereby causing the state of readout quantum bit device 112 to transition.

[0091] 6, the drive signal is input and the oscillation output signal is output at different ends of the computational quantum bit device 111. This eliminates the need to provide a mechanism for separating the output signal from the input signal, such as a circulator, compared to when the drive signal is input and the oscillation output signal is output at the same end of the Josephson parametric oscillator.

[0092] 6, while receiving an input of a drive signal, calculation quantum bit device 111 can output an oscillation output signal and input it to readout quantum bit device 112 via two-body coupler 121. This makes it possible to stabilize the oscillation output signal output by calculation quantum bit device 111, which is expected to lead to improved accuracy in reading out bit values ​​by observation unit 220.

[0093] 6, the input of the oscillation output signal from the calculation quantum bit device 111 and the output of the readout signal are performed at different ends in the readout quantum bit device 112. This eliminates the need to provide a mechanism for separating the output signal from the input signal, such as a circulator, compared to when the input of the drive signal and the output of the oscillation output signal are performed at the same end of the Josephson parametric oscillator.

[0094] 6, readout quantum bit device 112 can also output a readout signal while receiving an oscillation output signal as input. This makes it possible to stabilize the readout signal output by readout quantum bit device 112, which is expected to lead to improved accuracy in reading out bit values ​​by observation unit 220.

[0095] 7 is a diagram showing a third example of a combination of a calculation quantum bit element 111 and a readout quantum bit element 112. FIG. 7 shows another example in which a lumped constant Josephson parametric oscillator is used as the quantum bit element 110. In the example of FIG. 7, the way in which the loop between the superconducting quantum interference device 310 and the capacitor 330 is set is different from that in FIG.

[0096] 7, in both the calculation quantum bit device 111 and the readout quantum bit device 112, one of the two ends located at a position where the superconducting quantum interference device 310 and the capacitor 330 are connected in parallel is connected to a signal path, and the other end is grounded (GND). Otherwise, the example of FIG. 7 is similar to that of FIG. In this way, only one of the two ends of the loop between the superconducting quantum interference device 310 and the capacitor 330 may be connected to the signal path. This end is also referred to as an input / output end 353.

[0097] Note that a mixture of lumped Josephson parametric oscillators and distributed Josephson parametric oscillators may be used. For example, lumped quantum bit element 110a may be used as calculation quantum bit element 111, and distributed quantum bit element 110b may be used as readout quantum bit element 112. Alternatively, distributed quantum bit element 110b may be used as calculation quantum bit element 111, and lumped quantum bit element 110a may be used as readout quantum bit element 112.

[0098] FIG. 8 is a diagram showing an example of the timing of control over the calculation quantum bit device 111 and the readout quantum bit device 112. In FIG. 8, graphs G1 to G4 are shown aligned in time. Graph G1 is a graph showing the input timing of a drive signal to the calculation quantum bit device 111. Graph G2 is a graph showing the input timing of a pump signal to the calculation quantum bit device 111. Graph G3 is a graph showing the input timing of a pump signal to the readout quantum bit device 112. Graph G4 is a graph showing the timing of reading out a readout signal from the readout quantum bit device 112.

[0099] The horizontal axis of each graph indicates the time elapsed from a predetermined reference time. The vertical axes of graphs G1 to G3 represent the strength of the input signal to the quantum bit device 110, normalized to a value in the range from 0 to 1. The value 0 on the vertical axis represents the signal strength when no signal is input to the quantum bit device 110. The value 1 on the vertical axis represents the signal strength that is set as a steady value.

[0100] The vertical axis of graph G4 indicates whether the readout interval is on (ON) or off (OFF). The readout interval here is the time interval during which the oscillation signal is read out from the quantum bit device 110. When the readout interval is on, it indicates that the observation unit 220 is reading out the oscillation signal. When the readout interval is off, it indicates that the observation unit 220 is not reading out the oscillation signal.

[0101] 8, the control unit 210 starts inputting a drive signal and a pump signal to the computation quantum bit device 111 at time T1, and sets the intensities of these signals to steady values ​​at time T2. Before time T1, when no pump signal is being input, the computation quantum bit device 111 is in its initial state. After time T2, when the intensity of the pump signal has reached its steady value, the computation quantum bit device 111 is in a coherent state (i.e., a state in which the quantum bit value is fixed to one of two values).

[0102] Furthermore, the control unit 210 starts inputting a pump signal to the readout quantum bit device 112 at time T3, which is later than time T2, and sets the intensity of the pump signal to a steady value at time T4. Before time T3, when no pump signal is being input, the state of the readout quantum bit device 112 is in its initial state. After time T4, when the intensity of the pump signal has reached its steady value, the state of the readout quantum bit device 112 becomes a coherent state.

[0103] The observation unit 220 reads out the readout signal (oscillation signal from the readout quantum bit device 112) during the readout period from time T5 to T6, which is after time T4 when the intensity of the pump signal from the readout quantum bit device 112 reaches a steady value. From time T7 to T8 after time T6, control unit 210 reduces the intensity of the pump signal to readout quantum bit device 112, and ends the input of the pump signal to readout quantum bit device 112 at time T8.

[0104] 8, the control unit 210 can input a pump signal to the readout quantum bit device 112 to start excitation after the time when the calculation quantum bit device 111 reaches a coherent state. This makes it possible to avoid or reduce the influence of the oscillation phase of the readout quantum bit device 112 on the oscillation phase of the calculation quantum bit device 111, as described above.

[0105] Furthermore, when a pump signal is input to the Josephson parametric oscillator so that Δ>0, and a drive signal is input, the Josephson parametric oscillator can be excited in synchronization with the drive signal. Therefore, after the state of the calculation quantum bit device 111 becomes a coherent state, the control unit 210 may input a pump signal to the readout quantum bit device 112 so that Δ>0. This is expected to cause the readout quantum bit device 112 to oscillate in the same phase as the oscillation phase of the calculation quantum bit device 111, and enable the observation unit 220 to read out the bit value indicated by the calculation quantum bit device 111 from the readout quantum bit device 112.

[0106] Also, Δ>0 means that the pump frequency ω p is the resonant frequency ω of the Josephson parametric oscillator. r This corresponds to being smaller than twice the normalized value. Therefore, as described above, the intensity of the oscillation signal from the readout quantum bit device 112 becomes relatively strong. This is expected to enable the observation unit 220 to read out the bit value indicated by the readout quantum bit with relatively high accuracy.

[0107] Fig. 9 is a diagram showing an example of the procedure of processing performed by the control device 200. Fig. 9 shows an example of the procedure of processing performed by the control device 200 in one solution search in quantum annealing. The control device 200 repeats the processing of Fig. 9 the same number of times as the solution search in quantum annealing is repeated.

[0108] 9, the control unit 210 controls the calculation quantum bit device 111 (step S11). Specifically, the control unit 210 inputs a control signal such as a pump signal to the calculation quantum bit device 111 via the communication unit 231.

[0109] After the calculation quantum bit device 111 has entered a coherent state, the control unit 210 controls the readout quantum bit device 112 (step S12). Specifically, the control unit 210 inputs a control signal such as a pump signal to the readout quantum bit device 112.

[0110] After the readout quantum bit device 112 enters a coherent state, the observation unit 220 reads out the bit value from the readout quantum bit device 112 (step S13). Specifically, the observation unit 220 measures the phase of the readout signal, which is an oscillation signal output by the readout quantum bit device 112, to estimate the bit value. After step S13, the control device 200 ends the processing of Fig. 9. End here refers to the end of the output from the control unit 210 and the measurement of the readout signal in the observation unit 220.

[0111] Note that, although the information processing quantum bit has been described as an example where it is a calculation quantum bit, the information processing quantum bit may also be used for purposes other than calculation. As described above with respect to the calculation quantum bit element, the calculation quantum bit is a quantum bit used to perform calculations. The information processing quantum bit is a quantum bit that is not limited to calculations and is used widely for information processing. For example, the information processing quantum bit may be used as a memory bit.

[0112] As described above, the readout quantum bit device 112 is coupled to the information processing quantum bit device by the coupler 120 so as to have the same bit value as the information processing quantum bit device. In information processing device 100, the control over read quantum bit device 112 does not need to be the same as the control over the information processing quantum bit device, and there is a relatively large degree of freedom in the control over read quantum bit device 112. This makes it possible to control read quantum bit device 112 in a way that is more suitable for reading out bit values, and is expected to enable information processing device 100 to read out bit values ​​with higher accuracy.

[0113] The information processing quantum bit device is the computation quantum bit device 111. In the information processing device 100, under the control of the control device 200, calculations such as quantum annealing can be performed.

[0114] Furthermore, the mutually coupled readout quantum bit device 112 and calculation quantum bit device 111 are excited at the same frequency. Note that the "same frequency" referred to here does not have to be exactly the same frequency, but only needs to match to the extent that the phase does not shift by more than π / 2 during the time required for readout. As a result, in the information processing device 100, these two quantum bit devices 110 can be coupled together so that the read quantum bit device 112 has the same bit value as the calculation quantum bit device 111. As a result, it is expected that the information processing device 100 can read out from the read quantum bit device 112 the same bit value as the bit value of the calculation quantum bit device 111.

[0115] The pump frequency of the calculation quantum bit device 111 is greater than twice the resonant frequency, and the pump frequency of the readout quantum bit device 112 is less than twice the resonant frequency. In the information processing device 100, the pump frequency of the calculation quantum bit element 111 is greater than twice the resonant frequency, so that the state of the calculation quantum bit element 111 can be changed adiabatically. Furthermore, the pump frequency of the readout quantum bit element 112 is less than twice the resonant frequency, so that the intensity of the oscillation signal of the readout quantum bit element 112 can be made relatively strong. In this respect, the information processing device 100 is expected to be able to read out bit values ​​with relatively high accuracy.

[0116] Furthermore, the mutually coupled readout quantum bit device 112 and calculation quantum bit device 111 are excited at the same pump frequency. The resonant frequency of calculation quantum bit device 111 is smaller than half the pump frequency. The resonant frequency of readout quantum bit device 112 is larger than half the pump frequency.

[0117] In the information processing device 100, the readout quantum bit device 112 and the calculation quantum bit device 111 are excited at the same pump frequency, so that these two quantum bit devices 110 can be coupled together to take on the same value. As a result, it is expected that the information processing device 100 will be able to read out from the readout quantum bit device 112 the same bit value as the bit value of the calculation quantum bit device 111.

[0118] Furthermore, in the information processing device 100, the resonant frequency of the calculation quantum bit element 111 is smaller than half the pump frequency, so that the state of the calculation quantum bit element 111 can be changed adiabatically. Furthermore, the resonant frequency of the readout quantum bit element 112 is larger than half the pump frequency, so that the phase of the oscillation signal of the readout quantum bit element 112 can be synchronized with the phase of the oscillation signal of the calculation quantum bit element 111, and the intensity of the oscillation signal of the readout quantum bit element 112 can be made relatively strong. In this respect, it is expected that the information processing device 100 will be able to read out bit values ​​with relatively high accuracy.

[0119] Furthermore, the control unit 210 can excite the readout quantum bit device 112 after the calculation quantum bit device 111 reaches a coherent state. In this regard, it is expected that the information processing device 100 will make it easy to control the readout quantum bit element 112 so that the bit value of the readout quantum bit element 112 becomes the same as the bit value of the calculation quantum bit element 111. In this regard, it is expected that the information processing device 100 will be able to read out from the readout quantum bit element the same bit value as the bit value of the calculation quantum bit element 111.

[0120] Second Embodiment In the second embodiment, a first example will be described in which the information processing system 1 is applied to an LHZ system model. The LHZ system model is also referred to as an LHZ model. In the second embodiment, the configuration of the information processing device 100 is specific to the configuration in the first embodiment. In other respects, the configuration of the information processing system 1 in the second embodiment is the same as that in the first embodiment.

[0121] Fig. 10 is a diagram showing a first example of the configuration of information processing device 100 when using the LHZ model. In the example of Fig. 10, information processing device 100 includes eight calculation quantum bit devices 111, three readout quantum bit devices 112, three two-body couplers 121, and three four-body couplers 122. Just as two-body coupler 121 is an example of coupler 120, four-body coupler 122 is also an example of coupler 120. The configuration of the information processing device 100 shown in FIG. 10 corresponds to a specific example of the configuration of the information processing device 100 shown in FIG.

[0122] When distinguishing between the eight calculation quantum bit devices 111, they are also referred to as calculation quantum bit devices 111-1, 111-2, ..., 111-8. When distinguishing between the three readout quantum bit devices 112, they are also referred to as readout quantum bit devices 112-1, 112-2, 112-3. When distinguishing between the three two-body couplers 121, they are also referred to as two-body couplers 121-1, 121-2, 121-3. When distinguishing between the three four-body couplers 122, they are also referred to as four-body couplers 122-1, 122-2, 122-3.

[0123] 10 shows an example in which a readout quantum bit element 112 is provided in a physical model obtained by converting a 4-bit fully connected logical model using the LHZ method. However, the information processing device 100 is applicable to problems represented by logical models with various numbers of bits, not limited to 4 bits.

[0124] The bit value of each of calculation qubit elements 111-1 to 111-6 indicates the product of two logical bits. In the representation of these calculation qubit elements 111, two numbers shown in circles indicate the identification numbers of the logical bits to be multiplied. For example, the bit value of calculation qubit element 111-1 indicates the product of the first logical bit and the fourth logical bit. Computational quantum bit devices 111-7 and 111-8 are controlled so that the bit value becomes a fixed value of +1. Each of the four-body couplers 122 couples four computational quantum bit devices 111. In the representation of the four-body couplers 122, the "4" shown in the square indicates that the coupling number (the number of quantum bit devices that the coupler couples) is four.

[0125] Of the calculation quantum bit devices 111-1 to 111-6, calculation quantum bit devices 111-4 to 111-6 are the targets for reading out bit values. However, the observation unit 220 does not read out bit values ​​directly from the calculation quantum bit devices 111, but reads out bit values ​​from the readout quantum bit devices 112. The configuration in FIG. 10 can be understood as a configuration in which a readout quantum bit device 112 is provided via a two-body coupler 121 in an LHZ system model formed by a calculation quantum bit device 111 and a four-body coupler 122.

[0126] Furthermore, each of the multiple quantum bit elements 110 is configured using a nonlinear oscillator. Of the readout quantum bit element 112 and the calculation quantum bit element 11, which are coupled to each other, it is conceivable to make the nonlinearity of the readout quantum bit element 112 smaller than the nonlinearity of the calculation quantum bit element 111.

[0127] According to the information processing device 100, the nonlinearity of the readout quantum bit element 112 is smaller than the nonlinearity of the calculation quantum bit element 111, and it is expected that the intensity of the output signal of the readout quantum bit element 112 can be made greater than the intensity of the output signal of the calculation quantum bit element 111. In this respect, it is expected that the information processing device 100 can read out bit values ​​with higher accuracy than when bit values ​​are read out directly from the calculation quantum bit element 111.

[0128] Each readout quantum bit device 112 is coupled to one computation quantum bit device 111 by a two-body coupler 121. The readout quantum bit devices 112 are controlled to exhibit the same bit value as the computation quantum bit device 111 to which they are coupled. Specifically, readout quantum bit device 112-1 is coupled to computation quantum bit device 111-4 by a two-body coupler 121-1, and is controlled to exhibit the same bit value as computation quantum bit device 111-4. Readout quantum bit device 112-2 is coupled to computation quantum bit device 111-5 by a two-body coupler 121-2, and is controlled to exhibit the same bit value as computation quantum bit device 111-5. Readout quantum bit device 112-3 is coupled to computation quantum bit device 111-6 by a two-body coupler 121-3, and is controlled to exhibit the same bit value as computation quantum bit device 111-6.

[0129] In the representation of the two-body coupler 122, the number "2" shown in the square indicates that the number of couplings is two. Observation unit 220 reads out the bit values ​​of readout quantum bit devices 112-1 to 112-3, thereby reading out the bit values ​​of calculation quantum bit devices 111-4 to 111-6.

[0130] When quantum annealing is performed using the LHZ method with a Josephson parametric oscillator, pump signals are simultaneously input to the Josephson parametric oscillator to cause interactions, and the state is changed adiabatically until a coherent state is reached.

[0131] 10 , the control unit 210 simultaneously inputs pump signals to the calculation quantum bit device 111 to cause them to interact with each other, while adiabatically changing the state until a coherent state is reached. After the calculation quantum bit device 111 reaches a coherent state, the control unit 210 inputs a pump signal to the readout quantum bit device 112 to cause a two-body interaction with the calculation quantum bit device 111. The observation unit 220 then reads out the bit value from the readout quantum bit device 112.

[0132] In the second embodiment, the information processing quantum bit is also described as a calculation quantum bit, but the information processing quantum bit may be used for purposes other than calculation.

[0133] As described above, calculation quantum bit device 111 and one or more four-body couplers 122 of coupler 120 form an LHZ model. It is expected that the information processing device 100 will be able to read out bit values ​​from an LHZ model with higher accuracy, and in this respect, it is expected that the information processing device 100 will be able to calculate solutions to problems represented by fully connected logical models with higher accuracy. In particular, in the information processing device 100, the control over the readout quantum bit element 112 does not need to be the same as the control over the calculation quantum bit element 111, and there is a relatively large degree of freedom in the control over the readout quantum bit element 112. This is expected to enable the information processing device 100 to control the readout quantum bit element 112 in a way that is more suitable for reading out bit values, thereby enabling the bit values ​​to be read out with higher accuracy.

[0134] <Third embodiment> In the third embodiment, a second example in which the information processing system 1 is applied to an LHZ system model will be described. In the third embodiment, the configuration of the information processing device 100 is specific to the configuration in the case of the first embodiment. In other respects, the configuration of the information processing system 1 in the third embodiment is similar to that in the case of the first embodiment.

[0135] Fig. 11 is a diagram showing a second example of the configuration of an information processing device 100 when using the LHZ model. In the example of Fig. 11, the information processing device 100 includes 22 quantum bit elements 110 and 13 four-body couplers 122. Eight of the 22 quantum bit elements 110 are used as calculation quantum bit elements 111. The arrangement and use of the quantum bit elements 110 used as calculation quantum bit elements 111 are the same as in Fig. 10, and as in Fig. 10, they are also referred to as calculation quantum bit elements 111-1, 111-2, ..., 111-8.

[0136] Of the remaining 14 quantum bit devices 110, three are used as readout quantum bit devices 112. The arrangement and use of the quantum bit devices 110 used as readout quantum bit devices 112 are the same as in Fig. 10, and as in Fig. 10, they are also referred to as readout quantum bit devices 112-1, 112-2, and 112-3. The remaining 11 quantum bit devices 110 are unused.

[0137] To distinguish between the four-body couplers 122 in the example of FIG. 11, they are also referred to as four-body couplers 122-1, 122-2, . . . , 122-13. Four-body couplers 122-1 to 122-3 couple four computational quantum bit devices 111 together, as in the case of FIG. 10. Meanwhile, four-body couplers 122-4 to 122-6 each couple one calculation quantum bit device 111 and one readout quantum bit device 112, similar to two-body couplers 121-1 to 121-3 in FIG. The four-body couplers 122-7 to 122-13 are not used.

[0138] The control unit 210 may be configured not to parametrically excite unused quantum bit devices 110. In the four-body coupling of Josephson parametric oscillators, the pump frequencies of the four Josephson parametric oscillators are set to satisfy the relationship of equation (4).

[0139]

number

[0140] ω p,1 , ω p,2 , ω p,3 , ω p,4 denotes the pump frequencies of four four-body coupled Josephson parametric oscillators. In the case of four-body coupling, the pump frequency ω of the four coupled Josephson parametric oscillators is p,1 , ω p,2 , ω p,3 , ω p,4 By making all of these values ​​different, two-body bonds are prevented from occurring.

[0141] In the example of Figure 11, for example, the control unit 210 sets the frequencies of the pump signals input to the four calculation quantum bit devices 111 to different values ​​so that the four-body coupler 122-1 couples the four calculation quantum bit devices 111-1, 111-2, 111-3, and 111-5 in a four-body manner, and also so that the relationship in equation (4) holds.

[0142] On the other hand, when two Josephson parametric oscillators are coupled in two-body fashion using a four-body coupler, the pump frequencies of the two Josephson parametric oscillators are made the same. In the example of Figure 11, for example, the control unit 210 sets the frequency of the pump signal input to the calculation quantum bit element 111 to the frequency of the pump signal input to the readout quantum bit element to the same value so that the four-body coupler 122-4 couples the calculation quantum bit element 111 and the readout quantum bit element two-body.

[0143] The resonant frequency of the two uncoupled quantum bit devices 110 can be considered to be sufficiently decoupled from the resonant frequency of the two coupled quantum bit devices 110. For example, the resonant frequency can be adjusted by inputting a direct current to the inductor 320 and changing the magnetic flux passing through the annular structure of the superconducting quantum interference device 310.

[0144] The configuration in Figure 11 corresponds to a circuit structure that extends the LHZ method. A maximum of a 6-bit fully connected logical model can be embedded in this circuit using the LHZ method. This circuit can be considered as an example of applying it to a problem represented by a 4-bit fully connected logical model, and using several quantum bit elements 110 as readout quantum bit elements 112. In this way, a circuit that can handle an LHZ model that is larger than the problem to be solved may be used, and some of the quantum bit elements 110 that are not used in the solution search using quantum annealing may be used as readout quantum bit elements 112.

[0145] 11 , control unit 210 also simultaneously inputs pump signals to calculation quantum bit device 111 to cause them to interact with each other, while adiabatically changing the state until a coherent state is reached. After calculation quantum bit device 111 reaches a coherent state, control unit 210 inputs a pump signal to readout quantum bit device 112 to cause a two-body interaction with calculation quantum bit device 111. Then, observation unit 220 reads out the bit value from readout quantum bit device 112.

[0146] The circuit structure of the information processing device 100 in the third embodiment is not limited to a specific shape (network structure) as long as it can embed an LHZ model. For example, the information processing device 100 may be configured in the shape of an LHZ model, or may be configured in a square shape.

[0147] In the third embodiment, the information processing quantum bit is also described as a calculation quantum bit, but the information processing quantum bit may be used for purposes other than calculation.

[0148] As described above, information processing device 100 is configured with a circuit including a plurality of quantum bit elements 110 and four-body couplers 122, which are couplers 120, in which an LHZ model, a model based on the LHZ method, is implemented in a circuit with a logical model having a larger number of bits than the problem being the target of quantum computing. Control unit 210 controls information processing device 100 to operate one or more quantum bit elements 110 as calculation quantum bit elements 111, to operate one or more quantum bit elements 110 other than calculation quantum bit elements 111 as readout quantum bit elements 112, and to couple one readout quantum bit element 112 and one calculation quantum bit element 111 in two-body fashion in each of four-body couplers 122 that couples readout quantum bit elements 112 to other quantum bit elements 110.

[0149] According to the information processing device 100, it is possible to provide the readout quantum bit element 112 to the information processing device 100, which is capable of implementing a physical model obtained by converting a logical model using the LHZ method, without the need to separately add a quantum bit element 110 used as the readout quantum bit element 112. This is expected to enable the information processing device 100 to read out bit values ​​from an LHZ method model with higher accuracy. In this respect, it is expected that the information processing device 100 will be able to calculate solutions to problems represented by fully connected logical models with higher accuracy.

[0150] <Fourth embodiment> 12 is a diagram illustrating an example of the configuration of an information processing device according to at least one embodiment. In the configuration illustrated in FIG. 12, information processing device 610 includes information processing quantum bit device 611, readout quantum bit device 612, and coupler 613.

[0151] In this configuration, coupler 613 couples information processing quantum bit device 611 and readout quantum bit device 612. Readout quantum bit device 612 is coupled to information processing quantum bit device 611 by coupler 613 so that readout quantum bit device 612 has the same bit value as information processing quantum bit device 611.

[0152] In the information processing device 610, the control over the readout quantum bit device 612 does not need to be the same as the control over the information processing quantum bit device 611. In this respect, the information processing device 610 has a relatively large degree of freedom in controlling the readout quantum bit device 612. This is expected to enable the information processing device 610 to control the readout quantum bit device 612 in a way that is more suitable for reading out bit values, thereby enabling the bit values ​​to be read out with higher accuracy.

[0153] FIG. 13 is a diagram showing an example of the configuration of an information processing device 610, in which the information processing quantum bit element 611 and the readout quantum bit element 612 are represented as quantum bit elements 614, and the information processing device 610 is clearly shown to have multiple quantum bit elements 614. The information processing device 610 includes one or more information processing qubit devices and one or more readout qubit devices as qubit devices 614. The information processing qubit devices may also be used as computational qubit devices.

[0154] Fifth Embodiment 14 is a diagram illustrating an example of the configuration of a control device according to at least one embodiment. In the configuration illustrated in FIG. In this configuration, the control unit 621 controls an information processing device that includes an information processing quantum bit element, a readout quantum bit element, and a coupler that couples the information processing quantum bit element and the readout quantum bit element together, so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so that the readout quantum bit element has the same bit value as the information processing quantum bit element. The control unit 621 corresponds to an example of a control means.

[0155] With control device 620, the control of the readout quantum bit element does not need to be the same as the control of the information processing quantum bit element, and there is a relatively large degree of freedom in the control of the readout quantum bit element. This is expected to enable control device 620 to control the readout quantum bit element in a way that is more suitable for reading out bit values, thereby enabling more accurate reading of bit values.

[0156] Sixth Embodiment 15 is a diagram showing an example of the configuration of an information processing system according to at least one embodiment. In the configuration shown in Fig. 15, information processing system 630 includes information processing device 631 and control device 635. Information processing device 631 includes information processing quantum bit device 632, readout quantum bit device 633, and coupler 634. Control device 635 includes control unit 636.

[0157] In this configuration, the coupler 634 couples the information processing quantum bit device 632 with the readout quantum bit device 633. The control unit 636 controls the information processing device 631 so that the readout quantum bit device 633 is coupled to the information processing quantum bit device 632 by the coupler 634 so that the readout quantum bit device 633 has the same bit value as the information processing quantum bit device 632. The control unit 636 is an example of a control means.

[0158] In information processing system 630, control unit 636 does not need to control readout quantum bit element 633 in the same way as it controls information processing quantum bit element 632. In this respect, information processing system 630 has a relatively large degree of freedom in controlling readout quantum bit element 633. This is expected to enable information processing system 630 to control readout quantum bit element 633 in a way that is more suitable for reading out bit values, thereby enabling bit values ​​to be read out with higher accuracy.

[0159] Figure 16 is a diagram showing an example of the configuration of an information processing system 630, in which the information processing quantum bit element 632 and the readout quantum bit element 633 are represented as quantum bit elements 637, and the information processing device 631 is clearly shown to have multiple quantum bit elements 637. The information processing device 631 includes one or more information processing quantum bit devices and one or more readout quantum bit devices as the quantum bit devices 637. The information processing quantum bit devices may be used as calculation quantum bit devices.

[0160] Seventh Embodiment 17 is a diagram showing an example of a processing procedure in a control method according to at least one embodiment. The control method shown in FIG. 17 includes controlling an information processing device (step S611). In controlling the information processing device (step S611), a control device that controls an information processing device that has an information processing quantum bit element, a readout quantum bit element, and a coupler that couples the information processing quantum bit element and the readout quantum bit element controls the information processing device so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so that the readout quantum bit element has the same bit value as the information processing quantum bit element.

[0161] According to the control method shown in Fig. 17, the control of the readout quantum bit element does not need to be the same as the control of the information processing quantum bit element, and the degree of freedom in controlling the readout quantum bit element is relatively large. As a result, with the control method shown in Fig. 17, the control of the readout quantum bit element can be made more suitable for reading out the bit value, and it is expected that the bit value can be read out with higher accuracy.

[0162] FIG. 18 illustrates an example configuration of a computer according to at least one embodiment. In the configuration shown in FIG. 18, a computer 700 includes a CPU 710, a main memory device 720, an auxiliary memory device 730, an interface 740, and a non-volatile recording medium 750. Furthermore, computer 700 is communicatively connected to quantum device 760. For example, as in the example of Fig. 4, computer 700 may be communicatively connected to quantum device 760 via a control unit that converts a control signal from computer 700 into an analog control signal and transmits it to quantum device 760, and an observation unit that converts the analog signal from quantum device 760 into a digital signal. Quantum device 760 may be configured as part of computer 700. Alternatively, quantum device 760 may be configured external to computer 700.

[0163] One or more of the control devices 200, 620, and 635, or a part thereof, may be implemented in the computer 700. In this case, the operation of each of the above-described processing units is stored in the auxiliary storage device 730 in the form of a program. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above-described processing in accordance with the program. The CPU 710 also allocates storage areas in the main storage device 720 corresponding to each of the above-described storage units in accordance with the program. Communication between each device and other devices is performed by an interface 740 having a communication function and performing communication under the control of the CPU 710. The interface 740 also has a port for a nonvolatile recording medium 750, and reads information from the nonvolatile recording medium 750 and writes information to the nonvolatile recording medium 750.

[0164] The quantum device 760 is a device (circuit) that operates using a quantum state in quantum mechanics. The quantum device 760 operates as described above in each embodiment for quantum computing such as quantum annealing.

[0165] When the control device 200 is implemented in a computer 700, the operations of the processing unit 235 and each of its units are 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 into the main storage device 720, and executes the above-described processing in accordance with the program.

[0166] Furthermore, the CPU 710 allocates a storage area for the storage unit 234 in the main storage device 720 in accordance with the program. Communication with other devices by the communication unit 231 is performed by the interface 740 having a communication function and operating under the control of the CPU 710. Display of images by the display unit 232 is performed by the interface 740 having a display device and displaying various images under the control of the CPU 710. Reception of user operations by the operation input unit 233 is performed by the interface 740 having an input device and receiving the user operations under the control of the CPU 710.

[0167] When the control device 620 is implemented in the computer 700, the operation of the control unit 621 is stored in the form of a program in the auxiliary storage device 730. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above-mentioned processing in accordance with the program.

[0168] Furthermore, the CPU 710 allocates a storage area in the main memory device 720 for the control device 620 to perform processing in accordance with the program. Communication between the control device 620 and other devices is performed by the interface 740, which has a communication function and operates under the control of the CPU 710. Interaction between the control device 620 and a user is performed by the interface 740, which has an input device and an output device, presenting information to the user via the output device under the control of the CPU 710 and accepting user operations via the input device.

[0169] When the control device 635 is implemented in the computer 700, the operation of the control unit 636 is stored in the form of a program in the auxiliary storage device 730. The CPU 710 reads the program from the auxiliary storage device 730, loads it into the main storage device 720, and executes the above-mentioned processing in accordance with the program.

[0170] Furthermore, the CPU 710 allocates a storage area in the main storage device 720 for the control device 635 to perform processing in accordance with the program. Communication between the control device 635 and other devices is performed by the interface 740, which has a communication function and operates under the control of the CPU 710. Interaction between the control device 635 and a user is performed by the interface 740, which has an input device and an output device, presenting information to the user via the output device under the control of the CPU 710 and accepting user operations via the input device.

[0171] One or more of the above-described programs may be recorded on nonvolatile recording medium 750. In this case, interface 740 may read the programs from nonvolatile recording medium 750. CPU 710 may then directly execute the programs read by interface 740, or may temporarily store the programs in main storage device 720 or auxiliary storage device 730 and then execute them.

[0172] Note that a program for executing all or part of the processing performed by control device 200, control device 620, and control device 635 may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to perform the processing of each unit. Note that the term "computer system" here includes hardware such as an OS (Operating System) and peripheral devices. Furthermore, "computer-readable recording media" 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 program may be one that realizes part of the aforementioned functions, or may be one that can realize the aforementioned functions in combination with a program already stored in the computer system.

[0173] Although the embodiments have been described above, the specific configuration is not limited to these embodiments, and designs within the scope of the present invention are also included. Furthermore, the above-described embodiments can be appropriately combined with other embodiments. In the above-described embodiments, the number of Josephson junctions in the superconducting quantum interference device has been described as two, but the number of Josephson junctions may be three or more.

[0174] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0175] (Appendix 1) a quantum bit element for information processing and a quantum bit element for readout, each of which is configured using a Josephson parametric oscillator; a coupler that couples the information processing quantum bit device and the readout quantum bit device; Equipped with the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element; Information processing device.

[0176] (Appendix 2) The information processing quantum bit device is a computation quantum bit device, 10. The information processing device according to claim 1.

[0177] (Appendix 3) the readout quantum bit device and the calculation quantum bit device are coupled to each other, and the nonlinearity of the readout quantum bit device is smaller than the nonlinearity of the calculation quantum bit device; 3. The information processing device according to claim 2.

[0178] (Appendix 4) the readout qubit device and the computation qubit device, which are coupled to each other, are excited at the same frequency; 4. The information processing device according to claim 2 or 3.

[0179] (Appendix 5) a pump frequency of the computation qubit device is greater than twice the resonant frequency of the computation qubit device; the pump frequency of the readout quantum bit device is less than twice the resonant frequency of the readout quantum bit device; 5. An information processing device according to any one of appendices 2 to 4.

[0180] (Appendix 6) the coupled readout qubit device and the coupled computation qubit device are excited at the same pump frequency; the resonant frequency of the computational qubit device is less than one-half the pump frequency; the resonant frequency of the readout qubit device is greater than half the pump frequency; 4. The information processing device according to claim 2 or 3.

[0181] (Appendix 7) After the computation quantum bit device reaches a coherent state, the readout quantum bit device is excited. 7. An information processing device according to any one of appendices 2 to 6.

[0182] (Appendix 8) the computational quantum bit device and one or more four-body couplers among the couplers form an LHZ model; 8. An information processing device according to any one of appendices 2 to 7.

[0183] (Appendix 9) a control means for controlling an information processing device comprising an information processing quantum bit element, a readout quantum bit element, and a coupler for coupling the information processing quantum bit element and the readout quantum bit element, each of which is configured using a Josephson parametric oscillator, so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element; A control device comprising:

[0184] (Appendix 10) The information processing quantum bit device is a computation quantum bit device, 10. The control device according to claim 9.

[0185] (Appendix 11) the readout quantum bit device and the calculation quantum bit device are coupled to each other, and the nonlinearity of the readout quantum bit device is smaller than the nonlinearity of the calculation quantum bit device; 11. The control device of claim 10.

[0186] (Appendix 12) the control means excites the readout quantum bit device and the computation quantum bit device, which are coupled to each other, at the same frequency; 12. The control device of claim 10 or 11.

[0187] (Appendix 13) the control means controls the information processing device so that the pump frequency of the calculation quantum bit element becomes a value greater than twice the resonant frequency of the calculation quantum bit element, and the pump frequency of the readout quantum bit element becomes a value less than twice the resonant frequency of the readout quantum bit element. 13. The control device of any one of appendices 10 to 12.

[0188] (Appendix 14) the control means controls the information processing device so that the readout quantum bit element and the calculation quantum bit element, which are coupled to each other, are excited at the same pump frequency, the resonant frequency of the calculation quantum bit element is smaller than half the pump frequency, and the resonant frequency of the readout quantum bit element is larger than half the pump frequency. 12. The control device of claim 10 or 11.

[0189] (Appendix 15) the control means excites the readout quantum bit device after the computation quantum bit device reaches a coherent state; 15. The control device of any one of appendices 10 to 14.

[0190] (Appendix 16) the control means controls the information processing device in which the computational quantum bit device and one or more four-body couplers among the couplers form an LHZ model. 16. The control device of any one of appendices 10 to 15.

[0191] (Appendix 17) The information processing device is configured with a circuit including a plurality of quantum bit elements and a four-body coupler, in which an LHZ model, which is a model based on the LHZ method, is implemented in a circuit having a logic model with a larger number of bits than the problem being targeted by quantum computing, and the coupler is a four-body coupler; the control means controls the information processing device to operate one or more of the quantum bit elements as the computation quantum bit elements, to operate one or more of the quantum bit elements other than the computation quantum bit elements as the readout quantum bit elements, and to couple one of the readout quantum bit elements and one of the computation quantum bit elements in two-body coupling in each of the four-body couplers that couple the readout quantum bit elements with other quantum bit elements. 17. The control device of any one of appendices 10 to 16.

[0192] (Appendix 18) an information processing device; Control device and Equipped with The information processing device includes: a quantum bit element for information processing and a quantum bit element for readout, each of which is configured using a Josephson parametric oscillator; a coupler that couples the information processing quantum bit device and the readout quantum bit device; Equipped with The control device a control means for controlling the information processing device so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element; Equipped with Information processing system.

[0193] (Appendix 19) The information processing quantum bit device is a computation quantum bit device, 19. The information processing system of claim 18.

[0194] (Appendix 20) the readout quantum bit device and the calculation quantum bit device are coupled to each other, and the nonlinearity of the readout quantum bit device is smaller than the nonlinearity of the calculation quantum bit device; 19. The information processing system of claim 19.

[0195] (Appendix 21) the control means excites the readout quantum bit device and the computation quantum bit device, which are coupled to each other, at the same frequency; 21. The information processing system according to claim 19 or 20.

[0196] (Appendix 22) the control means controls the information processing device so that the pump frequency of the calculation quantum bit element becomes a value greater than twice the resonant frequency of the calculation quantum bit element, and the pump frequency of the readout quantum bit element becomes a value less than twice the resonant frequency of the readout quantum bit element. 22. An information processing system according to any one of appendices 19 to 21.

[0197] (Appendix 23) the control means controls the information processing device so that the readout quantum bit element and the calculation quantum bit element, which are coupled to each other, are excited at the same pump frequency, the resonant frequency of the calculation quantum bit element is smaller than half the pump frequency, and the resonant frequency of the readout quantum bit element is larger than half the pump frequency. 21. The information processing system according to claim 19 or 20.

[0198] (Appendix 24) the control means excites the readout quantum bit device after the computation quantum bit device reaches a coherent state; 24. The information processing system of any one of appendices 19 to 23.

[0199] (Appendix 25) the control means controls the information processing device in which the computational quantum bit device and one or more four-body couplers among the couplers form an LHZ model. 25. The information processing system of any one of appendices 19 to 24.

[0200] (Appendix 26) The information processing device is configured with a circuit including a plurality of quantum bit elements and a four-body coupler, in which an LHZ model, which is a model based on the LHZ method, is implemented in a circuit having a logic model with a larger number of bits than the problem being targeted by quantum computing, and the coupler is a four-body coupler; the control means controls the information processing device to operate one or more of the quantum bit elements as the computation quantum bit elements, to operate one or more of the quantum bit elements other than the computation quantum bit elements as the readout quantum bit elements, and to couple one of the readout quantum bit elements and one of the computation quantum bit elements in two-body coupling in each of the four-body couplers that couple the readout quantum bit elements with other quantum bit elements. 26. An information processing system according to any one of appendices 19 to 25.

[0201] (Appendix 27) a control device for controlling an information processing device including an information processing quantum bit element, a readout quantum bit element, and a coupler for coupling the information processing quantum bit element and the readout quantum bit element, each of which is configured using a Josephson parametric oscillator; The information processing device is controlled so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element. A control method comprising:

[0202] (Appendix 28) The information processing quantum bit device is a computation quantum bit device, 28. The control method of claim 27.

[0203] (Appendix 29) the readout quantum bit device and the calculation quantum bit device are coupled to each other, and the nonlinearity of the readout quantum bit device is smaller than the nonlinearity of the calculation quantum bit device; 29. The control method of claim 28.

[0204] (Appendix 30) controlling the information processing device includes exciting the readout quantum bit device and the computation quantum bit device, which are coupled to each other, at the same frequency; 29. The control method according to claim 28 or 29.

[0205] (Appendix 31) controlling the information processing device includes controlling the information processing device so that a pump frequency of the calculation quantum bit element is greater than twice the resonant frequency of the calculation quantum bit element, and a pump frequency of the readout quantum bit element is less than twice the resonant frequency of the readout quantum bit element; 31. The control method of any one of appendices 28 to 30.

[0206] (Appendix 32) controlling the information processing device includes controlling the information processing device so that the readout quantum bit device and the computation quantum bit device, which are coupled to each other, are excited at the same pump frequency, the resonant frequency of the computation quantum bit device is smaller than half the pump frequency, and the resonant frequency of the readout quantum bit device is larger than half the pump frequency. 29. The control method according to claim 28 or 29.

[0207] (Appendix 33) controlling the information processing device includes exciting the readout quantum bit device after the computation quantum bit device reaches a coherent state; 33. The control method of any one of appendices 28 to 32.

[0208] (Appendix 34) Controlling the information processing device includes controlling the information processing device in which the computational quantum bit device and one or more four-body couplers among the couplers form an LHZ model. 34. The control method of any one of appendices 28 to 33.

[0209] (Appendix 35) The information processing device is configured with a circuit including a plurality of quantum bit elements and a four-body coupler, in which an LHZ model, which is a model based on the LHZ method, is implemented in a circuit having a logic model with a larger number of bits than the problem being targeted by quantum computing, and the coupler is a four-body coupler; controlling the information processing device includes controlling the information processing device to operate one or more of the quantum bit elements as the computation quantum bit elements, operate one or more of the quantum bit elements other than the computation quantum bit elements as the readout quantum bit elements, and two-body couple one of the readout quantum bit elements and one of the computation quantum bit elements in each of the four-body couplers that couple the readout quantum bit element with another quantum bit element; 35. The control method of any one of appendices 28 to 34.

[0210] (Appendix 36) a computer that controls an information processing device that includes an information processing quantum bit device, a readout quantum bit device, and a coupler that couples the information processing quantum bit device and the readout quantum bit device, each of which is configured using a Josephson parametric oscillator; controlling the information processing device so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element; A program that executes the following.

[0211] (Appendix 37) The information processing quantum bit device is a computation quantum bit device, 36. The program described in Appendix 36.

[0212] (Appendix 38) the readout quantum bit device and the calculation quantum bit device are coupled to each other, and the nonlinearity of the readout quantum bit device is smaller than the nonlinearity of the calculation quantum bit device; 37. The program described in Appendix 37.

[0213] (Appendix 39) The control of the information processing device includes causing the computer to excite the readout quantum bit element and the calculation quantum bit element, which are coupled to each other, at the same frequency. 39. The program of claim 37 or 38.

[0214] (Appendix 40) controlling the information processing device includes causing the computer to control the information processing device so that a pump frequency of the calculation quantum bit element becomes a value greater than twice the resonant frequency of the calculation quantum bit element, and a pump frequency of the readout quantum bit element becomes a value less than twice the resonant frequency of the readout quantum bit element; 39. The program of claim 37.

[0215] (Appendix 41) controlling the information processing device includes causing the computer to control the information processing device so that the readout quantum bit element and the calculation quantum bit element, which are coupled to each other, are excited at the same pump frequency, the resonant frequency of the calculation quantum bit element is smaller than half the pump frequency, and the resonant frequency of the readout quantum bit element is larger than half the pump frequency; 39. The program of claim 37 or 38.

[0216] (Appendix 42) and controlling the information processing device includes causing the computer to excite the readout quantum bit device after the calculation quantum bit device reaches a coherent state. 42. The program of any one of appendices 37 to 41.

[0217] (Appendix 43) In controlling the information processing device, the computer is caused to control the information processing device in which the computational quantum bit device and one or more four-body couplers among the couplers form an LHZ model. 43. The program of any one of appendices 37 to 42.

[0218] (Appendix 44) The information processing device is configured with a circuit including a plurality of quantum bit elements and a four-body coupler, in which an LHZ model, which is a model based on the LHZ method, is implemented in a circuit having a logic model with a larger number of bits than the problem being targeted by quantum computing, and the coupler is a four-body coupler; controlling the information processing device includes causing the computer to control the information processing device so as to operate one or more of the quantum bit elements as the calculation quantum bit elements, operate one or more of the quantum bit elements other than the calculation quantum bit elements as the readout quantum bit elements, and cause each of the four-body couplers that couple the readout quantum bit elements with other quantum bit elements to couple one of the readout quantum bit elements with one of the calculation quantum bit elements in a two-body manner; 44. The program of any one of appendices 37 to 43. [Explanation of symbols]

[0219] 1,630 Information Processing Systems 100, 610, 631 Information processing equipment 110, 614, 637 qubit elements 110a Lumped constant quantum bit device 110b Distributed constant quantum bit device 111 Computational qubit elements 112, 612, 633 Readout quantum bit elements 120, 613, 634 combiner 121 Two-body combiner 122 4-body combiner 200, 620, 635 Control device 210, 621, 636 Control section 220 Observation Section 231 Communications Department 232 Display section 233 Operation input section 234 Storage section 235 Processing section 310 Superconducting quantum interference device 311 Josephson junction 320 inductor 330, 331, 332, 333 capacitors 340 λ / 4 resonator 351 Input end 352 Output end 353 Input / Output Terminal 611, 632 Quantum bit devices for information processing

Claims

1. a quantum bit element for information processing and a quantum bit element for readout, each of which is configured using a Josephson parametric oscillator; a coupler that couples the information processing quantum bit device and the readout quantum bit device; Equipped with the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element; Information processing device.

2. The information processing quantum bit device is a computation quantum bit device, The information processing device according to claim 1 .

3. the readout quantum bit device and the calculation quantum bit device are coupled to each other, and the nonlinearity of the readout quantum bit device is smaller than the nonlinearity of the calculation quantum bit device; The information processing device according to claim 2 .

4. the readout qubit device and the computation qubit device, which are coupled to each other, are excited at the same frequency; The information processing device according to claim 2 .

5. a pump frequency of the computation qubit device is greater than twice the resonant frequency of the computation qubit device; a pump frequency of the readout quantum bit device is less than twice the resonant frequency of the readout quantum bit device; The information processing device according to claim 2 .

6. the coupled readout qubit device and the coupled computation qubit device are excited at the same pump frequency; the resonant frequency of the computational qubit device is less than half the pump frequency; the resonant frequency of the readout quantum bit device is greater than half the pump frequency; The information processing device according to claim 2 .

7. After the computation quantum bit device reaches a coherent state, the readout quantum bit device is excited. The information processing device according to claim 2 .

8. a control means for controlling an information processing device comprising an information processing quantum bit element, a readout quantum bit element, and a coupler for coupling the information processing quantum bit element and the readout quantum bit element, each of which is configured using a Josephson parametric oscillator, so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element; A control device comprising:

9. an information processing device; Control device and Equipped with The information processing device includes: a quantum bit element for information processing and a quantum bit element for readout, each of which is configured using a Josephson parametric oscillator; a coupler that couples the information processing quantum bit device and the readout quantum bit device; Equipped with The control device a control means for controlling the information processing device so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element; Equipped with Information processing system.

10. a control device for controlling an information processing device including an information processing quantum bit element, a readout quantum bit element, and a coupler for coupling the information processing quantum bit element and the readout quantum bit element, each of which is configured using a Josephson parametric oscillator; The information processing device is controlled so that the readout quantum bit element is coupled to the information processing quantum bit element by the coupler so as to have the same bit value as the information processing quantum bit element. A control method comprising:

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