JP6853141B2 - Superconducting magnetic flux qubit controller - Google Patents

Description

The present invention realizes energy control of a superconducting magnetic flux qubit by applying microwaves.

Superconducting magnetic flux The energy of a qubit is controlled by the magnetic flux penetrating the loop. As a high-speed control method, a method in which a wide-band magnetic flux application line is prepared on the same chip as the superconducting magnetic flux qubit and a magnetic field is generated by the current flowing through the magnetic flux application line is often used.

Since this method uses an on-chip magnetic flux application line, it is essential to wire between the chip and the external control system, such as a superconducting flux qubit installed in a three-dimensional cavity resonator. It has been difficult to apply to superconducting flux qubits, which are structurally difficult to wire. Further, when controlling a plurality of superconducting flux qubits, there is a problem that the same number of magnetic flux application lines as those of the superconducting flux qubits are required (see Non-Patent Document 1).

F.G.Paauw, A.Fedorov, C.J.P.M Harmans, and J.E.Mooij, "Tuning the Gap of a Superconducting Flux Qubit", PHYSICAL REVIEW LETTERS, 102, 090501, 2009

The present invention has been made to solve the above problems, and provides a control device capable of high-speed energy control even for a superconducting flux qubit whose electrical wiring is structurally difficult. The purpose is.

The superconducting magnetic flux quantum bit controller of the present invention includes a first superconducting loop circuit including a first Josephson junction, a frequency variable resonator arranged in close proximity to the first superconducting loop circuit, and this frequency. The frequency variable resonator includes a microwave generator that applies microwaves to the variable resonator, the first superconducting loop circuit, and a magnetic field generator that applies a magnetic field to the frequency variable resonator. It is composed of a second superconducting loop circuit including a second Josephson junction and a centralized constant type resonance circuit connected to the second superconducting loop circuit, the first superconducting loop circuit and the above. A part of the second superconducting loop circuit is integrally formed, and the first superconducting loop circuit constitutes a superconducting magnetic flux quantum bit, and the energy of the superconducting magnetic flux quantum bit is transferred by the microwave. It is characterized by controlling.
Further, the superconducting magnetic flux quantum bit controller of the present invention includes a first superconducting loop circuit including a first Josephson junction, a frequency variable resonator arranged close to the first superconducting loop circuit, and the like. The frequency variable resonator includes a microwave generator that applies microwaves to the frequency variable resonator, the first superconducting loop circuit, and a magnetic field generator that applies a magnetic field to the frequency variable resonator. Is composed of a second superconducting loop circuit including a second Josephson junction and a distributed constant type resonance circuit connected to the second superconducting loop circuit, and is composed of the first superconducting loop circuit. And the second superconducting loop circuit are partially integrated, and the first superconducting loop circuit constitutes a superconducting magnetic flux quantum bit, and the energy of the superconducting magnetic flux quantum bit is transferred to the micro. It is characterized by being controlled by waves.

Further , in one configuration example of the superconducting flux qubit control device of the present invention, the microwave generator is characterized in that the frequency variable resonator is irradiated with the microwave.
Further, in one configuration example of the superconducting flux qubit control device of the present invention, the microwave generator supplies microwaves to the frequency variable resonator by supplying a microwave current to the distributed constant type resonant circuit. Is characterized by applying.

Further , in one configuration example of the superconducting magnetic flux quantum bit control device of the present invention, the second superconducting loop is located near the operating point of the superconducting magnetic flux quantum bit set by the magnetic field applied from the magnetic field generator. It is characterized in that the dimensions of the first and second superconducting loop circuits are set so that the inclination of the resonance angle frequency of the frequency variable resonator with respect to the magnetic flux penetrating the circuit becomes larger than 0. ..
Further, in one configuration example of the superconducting flux qubit control device of the present invention, the magnetic field is generated by detuning the energy of the superconducting flux qubit with respect to the energy in the state defined by the energy gap of the superconducting flux qubit. It is characterized in that it is positive or negative depending on the magnetic field applied from the device.

According to the present invention, the first superconducting loop circuit constituting the superconducting flux qubit and the frequency variable resonator are arranged close to each other to obtain mutual inductance between the first superconducting loop circuit and the frequency variable resonator. By increasing the size and applying a microwave to the frequency variable resonator, the energy of the superconducting flux qubit is controlled by the interaction between the superconducting flux qubit and the frequency variable resonator. This makes it possible to perform high-speed energy control even for a superconducting magnetic flux qubit, which is structurally difficult to electrically wire. Further, in the present invention, it is possible to perform energy control that suppresses decoherence due to crosstalk and noise inflow, which are problems when a control line is wired to each superconducting flux qubit.

FIG. 1 is a diagram showing a configuration of a superconducting magnetic flux qubit control device of the present invention. FIG. 2 is a diagram showing the magnetic flux dependence of the energy of the superconducting flux qubit of the present invention. FIG. 3 is a diagram showing a change in the resonance frequency of the frequency variable resonator of the present invention with respect to the magnetic flux penetrating the superconducting quantum interference element. FIG. 4 is a diagram showing a configuration of a superconducting magnetic flux qubit control device according to the first embodiment of the present invention. FIG. 5 is a diagram showing a change in the energy of the superconducting flux qubit with respect to the frequency of the microwave irradiating the frequency variable resonator in the first embodiment of the present invention. FIG. 6 is a diagram showing a change in the energy of the superconducting flux qubit with respect to the intensity of the microwave irradiating the frequency variable resonator in the first embodiment of the present invention. FIG. 7 is a diagram showing another configuration of the superconducting magnetic flux qubit control device according to the first embodiment of the present invention. FIG. 8 is a diagram showing a configuration of a superconducting magnetic flux qubit control device according to a second embodiment of the present invention.

[Differences between the features of the present invention and the prior art]
As shown in FIG. 1, the superconducting flux qubit control device of the present invention includes a frequency variable resonator 1 including a superconducting QUantum Interference Device (SQUID) 10 and a resonance circuit 11, and a frequency variable resonator. A microwave generator 2 that applies a microwave to 1, a superconducting flux qubit 3 to be controlled, a magnetic field generator 4 that applies a magnetic field to the superconducting flux qubit 3 and the frequency variable resonator 1. It is composed of.

In the present invention, the superconducting loop circuit 300 (first superconducting loop circuit) constituting the superconducting flux qubit 3 to be controlled and the superconducting loop circuit 100 (second superconducting loop) constituting the SQUID 10 By increasing the mutual inductance M with the circuit) and irradiating the frequency variable resonator 1 including the SQUID 10 with microwaves, the superconducting flux qubit 3 and the frequency variable resonator 1 interact with each other to generate the superconducting flux qubit 3. Energy control. The important point here is that energy control can be performed without directly controlling the magnetic flux penetrating the superconducting loop circuit 300 of the superconducting flux qubit 3.

The superconducting loop circuit 300 constituting the superconducting flux qubit 3 to be controlled has, for example, three Josephson junctions 301 (first Josephson junctions) in a loop-shaped superconductor. In the superconducting loop circuit 300, the energy detuning changes by changing the magnitude of the magnetic flux penetrating the loop. In the prior art, energy detuning is controlled by changing the magnetic flux penetrating the loop by passing a current through a magnetic flux application line installed on the same chip to generate a magnetic field. _{The Hamiltonian H q} of the superconducting flux qubit 3 can be written as follows.

Here, ε represents the energy detuning and Δ represents the energy gap. σ _x and σ _z are Pauli operators. The energy detuning ε has the following relationship _{with the magnetic flux Φ q penetrating the superconducting loop circuit 300.}

Here, I _p represents the permanent current of the superconducting magnetic flux qubit 3, and Φ ₀ = h / 2e represents the magnetic flux qubit. n is an arbitrary integer. Further, h is Planck's constant and e is an elementary charge. _{When the energy E q} of the superconducting magnetic flux qubit 3 is obtained from this Hamiltonian, it becomes as follows.

FIG. 2 is a diagram showing the magnetic flux dependence of the energy of the superconducting magnetic flux qubit 3. The horizontal axis of FIG. 2 is the magnetic flux penetrating the superconducting magnetic flux qubit 3 (superconducting loop circuit 300), and the vertical axis is the frequency of the superconducting magnetic flux qubit 3 ( _{value obtained by dividing the energy E q} by Planck's constant h). From the equation (3), it can be seen that the energy of the superconducting magnetic flux qubit 3 can be controlled by applying the magnetic flux.

As described above, the frequency variable resonator 1 is composed of the SQUAD 10 and the resonant circuit 11 connected to the SQUID 10. The superconducting loop circuit 100 constituting the SQUID 10 has, for example, two Josephson junctions 101 (second Josephson junctions) in the loop-shaped superconductor. The resonance circuit 11 is composed of a lumped constant type or distributed constant type resonance circuit composed of circuit elements such as an inductor and a capacitor. The inductance L _s of the SQUAD 10 changes as follows with _{respect to the magnetic flux Φ s} penetrating the superconducting loop circuit 100 constituting the SQUAD 10.

Here, I _c is the critical current of the Josephson junction 101 constituting the SQUID 10. Therefore, the resonator including the SQUID 10 acts as a frequency variable resonator 1 that can be controlled by a magnetic flux applied from the outside. FIG. 3 is a diagram showing how the resonance frequency of the frequency variable resonator 1 changes with respect to the magnetic flux penetrating the SQUID 10 (superconducting loop circuit 100). _{The Hamiltonian H r} of the frequency variable resonator 1 including the SQUID 10 can be described by the following equation.

Here, h'= h / 2π. ω (Φ _s ) is the central angle frequency of the frequency variable resonator 1 controlled by the magnetic flux penetrating the superconducting loop circuit 100. a and a ^† are photon annihilation operators and creation operators in the frequency variable resonator 1, respectively. The Hamiltonian H of the entire system composed of the superconducting magnetic flux qubit 3 and the frequency variable resonator 1 including the SQUID 10 is written as follows.

Here, the first term on the right side of the equation (6) is the Hamiltonian of the superconducting magnetic flux qubit 3, and the second term on the right side is the Hamiltonian of the frequency variable resonator 1 including the SQUID 10. The quantum state of the superconducting magnetic flux qubit 3 is composed of a current state | L (R)> flowing in the superconducting loop circuit 300 in the left (right) direction. Since the superconducting loop circuit 300 constituting the superconducting magnetic flux quantum bit 3 and the superconducting loop circuit 100 constituting the SQUID 10 of the frequency variable resonator 1 have a mutual inductance M, the current flowing through the superconducting loop circuit 300 is superconducting. _{The magnetic flux Φ S} passing through the loop circuit 100 is changed. Therefore, the center frequency of the frequency variable resonator 1 changes according to the quantum state of the superconducting magnetic flux qubit 3. The change in magnetic flux ΔΦ _{s in} this case can be described as follows.

For usually used flux of flux quantum [Phi ₀ about the size of the control variable frequency resonator 1, using about 1/1000 of the flux of the flux quantum [Phi ₀ to the control of a superconducting flux qubit 3 .. Therefore, within the range of energy control of the superconducting flux qubit 3 which is the object of the present invention, the frequency change of the frequency variable resonator 1 may be regarded as linear, and the Hamiltonian of the entire system is expanded in the range up to the first order. By doing so, it can be transformed as follows.

Here, Φ _s ⁰ is a magnetic flux penetrating the superconducting loop circuit 100 of SQUID 10 when there is no influence from the superconducting flux qubit 3, and 2 h'MI _p (dω / dΦ _s ) = δε. As can be seen from this equation, _{the value of the permanent current I p} of the superconducting flux qubit 3, the mutual inductance M between the superconducting flux qubit 3 and SQUID 10, and the gradient of the resonance angular frequency of the frequency variable resonator 1 dω / dΦ _s. By changing, the sensitivity of energy detuning to the number of photons a ^† a can be changed.

Further, the operating point of the superconducting flux qubit 3 is _{a magnetic flux near Φ 0} (n + 1/2), but in order to perform energy control by the method of the present invention, the resonance of the frequency variable resonator 1 is performed near the operating point. The element is designed so that the gradient dω / dΦ _{s of the angular frequency becomes large.} Specifically, the resonance angle of the frequency variable resonator 1 with respect _{to the magnetic flux Φ s} penetrating the superconducting loop circuit 100 near the operating point of the superconducting magnetic flux quantum bit 3 set by the external magnetic field applied from the magnetic field generator 4. The dimensions (areas) of the superconducting loop circuits 100 and 300 may be set so that the frequency gradient dω / dΦ _{s becomes larger than 0.}
When the energy eigenvalue E of the superconducting magnetic flux qubit 3 is obtained from the above Hamiltonian, it becomes as follows.

Here, the expected value <a ^† a> of the operator a ^† a is the number of photons in the frequency variable resonator 1. When the energy detuning ε and δε have the same sign, the energy detuning of the superconducting flux qubit 3 increases as the number of photons in the frequency variable resonator 1 increases. On the contrary, when the energy detuning ε and δε have different signs, the energy detuning of the superconducting flux qubit 3 decreases as the number of photons in the frequency variable resonator 1 increases.

Further, when the condition of | ε | >> Δ is satisfied in the equation (9), the energy eigenvalue E of the superconducting flux qubit 3 increases linearly with respect to the number of photons in the frequency variable resonator 1. The number of photons in the frequency variable resonator 1 can be adjusted by controlling the microwave irradiation amount.

By using the present invention as described above, the amount of microwave irradiation to the frequency variable resonator 1 is controlled, and the number of photons in the frequency variable resonator 1 is controlled to control the energy of the superconducting flux qubit 3. Is possible. Therefore, energy control can be performed only by propagating microwaves through space without using the magnetic flux application line used in the prior art. By utilizing this feature, it is possible to perform high-speed energy control even for a superconducting magnetic flux qubit, which is structurally difficult to wire.

Further, in the prior art, a control line was required for each superconducting flux qubit for energy control, whereas in the present invention, a frequency variable resonator 1 having a different resonance frequency is used for each superconducting flux qubit 3. By coupling to, the address of the superconducting flux qubit 3 to be controlled in the frequency space becomes possible. This makes it possible to control a plurality of superconducting magnetic flux qubits 3 by changing the frequency of microwave irradiation.

As a prior art, a method of controlling the energy of a superconducting flux qubit by using an AC stark shift with a non-variable frequency resonator is known (references "Alexandre Blais, Ren-Shou Huang, Andreas Wallraff, SMGirvin, and". RJSchoelkopf, “Cavity quantum electrodynamics for superconducting electrical circuits: An architecture for quantum computation”, PHYSICAL REVIEW A 69, 062320, 2004 ”). This method is effective when the resonance frequencies of the resonator and the superconducting flux qubit are relatively close (frequency difference is about several times to several tens of times the coupling constant g). The Hamiltonian of the coupling system of the frequency non-variable resonator and the superconducting flux qubit is described by the following equation.

Here, ω _q is the resonance angular frequency of the superconducting flux qubit, ω _r is the resonance frequency of the frequency non-variable resonator, and σ ₊ and σ _- are the ladder operators of the superconducting flux qubit. _{At this time, when the energy difference ω q} −ω _r between the frequency non-variable resonator and the superconducting flux qubit is sufficiently larger than the coupling constant g, the following distributed approximate Hamiltonian can be obtained.

Therefore, by feeding the microwaves photon frequency non-variable resonator by microwave irradiation, a superconducting flux quantum frequencies bits from ^{_{ω q ω q +2 {g 2}} / (ω q -ω r)} <a † It can be changed to a>. Here, <a ^† a> is the number of microwave photons in the frequency non-variable resonator. However, in the prior art, when g <a ^† _{a> becomes larger than the energy difference ω q} −ω _r between the frequency non-variable resonator and the superconducting flux qubit, the distributed approximation described above is broken. , Energy adjustment by AC Stark shift cannot be performed. Therefore, in the prior art, the energy adjustment by applying microwaves can be performed only on the order of several MHz to several tens of MHz.

On the other hand, since the present invention has no restrictions due to the distributed approximation of the prior art, it is possible to control the frequency of the superconducting flux qubit 3 on the order of GHz by using microwave application.

[First Example]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing a configuration of a superconducting magnetic flux qubit control device according to the first embodiment of the present invention. In this embodiment, an example in which energy control of a superconducting flux qubit is performed using a lumped constant LC resonator including SQUID is shown. The superconducting flux qubit control device of this embodiment includes a frequency variable resonator 1a including a SQUID 10a and a resonance circuit 11a, a microwave generator 2a, a superconducting flux qubit 3a, and a magnetic field generator 4. ing.

The superconducting loop circuit 100 constituting the SQUID 10a and the superconducting loop circuit 300 forming the superconducting flux qubit 3a are formed on the same substrate. In the example of FIG. 4, the superconducting loop circuit 300 is formed so as to be located inside the superconducting loop circuit 100 in the same plane as the superconducting loop circuit 100. Similar to FIG. 1, the superconducting loop circuit 100 constituting the SQUID 10a has, for example, two Josephson junctions 101 in the loop-shaped superconductor. The superconducting loop circuit 300 constituting the superconducting magnetic flux qubit 3a has, for example, three Josephson junctions 301 in the loop-shaped superconductor.

The resonance circuit 11a is a lumped constant type LC resonance circuit including a series circuit of the inductor L and the capacitor C. The frequency variable resonator 1a is configured by inserting the SQUID 10a in series with the inductor L and the capacitor C. That is, one end of the resonance circuit 11a (the terminal of the capacitor C in the example of FIG. 4) is connected to one point of the superconducting loop circuit 100, and the other end of the resonance circuit 11a (the terminal of the inductor L in the example of FIG. 4) is superconducting. It is connected to another point of the loop circuit 100.

The microwave generator 2a of the present embodiment includes a microwave irradiation antenna 200 that irradiates the frequency variable resonator 1a with microwaves, and a power supply (not shown) that supplies a microwave current to the microwave irradiation antenna 200. To.

A constant magnetic field is applied from the magnetic field generator 4 to the frequency variable resonator 1a and the superconducting magnetic flux qubit 3a. Here, the frequency is variable from the microwave generator 2a under the condition that the energy detuning ε is positive by the external magnetic field applied from the magnetic field generator 4 (magnetic flux Φ _{q = 0.5025 penetrating the superconducting loop circuit 300).} FIG. 5A shows the energy of the superconducting magnetic flux quantum bit 3a when the resonator 1a is irradiated with a microwave. Further, under the condition that the energy detuning ε is negative due to the external magnetic field applied from the magnetic field generator 4 (magnetic flux Φ _q = 0.4975 penetrating the superconducting loop circuit 300), the frequency variable resonance from the microwave generator 2a FIG. 5B shows the energy of the superconducting magnetic flux quantum bit 3a when the vessel 1a is irradiated with a microwave. The horizontal axis of FIGS. 5A and 5B is the frequency of the microwave irradiating the frequency variable resonator 1a, and the vertical axis is the frequency of the superconducting flux qubit 3a (energy E _q divided by Planck's constant h). Value).

In FIG. 5A, when the microwave applied to the frequency variable resonator 1a resonates with the frequency variable resonator 1a (~ 3.5 GHz), that is, when the number of microwave photons in the frequency variable resonator 1a increases, it becomes super. It can be seen that the resonance frequency of the conduction magnetic flux quantum bit 3a is increasing from about 5.3 GHz. Further, in FIG. 5B, it can be seen that as the number of microwave photons in the frequency variable resonator 1a increases, the resonance frequency of the superconducting flux qubit 3a decreases from about 5.2 GHz. That is, it can be seen that the energy of the superconducting magnetic flux qubit 3a can be controlled in the positive or negative direction by the positive or negative of the energy detuning ε.

Similar to the above, under the condition that the energy detuning ε is positive by the external magnetic field applied from the magnetic field generator 4 (magnetic flux Φ _q = 0.5025), the microwave generator 2a is directed to the frequency variable resonator 1a. FIG. 6A shows the energy of the superconducting magnetic flux quantum bit 3a when the number of photons in the frequency variable resonator 1a is controlled by adjusting the intensity of the microwave to be irradiated. Further, the frequency variable resonator 1a is irradiated from the microwave generator 2a under the condition that the energy detuning ε is negative (magnetic flux Φ _{q = 0.4975) by the external magnetic field applied from the magnetic field generator 4.} FIG. 6B shows the energy of the superconducting magnetic flux quantum bit 3a when the number of photons in the frequency variable resonator 1a is controlled by adjusting the intensity of the microwave. The horizontal axis of FIGS. 6 (A) and 6 (B) is the intensity of the microwave irradiating the frequency variable resonator 1a, and the vertical axis is the frequency of the superconducting flux qubit 3a (energy E _q divided by Planck's constant h). Value).

According to FIGS. 6A and 6B, the frequency is variable in a region where the energy detuning ε is sufficiently large with respect to the energy gap Δ (for example, the energy detuning ε is 3 times or more with respect to the energy gap Δ). It can be seen that the energy of the superconducting flux qubit 3a can be controlled linearly with respect to the number of photons in the resonator 1a. It is also found that the energy of the superconducting magnetic flux qubit 3a can be changed by 1 GHz or more, unlike the conventional method using AC Stark shift.

In this embodiment, an example in which the superconducting loop circuit 100 constituting the SQUID 10a and the superconducting loop circuit 300 constituting the superconducting flux qubit 3a are formed separately has been described, but the present invention is not limited to this. Instead, as shown in FIG. 7, the superconducting loop circuit 100 and a part of the superconducting loop circuit 300 may be integrated. The place to be integrated may be any place as long as the Josephson joints 101 and 301 are not formed. By integrating a part of the superconducting loop circuit 100 and the superconducting loop circuit 300, the mutual inductance M of the superconducting loop circuit 100 and the superconducting loop circuit 300 can be increased.

[Second Example]
Next, a second embodiment of the present invention will be described. FIG. 8 is a diagram showing a configuration of a superconducting magnetic flux qubit control device according to a second embodiment of the present invention. In this embodiment, an example in which energy control of a superconducting magnetic flux qubit is performed using a distributed constant type transmission line resonator including SQUID is shown. The superconducting flux qubit control device of this embodiment includes a frequency variable resonator 1b including a SQUID 10b and a resonance circuit 11b, a microwave generator 2b, a superconducting flux qubit 3b, and a magnetic field generator 4. ing.

The superconducting loop circuit 100 constituting the SQUID 10b and the superconducting loop circuit 300 forming the superconducting flux qubit 3b are formed on the same substrate. Similar to FIG. 4, in the example of FIG. 8, the superconducting loop circuit 300 is formed so as to be located inside the superconducting loop circuit 100 in the same plane as the superconducting loop circuit 100.

The resonant circuit 11b is a distributed constant type transmission line resonant circuit composed of a 1/4 wavelength coplanar waveguide CPW and a capacitor C2 configured by arranging a plurality of distributed constant lines in an interdigital manner. The frequency variable resonator 1b is configured by inserting the SQUID 10b in series with the coplanar waveguide CPW and the capacitor C2. One end of the resonant circuit 11b (one end of the coplanar waveguide CPW in the example of FIG. 8) is connected to one point of the superconducting loop circuit 100, and the other end of the resonant circuit 11b (the terminal of the capacitor C2 in the example of FIG. 8) is a microwave. It is connected to the generator 2b. Further, another point of the superconducting loop circuit 100 is grounded.

The microwave generator 2b of this embodiment applies a microwave to the frequency variable resonator 1b by supplying a microwave current to the other end of the resonance circuit 11b.

The parameters of the element such as the mutual inductance M can be changed variously depending on the design, but when the same parameters as those in the first embodiment are used, the superconducting magnetic flux when a microwave is applied to the frequency variable resonator 1b. The behavior of the quantum bit 3b is the same as that of the first embodiment (FIGS. 5 (A), 5 (B), 6 (A), 6 (B)). Therefore, even when the distributed constant type resonance circuit 11b is used, the energy of the superconducting magnetic flux qubit 3b can be changed by 1 GHz or more.

In this embodiment as well, similarly to the first embodiment, a part of the superconducting loop circuit 100 constituting the SQUID 10b and the superconducting loop circuit 300 constituting the superconducting flux qubit 3b are integrated to form a superconducting loop. The mutual inductance M of the circuit 100 and the superconducting loop circuit 300 may be increased.

The present invention can be applied to a technique for controlling the energy of a superconducting magnetic flux qubit.

1,1a, 1b ... Frequency variable resonator, 2,2a, 2b ... Microwave generator, 3,3a, 3b ... Superconducting flux qubit, 4 ... Magnetic field generator, 10,10a, 10b ... Superconducting quantum interference Elements, 11, 11a, 11b ... Resonant circuit, 100, 300 ... Superconducting loop circuit, 101, 301 ... Josephson junction, 200 ... Microwave irradiation antenna, L ... inductor, C, C2 ... Capacitor, CPW ... Coplanar waveguide ..

Claims (6)

A first superconducting loop circuit, including a first Josephson junction,
This first superconducting loop circuit and the frequency variable resonator placed in close proximity to it,
A microwave generator that applies microwaves to this variable frequency resonator,
It includes the first superconducting loop circuit and a magnetic field generator that applies a magnetic field to the frequency variable resonator.
The frequency variable resonator is
A second superconducting loop circuit, including a second Josephson junction,
It is composed of this second superconducting loop circuit and a lumped constant type resonant circuit connected to it.
The first superconducting loop circuit and the second superconducting loop circuit are partially integrally formed.
The first superconducting loop circuit constitutes a superconducting flux qubit, and is a superconducting flux qubit control device characterized in that the energy of the superconducting flux qubit is controlled by the microwave. A first superconducting loop circuit, including a first Josephson junction,
This first superconducting loop circuit and the frequency variable resonator placed in close proximity to it,
A microwave generator that applies microwaves to this variable frequency resonator,
It includes the first superconducting loop circuit and a magnetic field generator that applies a magnetic field to the frequency variable resonator.
The frequency variable resonator is
A second superconducting loop circuit, including a second Josephson junction,
It is composed of this second superconducting loop circuit and a distributed constant type resonant circuit connected to it.
The first superconducting loop circuit and the second superconducting loop circuit are partially integrally formed.
The first superconducting loop circuit constitutes a superconducting flux qubit, and is a superconducting flux qubit control device characterized in that the energy of the superconducting flux qubit is controlled by the microwave. In the superconducting magnetic flux qubit control device according to claim 1.
The microwave generator is a superconducting magnetic flux qubit control device characterized by irradiating the frequency variable resonator with the microwave. In the superconducting magnetic flux qubit control device according to claim 2.
The microwave generator is a superconducting flux qubit control device, characterized in that a microwave is applied to the frequency variable resonator by supplying a microwave current to the distributed constant type resonant circuit. In the superconducting magnetic flux qubit control device according to any one of claims 1 to 4.
In the vicinity of the operating point of the superconducting magnetic flux quantum bit set by the magnetic field applied from the magnetic field generator, the inclination of the resonance angle frequency of the frequency variable resonator with respect to the magnetic flux penetrating the second superconducting loop circuit is 0. A superconducting magnetic flux quantum bit control device, characterized in that the dimensions of the first and second superconducting loop circuits are set so as to be larger. In the superconducting magnetic flux qubit control device according to any one of claims 1 to 5.
The superconducting flux qubit is characterized in that the energy detuning of the superconducting flux qubit with respect to the energy in the state defined by the energy gap of the superconducting flux qubit is positive or negative depending on the magnetic field applied from the magnetic field generator. Conductive flux qubit controller.

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