Calculation device

Abstract

To simplify a hardware configuration of an arithmetic device.SOLUTION: An Ising model arithmetic device 1 includes a plurality of parametric resonant circuits 2, a plurality of wiring 3, and a plurality of interaction circuits 4. The parametric resonant circuit 2 includes a coil 12 and a time-varying capacitor 13. The plurality of parametric resonant circuits 2 are configured to resonate at a preset resonant frequency. The plurality of wiring 3 connect a first parametric resonance circuit and a second parametric resonance circuit, and at least one wiring is provided for each of the plurality of parametric resonance circuits 2. The plurality of interaction circuits 4 are arranged on an energization path formed by the wiring 3 and configured to set interaction between the first and the second parametric resonance circuits.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a computing device that executes computations that simulate an Ising model. [Background technology]

[0002] The Ising machine developed by D-WAVE, a Canadian company, is known as a computing device that uses the Ising model to solve combinatorial optimization problems (see, for example, Non-Patent Document 1). This Ising machine achieves 2000-bit parallel calculations by utilizing a special spin that appears only in the superconducting state. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Hidetoshi Nishimori, "Current Status and Prospects of Quantum Annealing," Journal of the Institute of Electrical, Information and Communication Engineers, vol. 103, No. 3, pp. 264-266. 2020 Summary of the Invention [Problem to be solved by the invention]

[0004] The Ising machine described in Non-Patent Document 1 requires an extremely low temperature of −270° C. or less in order to utilize a physical phenomenon that occurs only in a superconducting state, and the device becomes large, limiting its uses.

[0005] The present disclosure aims to simplify the hardware configuration of a computing device that simulates an Ising model. [Means for solving the problem]

[0006] One aspect of the present disclosure is a computing device that performs calculations using an Ising model, and includes a plurality of resonant circuits, a plurality of wirings, and a plurality of interaction circuits, and the resonant circuits include at least a coil and a capacitor.

[0007] The plurality of resonant circuits are configured to resonate at preset resonant frequencies. The plurality of wirings connect the first resonant circuit and the second resonant circuit, and at least one wiring is provided for each of the plurality of resonant circuits. The first resonant circuit is any one of the plurality of resonant circuits. The second resonant circuit is one of the plurality of resonant circuits that is different from the first resonant circuit.

[0008] The plurality of interaction circuits are arranged on a current path formed by the plurality of wirings, respectively, and are configured to set an interaction between the first resonant circuit and the second resonant circuit.

[0009] The computing device of the present disclosure configured in this manner can set the oscillation phase in the multiple resonant circuits to 0 [rad] or π [rad], thereby setting the spin of the Ising model for each of the multiple resonant circuits to "up spin" or "down spin," thereby simulating the spin direction of the Ising model. Furthermore, since the computing device of the present disclosure can simulate the spin direction of the Ising model using multiple resonant circuits, it can operate at room temperature and does not require a special cooling device. Therefore, the computing device of the present disclosure can simplify the hardware configuration of the computing device. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an Ising model calculation device according to a first embodiment. [Figure 2] 1A and 1B are a circuit diagram of a parametric resonant circuit, a circuit diagram of a time-varying capacitor, and a graph showing the reverse bias voltage dependence of the capacitance of the time-varying capacitor; [Figure 3] 10 is a graph showing a simulation result of oscillation of a parametric resonant circuit. [Figure 4] FIG. 1 is a circuit diagram showing a configuration of an interaction circuit according to a first embodiment. [Figure 5] FIG. 1 is a diagram illustrating an Ising model composed of three spins. [Figure 6] This is a diagram showing the calculated energies for all three spin combinations. [Figure 7] FIG. 1 is a circuit diagram showing the configuration of an Ising model calculation device that simulates an Ising model composed of three spins. [Figure 8] 10 is a graph showing the simulation results of oscillation of three parametric resonant circuits that constitute the Ising model calculation device. [Figure 9] FIG. 10 is a diagram showing the time change of energy and spin distribution in an Ising model calculation device. [Figure 10] FIG. 10 is a diagram illustrating a schematic configuration of an Ising model calculation device according to a second embodiment. [Figure 11] FIG. 10 is a circuit diagram showing the configuration of an interaction circuit according to a second embodiment. [Figure 12] FIG. 10 is a diagram illustrating an Ising model according to a second embodiment. [Figure 13] 10 is a table showing energies calculated for all combinations of three spins in the second embodiment. [Figure 14] 10 is a graph showing simulation results of oscillation of three parametric resonant circuits in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] A first embodiment of the present disclosure will be described below with reference to the drawings. The Ising model calculation device 1 of this embodiment is configured by arranging a plurality of parametric resonant circuits 2 in a two-dimensional lattice pattern, as shown in Fig. 1. In the Ising model calculation device 1 of this embodiment, ten parametric resonant circuits 2 are arranged along the horizontal direction D1, and ten parametric resonant circuits 2 are arranged along the vertical direction D2.

[0012] 2, the parametric resonant circuit 2 includes a resistor 11, a coil 12, and a time-varying capacitor 13. The parametric resonant circuit 2 has a resonant frequency ω cIt is an RLC parallel circuit.

[0013] The parametric resonant circuit 2 has a first terminal 14 and a second terminal 15. The first terminal 14 is connected to a first end of the resistor 11, a first end of the coil 12, and a first end of the time-varying capacitor 13. The second terminal 15 is connected to a second end of the resistor 11, a second end of the coil 12, and a second end of the time-varying capacitor 13.

[0014] The time-varying capacitor 13 includes variable capacitance diodes 21, 22, 23, and 24, a DC power supply 25, an AC power supply 26, a first terminal 27, and a second terminal . The anode of the variable capacitance diode 21 is connected to the cathode of the variable capacitance diode 23. The cathode of the variable capacitance diode 21 is connected to the cathode of the variable capacitance diode 22.

[0015] The anode of the variable capacitance diode 22 is connected to the cathode of the variable capacitance diode 24. The anode of the variable capacitance diode 23 is connected to the anode of the variable capacitance diode 24.

[0016] A positive electrode 25a of DC power supply 25 is connected to a connection point 13a between the cathode of variable capacitance diode 21 and the cathode of variable capacitance diode 22. A negative electrode 25b of DC power supply 25 is connected to a first output terminal 26a of AC power supply 26. A second output terminal 26b of AC power supply 26 is connected to a connection point 13b between the anode of variable capacitance diode 23 and the anode of variable capacitance diode 24.

[0017] The first terminal 27 is connected to a connection point 13c between the anode of the variable capacitance diode 22 and the cathode of the variable capacitance diode 24. The second terminal 28 is connected to a connection point 13d between the anode of the variable capacitance diode 21 and the cathode of the variable capacitance diode 23.

[0018] As shown in graph G1 of FIG. 2, the capacitance of time-varying capacitor 13 changes in response to the reverse bias voltage applied between connection points 13a and 13b. In the RLC parallel circuit, parametric oscillation occurs when the parameters of the resonant system are changed over time. The strongest parametric oscillation occurs when the parameters are changed over time at twice the resonant angular frequency. The AC power supply 26 generates a parametric oscillation at a resonant angular frequency ω c (i.e., 2ω c ) the voltage changes at the resonant angular frequency ω c The capacitance changes periodically at an angular frequency twice that of the

[0019] Specifically, when the capacitance C(t) of the time-varying capacitor 13 is changed by C0(1+2Γsin2ωt) (i.e., by changing the amplitude 2ΓC0 and the angular frequency 2ω around C0), the 2 >1 / Q 2 +δ 2 " is established, parametric oscillation occurs. Here, Q=R×(L / C)1 / 2, δ=1-ω c 2 / ω 2 In order to make oscillation easier, the resistance value of the resistor 11 is usually set to be sufficiently large, and ω is set to a resonant angular frequency ω c To do so.

[0020] The parametric resonant circuit 2 can set the oscillation phase to 0 [rad] by grounding the first terminal 14 and setting the initial voltage of the second terminal 15 to a positive value (e.g., +1 V), and can set the oscillation phase to π [rad] by setting the initial voltage of the second terminal 15 to a negative value (e.g., -1 V). The initial voltage is continuously applied until a predetermined time (e.g., 100 μs) has elapsed since the start of operation of the parametric resonant circuit 2. In other words, when the predetermined time has elapsed since the start of operation of the parametric resonant circuit 2, the application of the initial voltage is stopped.

[0021] Figure 3 is a graph showing the results of simulating the voltage change of the parametric resonant circuit 2 using LTspice. LTspice is software that simulates the operation of electronic circuits. LTspice is a registered trademark.

[0022] The simulation results shown in graph G2 were obtained by making the initial voltage positive, and the simulation results shown in graph G3 were obtained by making the initial voltage negative. Curves L21 and L31 in graphs G2 and G3 indicate the change over time in the output voltage of the AC power supply 26. Curves L22 and L32 in graphs G2 and G3 indicate the change over time in the output voltage between the first terminal 14 and the second terminal 15 in the parametric resonant circuit 2.

[0023] Graph G2 shows the simulation results when the oscillation phase of the parametric resonant circuit 2 is 0 [rad]. Graph G3 shows the simulation results when the oscillation phase of the parametric resonant circuit 2 is π [rad].

[0024] As shown in graphs G2 and G3, the simulation confirmed that when the excitation angular frequency is 2ω, oscillation occurs with an angular frequency of ω and a phase of 0 [rad] or π [rad]. Furthermore, when the oscillation is stopped, damped oscillation occurs as in a normal RLC circuit, and the phase state is maintained.

[0025] Therefore, the spin direction of the Ising model can be simulated by the oscillation of the parametric resonant circuit 2. That is, oscillation with a phase of 0 [rad] is defined as "upward spin," and oscillation with a phase of π [rad] is defined as "downward spin."

[0026] As shown in FIG. 1, a plurality of parametric resonant circuits 2 constituting an Ising model calculation device 1 are each connected to adjacent parametric resonant circuits 2 via wiring 3 .

[0027] For example, the parametric resonant circuit 2a is adjacent to the parametric resonant circuit 2d and the parametric resonant circuit 2e along the horizontal direction D1, and is adjacent to the parametric resonant circuit 2b and the parametric resonant circuit 2c along the vertical direction D2.

[0028] The parametric resonator circuit 2a is connected to the parametric resonator circuit 2b via the wiring 3b. Similarly, the parametric resonator circuit 2a is connected to the parametric resonators 2c, 2d, and 2e via the wirings 3c, 3d, and 3e.

[0029] The ends of the wirings 3b, 3c, 3d, and 3e that are not connected to the parametric resonant circuits 2b, 2c, 2d, and 2e are connected to a connection point Pa. The second terminal 15 of the parametric resonant circuit 2a is connected to the connection point Pa. The first terminal 14 of the parametric resonant circuit 2a is grounded.

[0030] Moreover, an interaction circuit 4 is disposed on the current path formed by each of the plurality of wires 3. 4, the interaction circuit 4 includes resistors 31 and 32, a switch 33, a first terminal 34, and a second terminal 35. In this embodiment, the resistance value R of the resistors 31 and 32 is 50 kΩ.

[0031] A first end of resistor 31 is connected to first terminal 34. A second end of resistor 31 is connected to a first end of switch 33. A second end of switch 33 is connected to a first end of resistor 32. A second end of resistor 32 is connected to second terminal 35.

[0032] Next, the Ising model will be described. The Ising model is a statistical mechanical model that describes the behavior of spin in a magnetic material. In the Ising model, the energy H of a magnetic material is expressed by the Hamiltonian shown in equation (1).

[0033]

number

[0034] σ in Equation (1) i and σ j are the i-th and j-th spins, respectively. σ i and σ jcan have a value of +1 or -1, where "+1" indicates an upspin and "-1" indicates a downspin.

[0035] J in Equation (1) ij is a coefficient that indicates the strength of the interaction between the ith spin and the jth spin. Note that the condition for a ferromagnetic material is J ij >0, and the condition for an antiferromagnet is J ij <0.

[0036] Here, we consider the Ising model M1, which consists of three spins σ1, σ2, and σ3, as shown in Figure 5. The Ising model M1 uses J 12 =J 23 =J 31 Set =+1.

[0037] For example, in the Ising model M1 in Fig. 5, σ1 = +1, σ2 = +1, and σ3 = -1. Therefore, the energy H of the magnetic material is +1, as shown in equation (2). H=-(J 12 σ1σ2+J 23 σ2σ3+J 31 σ3σ1) =-{(+1)+(-1)+(-1)}=+1 (2) The energy H calculated in this way for all combinations of σ1, σ2, and σ3 is shown in Figure 6.

[0038] As shown in Figure 6, when σ1=σ2=σ3=-1 and when σ1=σ2=σ3=+1, the energy H=-3. On the other hand, when there are other spin combinations, the energy H=+1. Therefore, the optimal solutions (i.e., the ground state) are when σ1=σ2=σ3=-1 and when σ1=σ2=σ3=+1.

[0039] An Ising model calculation device 101 shown in FIG. 7 simulates the Ising model M1 in FIG. The Ising model calculation device 101 includes parametric resonant circuits 102, 103, and 104, three wires 105, 106, and 107, and interaction circuits 108, 109, and 110.

[0040] Like the parametric resonant circuit 2, the parametric resonant circuits 102, 103, and 104 are RLC parallel circuits including a resistor 11, a coil 12, a time-varying capacitor 13, a first terminal 14, and a second terminal 15.

[0041] The parametric resonant circuit 102 and the parametric resonant circuit 103 are connected to each other via a wiring 105. The parametric resonant circuit 103 and the parametric resonant circuit 104 are connected to each other via a wiring 106. The parametric resonant circuit 104 and the parametric resonant circuit 102 are connected to each other via a wiring 107.

[0042] The second terminal 15 of the parametric resonant circuit 102 is connected to a connection point 101a between the first end of the wiring 105 and the second end of the wiring 107. The second terminal 15 of the parametric resonant circuit 103 is connected to a connection point 101b between the second end of the wiring 105 and the first end of the wiring 106. The second terminal 15 of the parametric resonant circuit 104 is connected to a connection point 101c between the second end of the wiring 106 and the first end of the wiring 107.

[0043] Furthermore, the first terminals 14 of the parametric resonant circuits 102, 103, and 104 are grounded. The interaction circuits 108, 109, and 110 are the same as the interaction circuit 4. The interaction circuits 108, 109, and 110 are arranged on the current paths formed by the wirings 105, 106, and 107, respectively.

[0044] 8 is a graph showing the results of a simulation using LTspice of voltage changes in the parametric resonant circuits 102, 103, and 104 in the Ising model calculation device 101. Curves L41, L42, and L43 of graph G4 represent the time changes in the output voltages of the parametric resonant circuits 102, 103, and 104, respectively.

[0045] As shown in FIG. 8, when the time is between 0 and 10 μs, the phase of oscillation of the parametric resonant circuit 102 is π [rad], and the phases of oscillation of the parametric resonant circuits 103 and 104 are 0 [rad].

[0046] Then, at 15 μs, the excitation by the AC power supply 26 is stopped and the switches 33 of the interaction circuits 108, 109, and 110 are turned on, causing interaction to occur among the parametric resonant circuits 102, 103, and 104. As a result, the phase of oscillation of the parametric resonant circuits 102, 103, and 104 becomes 0 [rad]. Therefore, the Ising model calculation device 101 can reproduce the transition in the ferromagnetic material from a state where σ1 = +1, σ2 = +1, and σ3 = -1 (i.e., a high-energy state) to a state of the minimum value (H = -3) where σ1 = +1, σ2 = +1, and σ3 = +1 (i.e., the ground state).

[0047] Next, the results of simulating the time change of the energy H in the Ising model calculation device 1 and the time change of the spin distribution in the Ising model calculation device 1 using LTspice will be described.

[0048] As shown in graph G5 in FIG. 9, at the start of the simulation (i.e., at 0 μs), the energy H is close to 0. Then, at about 80 μs, the energy H becomes about −150. Finally, the energy H becomes the minimum value (i.e., about −180).

[0049] Spin distributions SD1, SD2, SD3, SD4, and SD5 in FIG. 9 indicate the spin distributions of the Ising model calculation device 1 at points P1, P2, P3, P4, and P5 on the graph G5, respectively.

[0050] In the spin distributions SD1 to SD5, 10 squares are arranged along the horizontal direction D1 and 10 squares are arranged along the vertical direction D2, so that a total of 100 squares are arranged in a two-dimensional matrix. Each of the 100 squares corresponds to one parametric resonator circuit 2.

[0051] In the spin distributions SD1 to SD5, hatched squares have a spin of +1, and unhatched squares have a spin of -1. As shown in the spin distribution SD1, at the start of the simulation (i.e., at 0 μs), the number of squares with a spin of +1 is almost the same as the number of squares with a spin of -1. In this embodiment, the initial settings were 53 squares with a spin of +1 and 47 squares with a spin of -1. Furthermore, at 23 μs, the switch 33 of the interaction circuit 4 was turned on to start the calculation.

[0052] Thereafter, as shown in the spin distributions SD2 to SD5, the number of squares with a spin of +1 increases as time passes, and eventually, all squares have a spin of +1. Therefore, the Ising model calculation device 1 can reproduce the properties of a ferromagnetic material.

[0053] The Ising model calculation device 1 configured in this manner executes calculations using the Ising model, and includes a plurality of parametric resonant circuits 2, a plurality of wirings 3, and a plurality of interaction circuits 4. The parametric resonant circuit 2 includes at least a coil 12 and a time-varying capacitor 13.

[0054] The plurality of parametric resonant circuits 2 are connected to each other at a predetermined resonant angular frequency ω c The oscillator is configured to resonate at a frequency of 1000 kHz. The plurality of wirings 3 connect the first parametric resonant circuit and the second parametric resonant circuit, and at least one wiring 3 is provided for each of the plurality of parametric resonant circuits 2.

[0055] The first parametric resonant circuit is any one of the multiple parametric resonant circuits 2. The second parametric resonant circuit is one of the multiple parametric resonant circuits 2 that is different from the first parametric resonant circuit. For example, as shown in FIG. 1, if the parametric resonant circuit 2a is the first parametric resonant circuit, the second parametric resonant circuits are the parametric resonant circuits 2b, 2c, 2d, and 2e. The wirings 3b, 3c, 3d, and 3e are wirings 3 provided for the parametric resonant circuit 2a.

[0056] The plurality of interaction circuits 4 are arranged on the current path formed by the plurality of wirings 3 for each of the plurality of wirings 3, and are configured to set up an interaction between the first parametric resonant circuit and the second parametric resonant circuit.

[0057] Such an Ising model calculation device 1 can set the spin of the Ising model to "upward spin" or "downward spin" for each of the multiple parametric resonant circuits 2 by setting the phase of oscillation in the multiple parametric resonant circuits 2 to 0 [rad] or π [rad], thereby simulating the spin direction of the Ising model. Since the Ising model calculation device 1 can simulate the spin direction of the Ising model using the multiple parametric resonant circuits 2, it can operate at room temperature and does not require a special cooling device. Therefore, the Ising model calculation device 1 can simplify its hardware configuration.

[0058] The interaction circuit 4 also includes at least resistors 31 and 32, and a switch 33 connected in series to the resistors 31 and 32. This allows the Ising model calculation device 1 to reproduce the properties of a ferromagnetic material.

[0059] In the above-described embodiment, the Ising model calculation device 1 corresponds to a calculation device, and the resonance angular frequency ω ccorresponds to the resonant frequency, the parametric resonant circuit 2 corresponds to the resonant circuit, and the time-varying capacitor 13 corresponds to the capacitor.

[0060] [Second embodiment] A second embodiment of the present disclosure will be described below with reference to the drawings. In the second embodiment, only the parts that are different from the first embodiment will be described. The same reference numerals will be used to designate common components.

[0061] The Ising model calculation device 201 of the second embodiment includes parametric resonant circuits 202, 203, and 204, wirings 205, 206, and 207, and interaction circuits 208, 209, and 210.

[0062] Like the parametric resonant circuit 2, the parametric resonant circuits 202, 203, and 204 are RLC parallel circuits including a resistor 11, a coil 12, a time-varying capacitor 13, a first terminal 14, and a second terminal 15.

[0063] The parametric resonant circuit 202 and the parametric resonant circuit 203 are connected to each other via a wiring 205. The parametric resonant circuit 203 and the parametric resonant circuit 204 are connected to each other via a wiring 206. The parametric resonant circuit 204 and the parametric resonant circuit 202 are connected to each other via a wiring 207.

[0064] The second terminal 15 of the parametric resonant circuit 202 is connected to a connection point 201a between the first end of the wiring 205 and the second end of the wiring 207. The second terminal 15 of the parametric resonant circuit 203 is connected to a connection point 201b between the second end of the wiring 205 and the first end of the wiring 206. The second terminal 15 of the parametric resonant circuit 204 is connected to a connection point 201c between the second end of the wiring 206 and the first end of the wiring 207.

[0065] Furthermore, the first terminals 14 of the parametric resonant circuits 202, 203, and 204 are grounded. 11, the interaction circuit 208 is identical to the interaction circuit 4. The interaction circuits 209 and 210 include resistors 41 and 42, switches 43 and 44, a time delay circuit 45, a first terminal 46, and a second terminal 47.

[0066] A first end of the resistor 41 is connected to the first terminal 46. A second end of the resistor 41 is connected to a first end of the switch 43. A second end of the switch 43 is connected to a first end of the time delay circuit 45.

[0067] A second terminal of the time delay circuit 45 is connected to a first terminal of the switch 44. A second terminal of the switch 44 is connected to a first terminal of the resistor 42. A second terminal of the resistor 42 is connected to a second terminal 47.

[0068] In this embodiment, the resistance value Rn of the resistors 41 and 42 is 50 kΩ. Antiferromagnets have properties opposite to those of ferromagnets. Therefore, an antiferromagnet can be expressed by delaying the signal propagation time between two adjacent parametric resonator circuits 2 by half a period. Therefore, the delay time of the time delay circuit 45 is set to half the resonant period of the parametric resonator circuits 2.

[0069] The resistance values ​​of resistors 41 and 42 are equal to each other. The characteristic impedance Z0 of the time delay circuit 45 is set to be equal to the resistance value Rn of resistors 41 and 42 in order to suppress signal reflection. In this embodiment, the delay time Td of the time delay circuit 45 is 3.846 μs.

[0070] As a result, the interaction circuits 209 and 210 detect the strength of the interaction (i.e., J ij <0).

[0071] As shown in FIG. 10, the interaction circuits 208, 209, and 210 are arranged on the current paths formed by the wirings 205, 206, and 207, respectively. The Ising model calculation device 201 simulates the Ising model M2 shown in FIG.

[0072] As shown in Figure 12, the Ising model M2 is 12 =J 31 =-1, J 23 Set =+1. For example, in the Ising model M2 in Fig. 12, σ1 = +1, σ2 = +1, and σ3 = -1. Therefore, the energy H of the magnetic material is +1, as shown in equation (3).

[0073] H=-(J 12 σ1σ2+J 23 σ2σ3+J 31 σ3σ1) =-{(-1)+(-1)+(+1)}=+1 (3) The energy H calculated in this way for all combinations of σ1, σ2, and σ3 is shown in FIG.

[0074] As shown in Figure 13, when σ1 = -1, σ2 = σ3 = +1 and when σ1 = +1, σ2 = σ3 = -1, the energy H = -3. On the other hand, when there are other spin combinations, the energy H = +1. Therefore, the optimal solutions (i.e., the ground state) are when σ1 = -1, σ2 = σ3 = +1 and when σ1 = +1, σ2 = σ3 = -1.

[0075] 14 is a graph showing the results of a simulation using LTspice of voltage changes in the parametric resonant circuits 202, 203, and 204 in the Ising model calculation device 201. Curves L61, L62, and L63 of graph G6 represent the time changes in the output voltages of the parametric resonant circuits 202, 203, and 204, respectively.

[0076] As shown in FIG. 14, when the time is between 0 and 20 μs, the phase of oscillation of the parametric resonant circuit 202 is π [rad], and the phases of oscillation of the parametric resonant circuits 203 and 204 are 0 [rad].

[0077] Then, at 20 μs, the excitation by the AC power supply 26 is stopped, and the switch 33 of the interaction circuit 208 and the switches 43 and 44 of the interaction circuits 209 and 210 are turned on, causing an interaction to occur between the parametric resonant circuits 202, 203, and 204. As a result, the phase of oscillation of the parametric resonant circuits 202 and 203 becomes π [rad], and the phase of oscillation of the parametric resonant circuit 204 becomes 0 [rad]. Therefore, the Ising model calculation device 201 can reproduce a transition from a state where σ1 = +1, σ2 = +1, and σ3 = -1 (i.e., a high-energy state) to a state of the minimum value (H = -3) where σ1 = +1, σ2 = -1, and σ3 = -1 (i.e., the ground state).

[0078] In such an Ising model calculation device 201, the interaction circuits 209, 210 include at least a time delay circuit 45 and switches 43, 44 connected in series to the time delay circuit 45. This allows the Ising model calculation device 201 to reproduce the properties of an antiferromagnetic material.

[0079] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and can be implemented in various modifications. [Variation 1] For example, in the above embodiment, a configuration in which a plurality of parametric resonant circuits 2 are arranged in a two-dimensional lattice pattern has been shown, but they may also be arranged in a three-dimensional lattice pattern. Furthermore, the arrangement is not limited to a lattice pattern, and it is sufficient if a plurality of parametric resonant circuits 2 are arranged and connected via wiring 3.

[0080] [Variation 2] In the above embodiment, the time-varying capacitor 13 has a resonant angular frequency ω c However, the period in which the capacitance of the time-varying capacitor 13 changes is twice the resonant angular frequency ω c is not limited to twice the resonant angular frequency ω c It is sufficient if it is an integer multiple (including the frequency error δ).

[0081] [Variation 3] In the second embodiment described above, a configuration was shown in which an interaction circuit 4 including resistors 31 and 32 and a switch 33 and an interaction circuit 4 including resistors 41 and 42, switches 43 and 44, and a time delay circuit 45 are mixed. However, depending on the Ising model to be simulated, it is possible to freely switch between an interaction circuit 4 that sets ferromagnetic interaction (i.e., J>0) and an interaction circuit 4 that sets antiferromagnetic interaction (i.e., J<0).

[0082] [Variation 4] In the above embodiment, the inductance of the coil is fixed and the temporal change in the capacitance of the capacitor is utilized to realize parametric oscillation of the parametric resonant circuit 2. However, parametric oscillation can also be realized by fixing the capacitance of the capacitor of the parametric resonant circuit 2 and utilizing the temporal change in the inductance of the coil.

[0083] In the above embodiments, multiple functions of one component may be realized by multiple components, or one function of one component may be realized by multiple components. Furthermore, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0084] 1,201...Ising model calculation device, 2,202,203,204...Parametric resonant circuit, 3,205,206,207...Wiring, 4,208,209,210...Interaction circuit, 12...Coil, 13...Time-varying capacitor

Claims

[Claim 1] A computing device that performs a computation using an Ising model, a plurality of resonant circuits configured to resonate at preset resonant frequencies; a plurality of wirings, at least one of which is provided for each of the plurality of resonant circuits, connecting the first resonant circuit and the second resonant circuit, with any one of the resonant circuits being a first resonant circuit and another resonant circuit different from the first resonant circuit being a second resonant circuit; a plurality of interaction circuits, each of which is arranged on a current path formed by the wiring and configured to set an interaction between the first resonant circuit and the second resonant circuit, for each of the plurality of wirings; the resonant circuit includes at least a coil and a capacitor; The interaction circuit is an arithmetic device including at least a time delay circuit and a switch connected in series to the time delay circuit.

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