CN111598248B - Superconducting quantum chip and method for realizing control of phase gate - Google Patents
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Abstract
The invention discloses a superconducting quantum chip design scheme for realizing control of a phase gate and a gate operation method. The superconducting quantum chip comprises a plurality of conductors arranged on a chip bottom plateThe superconducting quantum chip comprises a plurality of quantum bits, wherein each quantum bit is provided with a quantum bit, each quantum bit is connected with a superconducting quantum interference device, each quantum bit is connected with a frequency modulation control line, the frequency of each quantum bit is higher than that of the corresponding superconducting quantum chip, and the circuit design of the superconducting quantum chip meets the following requirements:the invention has the advantages of small operation error, high fidelity and strong robustness.
Description
Technical Field
The invention relates to the field of superconducting quantum computation, in particular to a superconducting quantum chip and a method for realizing control of a phase gate.
Background
High quality quantum gate operation is a key indicator of quantum processors, determining whether quantum computers can take advantage of quantum advantages. The high-fidelity quantum gate operation can also effectively reduce the bit number required by quantum error correction and improve the effect of quantum simulation. The main gate operating error in the current quantum systems is derived from two-bit gates. The highest reported two-bit gate fidelity is known to be around 99.5% [1-2], so improving the two-bit gate operating scheme, improving fidelity is the primary task to achieve large-scale quantum computation.
In general, door operation errors originate mainly from three parts: decoherence of qubits, non-ideal interactions in gate operating schemes (including parasitic coupling, state leakage), and perturbation of system control parameters. (1) decoherence: bit decoherence is unavoidable due to the coupling of the qubit to the external environment, although in recent years the decoherence time of superconducting qubits has been greatly improved (on the order of hundreds of microseconds) [3-4], decoherence is still the main source of gate operating errors. Decoherence of qubits is a random error, generally determined by chip and system noise, and is difficult to improve on control schemes. Reducing the time of the gate operation is the most straightforward and efficient method in the case of a certain bit lifetime. (2) parasitic coupling and state leakage: taking the widely used transmitter (Transmon) type qubit as an example [5], the non-harmony is low (10-30 times of the bit frequency), the energy levels are close (the coupling between the energy levels is more complex in the case of multiple bits), and in the microwave control, the frequency spectrum of the pulse signal is widened along with the reduction of the operation time of the gate, so that the state leakage is difficult to avoid. The two-bit gate operation also needs to consider the crosstalk between signals during multi-bit control, and the crosstalk is difficult to completely eliminate whether the frequency modulation scheme [6-8] or the full microwave control scheme [9] is adopted. In addition, frequency crowding (Frequency Crowding) is also a problem that needs to be addressed in mid-scale quantum processors. (3) fluctuation of system parameters: fluctuations in the control parameters are a factor that is easily ignored, and fluctuations in the system parameters are unavoidable in actual experimental operations. Many door operating schemes theoretically achieve very high fidelity (greater than 99.9%), and door operating times are short, but door operation is very parameter sensitive (less robust). As the door operation depth increases, the robustness of the system is important. Insulation is an important solution to improve robustness, but it often requires a long enough evolution time, and how to accelerate insulation is an important research direction [7,10-15].
In summary, high quality two-bit gate operation should satisfy three conditions: the gate operation time is short, the theoretical fidelity is high enough under the incoherent condition without consideration, and certain robustness is achieved.
In the prior art, an indirect coupling scheme for realizing bits through an adjustable coupler is known, wherein the bits realize state conversion through virtual photons in the coupler, and states cannot leak into the coupler in an evolution process. The advantage of this scheme over frequency modulation schemes that do not use couplers is that the effects of parasitic coupling can be effectively eliminated, fundamentally solving the frequency crowding problem. Google and IBM have adopted different schemes to implement such two-bit gates [1,9]. In the Google scheme, two quantum bits serving as basic calculation units are modulated to a resonance state, the coupling strength among the bits can be changed by adjusting the frequency of a coupler, the coupling is closed at a specific frequency point, the state conversion is not carried out, and when two-bit gate operation is needed, the frequency of the coupler is changed, the coupling is opened, and the state exchange is realized. This solution can theoretically achieve very high fidelity and faster door operation, but in practical experiments, there is a problem of magnetic flux crosstalk, and thus door operation errors are still large. In the IBM scheme, the bit frequency is not adjustable, and the quantum state exchange is realized by performing parameter modulation on the coupler, so that the scheme can avoid the influence of magnetic flux crosstalk, and can obtain longer decoherence time, but the gate operation speed is slower, and under the condition of emphasis, part of states leak into the coupler, so that the gate operation error is still larger.
Disclosure of Invention
The invention aims to: aiming at the problem of large gate operation error in the prior art, the invention provides a superconducting quantum chip and a method for realizing control of a phase gate, and the gate operation error is small and the fidelity is high.
The technical scheme is as follows: the superconducting quantum chip for realizing the phase gate control comprises a plurality of transmission sub-quantum bits arranged on a chip bottom plate, wherein an adjustable coupler is further arranged between every two adjacent quantum bits, the adjustable coupler comprises a capacitor and a superconducting quantum interferometer, the capacitor is grounded through the superconducting quantum interferometer and is connected with a frequency modulation control line, the frequency of the adjustable coupler is far higher than the frequency of the quantum bits, and the circuit design of the superconducting quantum chip meets the following conditions:
in the formula g 12 Represents the coupling strength between two adjacent qubits g 1c 、g 2c Respectively represent the coupling strength between two adjacent qubits and the adjustable coupler, delta 1c 、Δ 2c Representing the amount of detuning between the frequency of two adjacent qubits and the tunable coupler frequency, respectively.
Further, each qubit comprises a capacitor and a Josephson junction, the capacitor is grounded through the Josephson junction and is connected with a driving control line, the capacitor of the qubit is cross-shaped, the capacitor of the adjustable coupler is I-shaped, and the cross-shaped protrusion of the capacitor of the qubit is matched with the I-shaped recess of the capacitor of the adjustable coupler to form a shape of 'Ten-Ten … …'.
Further, the frequency range of the adjustable coupler is 6-9GHz, the frequency range of the quantum bit is 4.5-5 GHz, at least 300HZ is arranged between the frequencies of every two adjacent quantum bits, the coupling strength between the quantum bits and the coupler is 100-200MHz, the coupling strength between the quantum bits is 4-10MHz, and the frequency of the quantum bits is fixed.
Furthermore, the adjustable coupler realizes frequency adjustment through the magnetic flux bias pulse signal input in the frequency modulation control line, and the input magnetic flux bias pulse signal is in the following adiabatic waveform:
wherein w is c (t) shows the waveform of the input magnetic flux bias pulse signal, w 1 The frequency of a higher one of two adjacent qubits is represented, θ (t) represents a phase angle parameter related to the amplitude of an input magnetic flux bias pulse signal, t 0 、t f Representing the start time and end time of the quantum gate operation, θ i Is the phase angle parameter when the coupling is closed, and the corresponding amplitude is 0 and theta f Representing the maximum phase angle during modulation, corresponding to the maximum modulation amplitude.
The method for realizing the control of the phase gate comprises the following steps:
(1) Setting a superconducting quantum chip: arranging a plurality of transmission sub-quantum bits on a chip base plate, and arranging an adjustable coupler between every two adjacent quantum bits, wherein the adjustable coupler comprises a capacitor and a superconducting quantum interferometer, and the capacitor is grounded and connected with a frequency modulation control line through the superconducting quantum interferometer;
(2) Setting the frequency of the tunable coupler to be much higher than the frequency of the qubit;
(3) Adjusting the circuit design of the superconducting quantum chip so as to satisfy the following conditions:
in the formula g 12 Represents the coupling strength between two adjacent qubits g 1c 、g 2c Respectively represent the coupling strength between two adjacent qubits and the adjustable coupler, delta 1c 、Δ 2c Representing the amount of detuning between the frequency of two adjacent qubits and the tunable coupler frequency, respectively.
Further, each qubit comprises a capacitor and a Josephson junction, the capacitor is grounded through the Josephson junction and is connected with a driving control line, the capacitor of the qubit is cross-shaped, the capacitor of the adjustable coupler is I-shaped, and the cross-shaped protrusion of the capacitor of the qubit is matched with the I-shaped recess of the capacitor of the adjustable coupler to form a shape of 'Ten-Ten … …'.
Further, the frequency range of the adjustable coupler is 6-9GHz, the frequency range of the quantum bit is 4.5-5 GHz, at least 300HZ is arranged between the frequencies of every two adjacent quantum bits, the coupling strength between the quantum bits and the coupler is 100-200MHz, the coupling strength between the quantum bits is 4-10MHz, and the frequency of the quantum bits is fixed.
Furthermore, the adjustable coupler realizes frequency adjustment through the magnetic flux bias pulse signal input in the frequency modulation control line, and the input magnetic flux bias pulse signal is in the following adiabatic waveform:
wherein w is c (t) shows the waveform of the input magnetic flux bias pulse signal, w 1 Represents the frequency of the higher one of the adjacent two qubits, and θ (t) represents a phase angle parameter related to the amplitude of the input magnetic flux bias pulse signal，t 0 、t f Representing the start time and end time of the quantum gate operation, θ i Is the phase angle parameter when the coupling is closed, and the corresponding amplitude is 0 and theta f Representing the maximum phase angle during modulation, corresponding to the maximum modulation amplitude.
The beneficial effects are that: compared with the prior art, the invention has the remarkable advantages that: the operation error is small, the fidelity is high, and the robustness is strong.
Drawings
FIG. 1 is a schematic diagram of a superconducting quantum chip provided by the present invention;
FIG. 2 is a graph of the relationship between coupler and qubit combined frequency difference and coefficient k and zz coupling;
FIG. 3 is a plot of intensity of ZZ coupling versus frequency difference between the coupler and the qubit;
FIG. 4 is a schematic diagram of the frequency bands of a qubit and coupler;
FIG. 5 is a graph of intensity of ZZ coupling versus frequency of the coupler versus qubit;
FIG. 6 is a phase angle θ of the conditional phase (conditional phase) with gate operating time and pulse amplitude f Is a variation of (2);
fig. 7 shows the error rate of the door operation according to the present embodiment as a function of the duration of the door operation, and the circles and diamonds correspond to the fidelity of the insulated door and the non-insulated door, respectively.
Detailed Description
The present embodiment provides a superconducting quantum chip for implementing phase gate control, as shown in fig. 1, including a plurality of transmission sub-quantum bits (transmon) disposed on a chip substrate and adjustable couplers (couplers) disposed between every two adjacent quantum bits, each quantum bit including a cross capacitor and a josephson junction (X number shown in fig. 1), the cross capacitor being grounded through the josephson junction and connected to a driving control line (XY line shown in fig. 1), each adjustable coupler including an i-shaped capacitor and a superconducting quantum interferometer, the i-shaped capacitor being grounded through the superconducting quantum interferometer and connected to a frequency modulation control line (Z line shown in fig. 1), the superconducting quantum interferometer (SQUID) being formed by two josephson junctions in parallel, the protrusions of the cross capacitor of the quantum bits being matched with the i-shaped capacitor recesses of the adjustable couplers to form a shape of "ten-industry … …", so that the indirect coupling of the quantum bits is implemented, and the arrangement is convenient for wiring and interference can be reduced. Each quantum bit is connected with a driving control line to realize single-bit gate operation, and each adjustable coupler is modulated by externally-applied magnetic flux bias pulse signals to realize frequency adjustment.
The circuit design of the superconducting quantum chip in this embodiment satisfies:wherein subscripts 1, 2, c respectively denote two adjacent qubits and an adjustable coupler, g 12 Represents the coupling strength between two adjacent qubits g 1c 、g 2c Respectively represent the coupling strength between two adjacent qubits and the adjustable coupler, delta 1c 、Δ 2c Representing the amount of detuning between the frequency of two adjacent qubits and the tunable coupler frequency, respectively. The thought of the design is as follows: in order to improve fidelity and reduce gate operating errors, the ZZ coupling of the chip is required to be high-contrast, namely: 1. when no magnetic flux bias signal is applied, ZZ coupling should be closed sufficiently, otherwise, the system is equivalent to a continuous and tiny control phase gate, and the fidelity of a single-bit gate is affected; 2. the ZZ coupling needs to be fully opened when the magnetic flux bias signal is applied, and at this time, the higher the ZZ coupling strength, the faster the door operation speed can be. Consider a three-bit system hamiltonian H:
wherein, superscriptRepresenting hermite conjugate operators, e.g. a i And->Representing the generation and annihilation operators in quantum mechanics, w, respectively i Respectively represent the frequency of the corresponding device, alpha i Representing non-harmony of the corresponding device, and approximately calculating the intensity relation of ZZ coupling by using a fourth-order perturbation theory:
wherein delta is 1c ＝w 1 -w c ,Δ 2c ＝w 2 -w c K is a dimensionless coefficient determined by the capacitance in the line. By simulation, it was found that with a specific k-factor, a ZZ coupling of height ratio can be achieved, as shown in fig. 2. In fig. 2, the light areas indicate that the ZZ coupling is turned off (or modulated to a small value), and the dark areas indicate that the ZZ coupling is turned on. When the value of k is between 3 and 4, high contrast ZZ coupling can be achieved, and the value also accords with the following theoretical expectation:
the formula implies g 12 And g 1c 、g 2c The dispersion relation between them is approximatelyThat is, the condition is satisfied, and the ZZ coupling with high contrast can be realized. Comparing the scheme of this embodiment with the scheme of using adjustable bits conventionally, as shown in fig. 3, it can be seen that this embodiment has a ZZ coupling with a higher contrast, and under the same condition of the maximum ZZ coupling, this embodiment can better close the coupling in the dispersion area.
To solve the frequency crowding and interference problems common in mid-scale chips, the frequencies of the adjacent two qubits and tunable couplers of this embodiment are prepared in three frequency bands, as shown in fig. 4. The tunable coupler has a frequency in the highest frequency band (e.g., 6-9 GHz) that is much higher than the frequency band of the qubits (e.g., 4.5GHz-5 GHz) to reduce the indirect effects of flux noise in the coupler on bit decoherence. The frequencies of two adjacent qubits are alternately placed in two similar frequency bands with a minimum separation (about 300 MHz) between the two frequency bands to reduce parasitic coupling between neighboring bits and non-resonant state transitions between bits during gate operation. The coupling strength between the qubit and the coupler is 100-200MHz, and the coupling strength between the qubit and the coupler is 4-10MHz. For example, one qubit frequency may be set to 4.8GHz-5GHz and the other to 4.5GHz-4.7GHz, with dark and light colors representing qubits of different frequencies in FIG. 1. The service life of the quantum bit can be prolonged by using the non-tunable frequency quantum bit, and the bit can be prepared to be tunable in frequency.
The working principle of the chip of the embodiment is as follows: by modulating the frequency of the tunable coupler, the intensity of the ZZ coupling between the qubits is changed, see black line in fig. 5, and when the frequency of the coupler is much higher than the qubit frequency (i.e., the coupler is operating in the dispersive region), the ZZ coupling is turned off, and by applying a flux bias pulse (flux pulse), the frequency of the coupler can be modulated near the qubit, at which time the ZZ coupling is turned on, as shown by the light line in fig. 5. During the pulse modulation, the phase continues to accumulate over the two bits of the 11 state, i.e., the conditional phase (conditional phase), due to the action of the ZZ coupling. The modulation amplitude and duration are changed, so that the phase accumulation amount can be changed, and when the phase accumulation is equal to 180 degrees, a control phase gate is formed, namely, the control phase gate is realized through switch coupling.
The error of the door operation mainly includes two parts: decoherence and control errors. The parameters such as waveform, intensity and the like of the magnetic flux bias pulse signal input into the adjustable coupler play a decisive role in controlling errors. The adoption of the insulated door can improve the robustness of door operation and reduce control errors, but the change of Hamiltonian amount of the insulated door in the prior art is slow enough, namely the door operation time is long enough. In view of this problem, this embodiment is improved by providing an adiabatic waveform that can simultaneously ensure faster speed and improve the fidelity of two-bit gate operation, specifically:
wherein w is c (t) shows the waveform of the input magnetic flux bias pulse signal, w 1 The frequency of a higher one of two adjacent qubits is represented, θ (t) represents a phase angle parameter related to the amplitude of an input magnetic flux bias pulse signal, t 0 、t f Representing the start time and end time of the quantum gate operation, θ i Is the phase angle parameter when the coupling is closed, and the corresponding amplitude is 0 and theta f Representing the maximum phase angle during modulation. θ f Determining maximum pulse amplitude by varying θ f A specific conditional phase may be obtained as shown in fig. 6.
The fidelity of the control phase gate at different gate operating times was simulated, as shown in fig. 7, with the error rate of the thermal isolation gate theoretically being very small (< 1 e-5), even in the case of a relatively short gate operating time (< 50 ns). The insulated door defined in this solution has significant advantages compared to the usual non-insulated doors. It can be seen that the insulated gate of this embodiment can simultaneously ensure a faster speed and improve the fidelity of the two-bit gate operation.
The embodiment also provides a method for realizing the control of the phase gate, which comprises the following steps:
(1) Setting a superconducting quantum chip: arranging a plurality of transmission sub-quantum bits on a chip base plate, and arranging an adjustable coupler between every two adjacent quantum bits, wherein the adjustable coupler comprises a capacitor and a superconducting quantum interferometer, and the capacitor is grounded and connected with a frequency modulation control line through the superconducting quantum interferometer; each qubit comprises a capacitor and a Josephson junction, the capacitor is grounded through the Josephson junction and is connected with a driving control line, the capacitor of the qubit is cross-shaped, the capacitor of the adjustable coupler is I-shaped, and the cross-shaped protrusion of the capacitor of the qubit is matched with the I-shaped recess of the capacitor of the adjustable coupler to form a shape of 'Ten-work … …'.
(2) Setting the frequency of the tunable coupler to be much higher than the frequency of the qubit; the method comprises the following steps: the frequency range of the adjustable coupler is 6-9GHz, the frequency range of the quantum bit is 4.5-5 GHz, at least 300HZ is arranged between the frequencies of every two adjacent quantum bits, the coupling strength between the quantum bits and the coupler is 100-200MHz, and the coupling strength between the quantum bits is 4-10MHz.
(3) Adjusting the circuit design of the superconducting quantum chip so as to satisfy the following conditions:
in the formula g 12 Represents the coupling strength between two adjacent qubits g 1c 、g 2c Respectively represent the coupling strength between two adjacent qubits and the adjustable coupler, delta 1c 、Δ 2c Representing the amount of detuning between the frequency of two adjacent qubits and the tunable coupler frequency, respectively.
Furthermore, the adjustable coupler realizes frequency adjustment through the magnetic flux bias pulse signal input in the frequency modulation control line, and the input magnetic flux bias pulse signal is in the following adiabatic waveform:
wherein w is c (t) shows the waveform of the input magnetic flux bias pulse signal, w 1 The frequency of a higher one of two adjacent qubits is represented, θ (t) represents a phase angle parameter related to the amplitude of an input magnetic flux bias pulse signal, t 0 、t f Representing the start time and end time of the quantum gate operation, θ i Is the phase angle parameter when the coupling is closed, and the corresponding amplitude is 0 and theta f Representing the maximum phase angle during modulation, corresponding to the maximum modulation amplitude.
The method of this embodiment corresponds to the above-mentioned devices one by one, and reference is not made to the above-mentioned devices for details, and details are not repeated.
In summary, the quantum bit decoherence performance of the embodiment (1) is better: the quantum bit which is not adjustable in frequency is not influenced by magnetic flux noise, so that longer decoherence time is realized; (2) fast door operation speed and high fidelity: generally, increasing the door operating speed may result in lower fidelity. In an embodiment scheme, due to strong coupling of bits with the coupler, faster gate operation does not introduce excessive gate operation errors; (3) robust door operation: adiabatic operation makes the quantum gate more robust, which is the greatest advantage of the adiabatic scheme.
[ reference ] to
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Claims (8)
1. The utility model provides a superconductive quantum chip of realization control phase gate, includes a plurality of fixed transmission sub-qubits of frequency of arranging on the chip bottom plate, its characterized in that: an adjustable coupler is further arranged between every two adjacent quantum bits, the adjustable coupler comprises a capacitor and a superconducting quantum interferometer, the capacitor is grounded and connected with a frequency modulation control line through the superconducting quantum interferometer, the frequency of the adjustable coupler is far higher than that of the quantum bits, and the circuit design of the superconducting quantum chip meets the following conditions:
in the formula g 12 Represents the coupling strength between two adjacent qubits g 1c 、g 2c Respectively represent the coupling strength between two adjacent qubits and the adjustable coupler, delta 1c 、Δ 2c Representing the amount of detuning between the frequency of two adjacent qubits and the tunable coupler frequency, respectively.
2. The superconducting quantum chip for realizing the control of the phase gate according to claim 1, wherein: each qubit comprises a capacitor and a Josephson junction, the capacitor is grounded through the Josephson junction and is connected with a driving control line, the capacitor of the qubit is cross-shaped, the capacitor of the adjustable coupler is I-shaped, and the cross-shaped protrusion of the capacitor of the qubit is matched with the I-shaped recess of the capacitor of the adjustable coupler to form a shape of 'Ten-work … …'.
3. The superconducting quantum chip for realizing the control of the phase gate according to claim 1, wherein: the frequency range of the adjustable coupler is 6-9GHz, the frequency range of the quantum bit is 4.5-5 GHz, at least 300MHz is spaced between the frequencies of every two adjacent quantum bits, the coupling strength between the quantum bits and the coupler is 100-200MHz, the coupling strength between the quantum bits is 4-10MHz, and the frequency of the quantum bits is fixed.
4. The superconducting quantum chip for realizing the control of the phase gate according to claim 1, wherein: the adjustable coupler realizes frequency adjustment through the magnetic flux bias pulse signal input in the frequency modulation control line, and the input magnetic flux bias pulse signal is in the following adiabatic waveform:
wherein w is c (t) shows the waveform of the input magnetic flux bias pulse signal, w 1 The frequency of a higher one of two adjacent qubits is represented, θ (t) represents a phase angle parameter related to the amplitude of an input magnetic flux bias pulse signal, t 0 、t f Representing the start time and end time of the quantum gate operation, θ i Is the phase angle parameter when the coupling is closed, and the corresponding amplitude is 0 and theta f Representing the maximum phase angle during modulation, corresponding to the maximum modulation amplitude.
5. A method for implementing a control phase gate, comprising:
(1) Setting a superconducting quantum chip: arranging a plurality of transmission sub-quantum bits on a chip base plate, and arranging an adjustable coupler between every two adjacent quantum bits, wherein the adjustable coupler comprises a capacitor and a superconducting quantum interferometer, and the capacitor is grounded and connected with a frequency modulation control line through the superconducting quantum interferometer;
(2) Setting the frequency of the tunable coupler to be much higher than the frequency of the qubit;
(3) Adjusting the circuit design of the superconducting quantum chip so as to satisfy the following conditions:
in the formula g 12 Represents the coupling strength between two adjacent qubits g 1c 、g 2c Respectively represent the coupling strength between two adjacent qubits and the adjustable coupler, delta 1c 、Δ 2c Representing the amount of detuning between the frequency of two adjacent qubits and the tunable coupler frequency, respectively.
6. The method for implementing a phase gate control of claim 5, wherein: each qubit comprises a capacitor and a Josephson junction, the capacitor is grounded through the Josephson junction and is connected with a driving control line, the capacitor of the qubit is cross-shaped, the capacitor of the adjustable coupler is I-shaped, and the cross-shaped protrusion of the capacitor of the qubit is matched with the I-shaped recess of the capacitor of the adjustable coupler to form a shape of 'Ten-work … …'.
7. The method for implementing a phase gate control of claim 5, wherein: the frequency range of the adjustable coupler is 6-9GHz, the frequency range of the quantum bit is 4.5-5 GHz, at least 300HZ is spaced between the frequencies of every two adjacent quantum bits, the coupling strength between the quantum bits and the coupler is 100-200MHz, the coupling strength between the quantum bits is 4-10MHz, and the frequency of the quantum bits is fixed.
8. The method for implementing a phase gate control of claim 5, wherein: the adjustable coupler realizes frequency adjustment through a magnetic flux bias pulse signal input in the frequency modulation control line, wherein the input magnetic flux bias pulse signal is in the following adiabatic waveform:
wherein w is c (t) represents inputWaveform of magnetic flux bias pulse signal, w 1 The frequency of a higher one of two adjacent qubits is represented, θ (t) represents a phase angle parameter related to the amplitude of an input magnetic flux bias pulse signal, t 0 、t f Representing the start time and end time of the quantum gate operation, θ i Is the phase angle parameter when the coupling is closed, and the corresponding amplitude is 0 and theta f Representing the maximum phase angle during modulation, corresponding to the maximum modulation amplitude.
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| EP3992867A1 (en) * | 2020-10-30 | 2022-05-04 | IQM Finland Oy | Tunable coupler with coupling extension |
| CN112331693B (en) * | 2020-11-02 | 2023-08-29 | 深圳市福田区南科大量子技术与工程研究院 | Easily-expanded high-fidelity superconducting quantum chip structure and operation method |
| CN114429215A (en) * | 2022-01-28 | 2022-05-03 | 中国科学技术大学 | Method for realizing double-bit quantum gate based on superconducting quantum coupler |
| CN114492820A (en) * | 2022-01-28 | 2022-05-13 | 中国科学技术大学 | Microwave pulse optimization method |
| CN115470923B (en) * | 2022-08-22 | 2024-04-05 | 本源量子计算科技（合肥）股份有限公司 | Method and device for acquiring DC spectrum of adjustable coupler and quantum computer |
| US20240095564A1 (en) * | 2022-09-15 | 2024-03-21 | International Business Machines Corporation | Generating dc offsets in flux-tunable transmons with persistent current loops |
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| CN105957832A (en) * | 2016-05-12 | 2016-09-21 | 中国科学院物理研究所 | Wiring method of superconducting quantum bit system for surface coding scheme and wiring board |
| CN108475353A (en) * | 2015-12-31 | 2018-08-31 | 国际商业机器公司 | Using the muliti-qubit adjustable coupling structure of fixed frequency superconductive quantum bit |
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| CN105957832A (en) * | 2016-05-12 | 2016-09-21 | 中国科学院物理研究所 | Wiring method of superconducting quantum bit system for surface coding scheme and wiring board |
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