WO2023142324A1 - Method for achieving double-bit quantum gate on basis of superconducting quantum coupler - Google Patents

Method for achieving double-bit quantum gate on basis of superconducting quantum coupler Download PDF

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WO2023142324A1
WO2023142324A1 PCT/CN2022/096264 CN2022096264W WO2023142324A1 WO 2023142324 A1 WO2023142324 A1 WO 2023142324A1 CN 2022096264 W CN2022096264 W CN 2022096264W WO 2023142324 A1 WO2023142324 A1 WO 2023142324A1
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quantum
double
bit
coupling unit
superconducting
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李少炜
叶杨森
龚明
吴玉林
梁福田
彭承志
朱晓波
潘建伟
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中国科学技术大学
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    • G06N10/00—Quantum computing, i.e. information processing based on quantum-mechanical phenomena

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  • the disclosure belongs to the technical field of quantum computing, and in particular relates to a method for realizing a double-bit quantum gate by using a microwave pulse and a superconducting quantum coupler.
  • the disclosure provides a method for realizing a double-bit quantum gate based on a superconducting quantum coupler, the superconducting quantum coupler includes two qubits and a quantum coupling unit between the two qubits, and the superconducting quantum
  • the methods for couplers to implement double-bit quantum gates include:
  • a double-bit quantum gate is realized by applying a current pulse to the quantum coupling unit.
  • increasing the forward coupling strength between the two qubits includes: increasing the capacitance of the direct coupling capacitor between the two qubits.
  • the quantum coupling unit includes a parallel capacitance branch and a superconducting quantum interferometer branch, increasing the maximum eigenfrequency of the quantum coupling unit, including: reducing the capacitance value of the capacitance branch of the quantum coupling unit; and reducing The inductance of the superconducting quantum interferometer branch of the quantum coupling unit.
  • the superconducting quantum interferometer branch includes an asymmetric double Josephson junction.
  • the frequency of the quantum coupling unit and the frequency of the qubit are always kept above the set detuning amount.
  • the critical current ratio of the two Josephson junctions in the asymmetric double Josephson junction is adjusted to be 1:2 ⁇ 1:2.5.
  • the equivalent coupling strength is the sum of the forward coupling strength and the negative coupling strength of the quantum coupling unit.
  • the set detuning amount is 1 GHz.
  • the disclosed method for realizing a double-bit quantum gate based on a superconducting quantum coupler can realize an AC CZ gate in a shorter time; the shorter quantum gate time can reduce the decoherence error of the qubit, and improve the performance of the AC CZ gate. Fidelity and experimental application value; it satisfies the need to quickly realize the CZ gate and reduce the CZ gate through microwave pulses, and reduce the control error caused by the residual voltage.
  • FIG. 1 is a flowchart of a method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to an embodiment of the present disclosure
  • FIG. 2 is a schematic diagram of a circuit principle of a double-bit quantum gate based on a superconducting quantum coupler according to an embodiment of the present disclosure
  • FIG. 3 is a schematic diagram of the change curve of the equivalent coupling strength between qubits and the magnetic flux ⁇ c of the quantum coupling unit according to an embodiment of the present disclosure.
  • the disclosure provides a method for realizing a double-bit quantum gate, which can increase the absolute value of the equivalent coupling strength to more than 10 MHz in both positive and negative directions.
  • a double-bit quantum gate which can increase the absolute value of the equivalent coupling strength to more than 10 MHz in both positive and negative directions.
  • the microwave pulse applied to the quantum coupler is used to realize the high-fidelity control phase gate with small microwave residual pulse and the possibility of frequency division multiplexing, which can be well applied to large-scale qubits in the future expansion. Certain changes are made on the basis of existing technical solutions to form a quantum computer with stronger performance.
  • Fig. 1 is a flowchart of a method for realizing a double-bit quantum gate based on a superconducting quantum coupler in an embodiment of the present disclosure
  • Fig. 2 is a schematic diagram of a circuit principle of a double-bit quantum gate based on a superconducting quantum coupler in an embodiment of the present disclosure
  • the superconducting quantum coupler includes two qubits (the first qubit 100 and the second qubit 200) and a quantum coupling between the two qubits.
  • Unit 300 as shown in FIG.
  • the first qubit 100 includes a first capacitor branch and a first quantum interferometer branch, wherein the capacitance of the first capacitor branch is C qubit1 , and the first quantum interferometer branch
  • the value of the inductance is L q1 , and the corresponding magnetic flux is ⁇ Q1
  • the second qubit 100 includes a second capacitor branch and a second quantum interferometer branch, wherein the capacitance of the second capacitor branch is C qubit2 ,
  • the inductance value of the second quantum interferometer branch is L q2 , and the corresponding magnetic flux is ⁇ Q2 ;
  • the difference between the qubit and the quantum coupling unit lies in the capacitance parameters C qubit1 and C qubit2 of the capacitance branch and the value of C cpuler
  • the value of , and the inductance parameter L q1 , L q2 and L c are different.
  • C qq is the direct coupling capacitance between two qubits
  • C qc1 is the coupling capacitance between the first qubit and the quantum coupling unit
  • C qc2 is the coupling capacitance between the second qubit and the quantum coupling unit.
  • the method for realizing a double-bit quantum gate based on a superconducting quantum coupler includes:
  • Operation S1 increasing the forward coupling strength between the two qubits
  • Operation S2 increasing the maximum eigenfrequency of the quantum coupling unit
  • Operation S3 adjusting the circuit parameters of the quantum coupling unit so that the frequency and the qubit frequency are always above the set detuning amount;
  • Operation S4 implementing a double-bit quantum gate by applying a current pulse to the quantum coupling unit.
  • the forward coupling strength between the first qubit 100 and the second qubit 200 is increased by increasing the direct coupling capacitance C qq between the two qubits.
  • the direct coupling The capacitance of the capacitor C qq is increased to 4fF or above.
  • the quantum coupling unit includes a parallel capacitor branch 310 and a superconducting quantum interferometer branch 320
  • the raising the maximum eigenfrequency of the quantum coupling unit includes: reducing the quantum coupling the capacitance value C coupler of the capacitor branch of the unit; and reduce the inductance L c of the superconducting quantum interference device branch of the quantum coupling unit.
  • the maximum eigenfrequency of the quantum coupling unit is increased to 10GHz or above.
  • the superconducting quantum interferometer branch 320 includes an asymmetric double Josephson junction, and by adjusting the critical current ratio of the asymmetric double Josephson junction in the superconducting quantum interferometer branch, the quantum coupling unit frequency and The qubit frequency is always kept above the set detuning amount; for example, the critical current ratio of two Josephson junctions in an asymmetric double Josephson junction is adjusted to be 1:2 to 1:2.5.
  • the direct coupling strength (or called forward coupling strength) between the qubits increases; at the same time, due to the increase of the maximum eigenfrequency of the quantum coupling unit, when the quantum coupling When the frequency of the unit is the maximum eigenfrequency, the qubit and the quantum coupling unit have a large frequency detuning, and the indirect coupling strength (or negative coupling strength) realized by the quantum coupling unit is small.
  • a double-bit quantum gate is realized by applying a current pulse to the superconducting quantum interferometer branch of the quantum coupling unit.
  • the rapid change of the equivalent coupling strength beyond the range of -10MHz to 10MHz can be realized, when the frequency of the change is equal to the frequency difference between two bits
  • the axis of ordinate represents the equivalent coupling strength (g/2 ⁇ )
  • the axis of abscissa represents the magnetic flux ⁇ c , the unit of which is the flux quantum ( ⁇ 0 ).
  • This change curve satisfies (1) the absolute value of the two-way equivalent coupling strength can reach more than 10MHz; (2) the equivalent coupling strength has a good linear relationship with ⁇ c near 0; (3) in the flux adjustment process
  • the frequency of the quantum coupler and the qubit frequency always maintain a detuning amount of more than 1 GHz, so the magnetic flux ⁇ c of the quantum coupler can be adjusted well.
  • the present disclosure provides a method for realizing a double-bit quantum gate based on a superconducting quantum coupler, which can quickly realize an AC CZ gate within 100 ns by adjusting the magnetic flux ⁇ c of the quantum coupler in an experiment. And in the range of qubit frequency difference 0-500MHz, more than half of the frequency range can realize high-fidelity CZ gate with simulation fidelity greater than 99.99%. It satisfies the requirement of quickly realizing the CZ gate and reducing the non-decoherence error of the AC CZ gate through the microwave pulse.

Abstract

The present invention provides a method for achieving a double-bit quantum gate on the basis of a superconducting quantum coupler. The superconducting quantum coupler comprises two quantum bits and a quantum coupling unit located between the two quantum bits. The method comprises: improving forward coupling strength between the two quantum bits; increasing the maximum eigenfrequency of the quantum coupling unit; adjusting circuit parameters of the quantum coupling unit such that the frequency of the quantum coupling unit and the frequencies of the quantum bits are always kept above a set detuning amount; and achieving a double-bit quantum gate by applying a current pulse to the quantum coupling unit.

Description

基于超导量子耦合器实现双比特量子门的方法A Method of Realizing Double Bit Quantum Gate Based on Superconducting Quantum Coupler 技术领域technical field
本公开属于量子计算技术领域，具体涉及一种利用微波脉冲和超导量子耦合器实现双比特量子门的方法。The disclosure belongs to the technical field of quantum computing, and in particular relates to a method for realizing a double-bit quantum gate by using a microwave pulse and a superconducting quantum coupler.
背景技术Background technique
当今是量子计算机技术发展的初级阶段，如何实现对量子系统的精密调控是量子计算发展的重点。由超导量子比特实现的超导量子芯片是当前量子计算最行之有效的物理平台之一，如何利用电学脉冲实现对超导量子芯片的高精度调控是提高量子操控精度的核心技术与挑战。为了避免单极性控制脉冲产生的残余电压对量子门的影响，需要发展利用微波脉冲实现双比特量子门的技术。但微波脉冲实现量子门的速度通常较慢，如何通过合适的超导量子耦合器配置，在保证量子比特单比特门性能的同时，快速实现两比特量子门，是亟待解决的技术课题之一。Today is the initial stage of the development of quantum computer technology. How to realize the precise control of quantum systems is the focus of the development of quantum computing. Superconducting quantum chips realized by superconducting qubits are currently one of the most effective physical platforms for quantum computing. How to use electrical pulses to achieve high-precision regulation of superconducting quantum chips is the core technology and challenge to improve the precision of quantum manipulation. In order to avoid the influence of the residual voltage generated by the unipolar control pulse on the quantum gate, it is necessary to develop the technology of using microwave pulses to realize the double-bit quantum gate. However, the speed of microwave pulses to realize quantum gates is usually slow. How to quickly realize two-bit quantum gates while ensuring the performance of qubit single-bit gates through a suitable superconducting quantum coupler configuration is one of the technical issues to be solved urgently.
发明内容Contents of the invention
本公开提供一种基于超导量子耦合器实现双比特量子门的方法，所述超导量子耦合器包括两个量子比特和位于两个量子比特之间的量子耦合单元，所述基于超导量子耦合器实现双比特量子门的方法包括：The disclosure provides a method for realizing a double-bit quantum gate based on a superconducting quantum coupler, the superconducting quantum coupler includes two qubits and a quantum coupling unit between the two qubits, and the superconducting quantum The methods for couplers to implement double-bit quantum gates include:
提高两个量子比特之间的正向耦合强度；Increase the forward coupling strength between two qubits;
提升量子耦合单元的最大本征频率；以及increasing the maximum eigenfrequency of the quantum coupling unit; and
对量子耦合单元电路参数进行调节使其频率与量子比特频率始终保持设定的失谐量之上；Adjust the circuit parameters of the quantum coupling unit so that the frequency and the qubit frequency are always above the set detuning amount;
通过在量子耦合单元施加电流脉冲，实现双比特量子门。A double-bit quantum gate is realized by applying a current pulse to the quantum coupling unit.
可选地，提高两个量子比特之间的正向耦合强度，包括：提升两个量子比特间的直接耦合电容的容值。Optionally, increasing the forward coupling strength between the two qubits includes: increasing the capacitance of the direct coupling capacitor between the two qubits.
可选地，提升两个量子比特间的直接耦合电容的容值至4fF以上。Optionally, increase the capacitance of the direct coupling capacitor between the two qubits to above 4fF.
可选地，量子耦合单元包括并联的电容支路和超导量子干涉器支路，提升量子耦合单元的最大本征频率，包括：减小量子耦合单元的电容支路的电容值；以及减小量子耦合单元的超导量子干涉器支路的电感量。Optionally, the quantum coupling unit includes a parallel capacitance branch and a superconducting quantum interferometer branch, increasing the maximum eigenfrequency of the quantum coupling unit, including: reducing the capacitance value of the capacitance branch of the quantum coupling unit; and reducing The inductance of the superconducting quantum interferometer branch of the quantum coupling unit.
可选地，超导量子干涉器支路包括非对称的双约瑟夫森结。Optionally, the superconducting quantum interferometer branch includes an asymmetric double Josephson junction.
可选地，通过调节超导量子干涉器支路中非对称的双约瑟夫森结的临界电流比使量子耦 合单元频率与量子比特频率始终保持设定的失谐量之上。Optionally, by adjusting the critical current ratio of the asymmetric double Josephson junction in the branch of the superconducting quantum interference device, the frequency of the quantum coupling unit and the frequency of the qubit are always kept above the set detuning amount.
可选地，调节非对称的双约瑟夫森结中两个约瑟夫森结的临界电流比为1∶2～1∶2.5。Optionally, the critical current ratio of the two Josephson junctions in the asymmetric double Josephson junction is adjusted to be 1:2˜1:2.5.
可选地，调节量子耦合单元的耦合器的磁通，实现等效耦合强度超过-10MHz到10MHz范围的快速变化，当变化的频率等于双量子比特|11＞态和|20＞态的频率差时，实现双比特量子门。Optionally, adjust the magnetic flux of the coupler of the quantum coupling unit to realize the rapid change of the equivalent coupling strength beyond the range of -10MHz to 10MHz, when the frequency of the change is equal to the frequency difference between the two-qubit |11>state and |20>state , realize the double-bit quantum gate.
可选地，等效耦合强度为量子耦合单元的正向耦合强度与负向耦合强度的和。Optionally, the equivalent coupling strength is the sum of the forward coupling strength and the negative coupling strength of the quantum coupling unit.
可选地，设定的失谐量为1GHz。Optionally, the set detuning amount is 1 GHz.
本公开的基于超导量子耦合器实现双比特量子门的方法，能够在更短的时间内实现交流CZ门；较短的量子门时间可以减小量子比特的退相干错误，提高了交流CZ门的保真度和实验应用价值；很好的满足了通过微波脉冲快速实现CZ门并减小CZ门，减小残余电压引起的控制误差。The disclosed method for realizing a double-bit quantum gate based on a superconducting quantum coupler can realize an AC CZ gate in a shorter time; the shorter quantum gate time can reduce the decoherence error of the qubit, and improve the performance of the AC CZ gate. Fidelity and experimental application value; it satisfies the need to quickly realize the CZ gate and reduce the CZ gate through microwave pulses, and reduce the control error caused by the residual voltage.
附图说明Description of drawings
图1为本公开实施例的基于超导量子耦合器实现双比特量子门的方法的流程图；FIG. 1 is a flowchart of a method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to an embodiment of the present disclosure;
图2为本公开实施例的基于超导量子耦合器实现双比特量子门的电路原理示意图；2 is a schematic diagram of a circuit principle of a double-bit quantum gate based on a superconducting quantum coupler according to an embodiment of the present disclosure;
图3为本公开实施例的量子比特之间的等效耦合强度与量子耦合单元的磁通Φ c的变化曲线示意图。 FIG. 3 is a schematic diagram of the change curve of the equivalent coupling strength between qubits and the magnetic flux Φ c of the quantum coupling unit according to an embodiment of the present disclosure.
附图标记：Reference signs:
100第一量子比特；200第二量子比特；300量子耦合单元；310电容支路；100 first qubits; 200 second qubits; 300 quantum coupling units; 310 capacitor branches;
320超导量子干涉器支路。320 superconducting quantum interferometer branches.
具体实施方式Detailed ways
本公开提供了一种实现双比特量子门的方法，可以在正负两个方向将等效耦合强度绝对值增加到10MHz以上。基于这一量子耦合器设计，通过变化耦合器的磁通，可以实现等效耦合强度超过-10MHz到10MHz范围的快速变化，当变化的频率等于两比特|11＞态和|20＞态的频率差时，就可以用于实现两比特CZ(Controlled-Z)门。由于我们的量子耦合器设计等效耦合强度可调节范围较大，基于这一耦合器实现的交流CZ门可以在更短的时间内实现。较短的量子门时间可以减小了量子比特的退相干错误，提高了交流CZ门的保真度和实验应用价值。The disclosure provides a method for realizing a double-bit quantum gate, which can increase the absolute value of the equivalent coupling strength to more than 10 MHz in both positive and negative directions. Based on this quantum coupler design, by changing the magnetic flux of the coupler, the rapid change of the equivalent coupling strength over the range of -10MHz to 10MHz can be realized, when the frequency of the change is equal to the frequency of two bits |11> state and |20> state When there is a difference, it can be used to realize a two-bit CZ (Controlled-Z) gate. Due to the large adjustable range of the equivalent coupling strength of our quantum coupler design, the AC CZ gate based on this coupler can be realized in a shorter time. The shorter quantum gate time can reduce the decoherence error of the qubit, and improve the fidelity and experimental application value of the AC CZ gate.
在超导量子芯片中，利用施加在量子耦合器上的微波脉冲，实现微波残余脉冲小，存在频分复用可能性的高保真度控制相位门，能够很好的适用于未来大规模量子比特的拓展。在 现有的技术方案基础上做出一定的改动从而形成了性能更强的量子计算机。In the superconducting quantum chip, the microwave pulse applied to the quantum coupler is used to realize the high-fidelity control phase gate with small microwave residual pulse and the possibility of frequency division multiplexing, which can be well applied to large-scale qubits in the future expansion. Certain changes are made on the basis of existing technical solutions to form a quantum computer with stronger performance.
下面结合附图对本公开的实施方式作进一步说明。Embodiments of the present disclosure will be further described below in conjunction with the accompanying drawings.
图1为本公开实施例的基于超导量子耦合器实现双比特量子门的方法的流程图；图2为本公开实施例的基于超导量子耦合器实现双比特量子门的电路原理示意图；本公开实施例中，结合图1和图2所示，所述超导量子耦合器包括两个量子比特(第一量子比特100和第二量子比特200)和位于两个量子比特之间的量子耦合单元300；如图2所示，第一量子比特100包括第一电容支路和第一量子干涉器支路，其中，第一电容支路的容值为C qubit1，第一量子干涉器支路的电感量值为L q1，对应的磁通为Φ Q1；第二量子比特100包括第二电容支路和第二量子干涉器支路，其中，第二电容支路的容值为C qubit2，第二量子干涉器支路的电感量值为L q2，对应的磁通为Φ Q2；量子比特和量子耦合单元的不同点在于电容支路的容值参数C qubit1、C qubit2的值和C cpupler的值，以及电感量参数L q1、L q2和L c的不同。C qq是两个量子比特间的直接耦合电容，C qc1是第一量子比特和量子耦合单元之间的耦合电容，C qc2是第二量子比特和量子耦合单元之间的耦合电容。 Fig. 1 is a flowchart of a method for realizing a double-bit quantum gate based on a superconducting quantum coupler in an embodiment of the present disclosure; Fig. 2 is a schematic diagram of a circuit principle of a double-bit quantum gate based on a superconducting quantum coupler in an embodiment of the present disclosure; In the disclosed embodiment, as shown in FIG. 1 and FIG. 2, the superconducting quantum coupler includes two qubits (the first qubit 100 and the second qubit 200) and a quantum coupling between the two qubits. Unit 300; as shown in FIG. 2 , the first qubit 100 includes a first capacitor branch and a first quantum interferometer branch, wherein the capacitance of the first capacitor branch is C qubit1 , and the first quantum interferometer branch The value of the inductance is L q1 , and the corresponding magnetic flux is Φ Q1 ; the second qubit 100 includes a second capacitor branch and a second quantum interferometer branch, wherein the capacitance of the second capacitor branch is C qubit2 , The inductance value of the second quantum interferometer branch is L q2 , and the corresponding magnetic flux is Φ Q2 ; the difference between the qubit and the quantum coupling unit lies in the capacitance parameters C qubit1 and C qubit2 of the capacitance branch and the value of C cpuler The value of , and the inductance parameter L q1 , L q2 and L c are different. C qq is the direct coupling capacitance between two qubits, C qc1 is the coupling capacitance between the first qubit and the quantum coupling unit, and C qc2 is the coupling capacitance between the second qubit and the quantum coupling unit.
所述基于超导量子耦合器实现双比特量子门的方法，包括：The method for realizing a double-bit quantum gate based on a superconducting quantum coupler includes:
操作S1：提高所述两个量子比特之间的正向耦合强度；Operation S1: increasing the forward coupling strength between the two qubits;
操作S2：提升所述量子耦合单元的最大本征频率；以及Operation S2: increasing the maximum eigenfrequency of the quantum coupling unit; and
操作S3：对量子耦合单元电路参数进行调节使其频率与量子比特频率始终保持设定的失谐量之上；Operation S3: adjusting the circuit parameters of the quantum coupling unit so that the frequency and the qubit frequency are always above the set detuning amount;
操作S4：通过在量子耦合单元施加电流脉冲，实现双比特量子门。Operation S4: implementing a double-bit quantum gate by applying a current pulse to the quantum coupling unit.
根据本公开实施例，通过提升两个量子比特间的直接耦合电容C qq来提升第一量子比特100和第二量子比特200之间的正向耦合强度，在本公开实施例中，将直接耦合电容C qq的容值提升至4fF或以上。 According to the embodiment of the disclosure, the forward coupling strength between the first qubit 100 and the second qubit 200 is increased by increasing the direct coupling capacitance C qq between the two qubits. In the embodiment of the disclosure, the direct coupling The capacitance of the capacitor C qq is increased to 4fF or above.
根据本公开实施例，所述量子耦合单元包括并联的电容支路310和超导量子干涉器支路320，所述提升所述量子耦合单元的最大本征频率，包括：减小所述量子耦合单元的电容支路的电容值C coupler；以及减小所述量子耦合单元的超导量子干涉器支路的电感量L c。使得量子耦合单元的最大本征频率提升到10GHz或以上。 According to an embodiment of the present disclosure, the quantum coupling unit includes a parallel capacitor branch 310 and a superconducting quantum interferometer branch 320, and the raising the maximum eigenfrequency of the quantum coupling unit includes: reducing the quantum coupling the capacitance value C coupler of the capacitor branch of the unit; and reduce the inductance L c of the superconducting quantum interference device branch of the quantum coupling unit. The maximum eigenfrequency of the quantum coupling unit is increased to 10GHz or above.
根据本公开实施例，超导量子干涉器支路320包括非对称的双约瑟夫森结，通过调节超 导量子干涉器支路中非对称的双约瑟夫森结的临界电流比使量子耦合单元频率与量子比特频率始终保持设定的失谐量之上；例如调节非对称的双约瑟夫森结中两个约瑟夫森结的临界电流比为1∶2～1∶2.5。According to an embodiment of the present disclosure, the superconducting quantum interferometer branch 320 includes an asymmetric double Josephson junction, and by adjusting the critical current ratio of the asymmetric double Josephson junction in the superconducting quantum interferometer branch, the quantum coupling unit frequency and The qubit frequency is always kept above the set detuning amount; for example, the critical current ratio of two Josephson junctions in an asymmetric double Josephson junction is adjusted to be 1:2 to 1:2.5.
通过以上操作，由于直接耦合电容C qq的提高，使得量子比特之间的直接耦合强度(或称为正向耦合强度)增大；同时由于量子耦合单元的最大本征频率的提高，当量子耦合单元的频率取最大本征频率时，量子比特和量子耦合单元有较大频率失谐，通过量子耦合单元实现的间接耦合强度(或称为负向耦合强度)较小。在两方面的作用下，可以在量子耦合单元的磁通Φ c＝0时，实现10MHz以上的正向等效耦合强度(等效耦合强度＝直接耦合强度+间接耦合强度)。 Through the above operations, due to the increase of the direct coupling capacitance C qq , the direct coupling strength (or called forward coupling strength) between the qubits increases; at the same time, due to the increase of the maximum eigenfrequency of the quantum coupling unit, when the quantum coupling When the frequency of the unit is the maximum eigenfrequency, the qubit and the quantum coupling unit have a large frequency detuning, and the indirect coupling strength (or negative coupling strength) realized by the quantum coupling unit is small. Under the influence of two aspects, when the magnetic flux Φ c of the quantum coupling unit is 0, a forward equivalent coupling strength above 10 MHz can be realized (equivalent coupling strength=direct coupling strength+indirect coupling strength).
在实现较大(＞10MHz)的正向等效耦合强度时，为了实现(1)负向耦合也能实现较大的耦合强度；(2)等效耦合强度在0附近与Φ c有较好的线性关系；(3)在磁通调节过程中量子耦合单元的频率与量子比特频率始终保持1GHz以上的失谐量；需要将量子耦合单元的超导量子干涉器(SQUID)中的两个非对称约瑟夫森结的临界电流参数调节成1∶2～1∶2.5。 When achieving a larger (>10MHz) positive equivalent coupling strength, in order to achieve (1) negative coupling can also achieve a larger coupling strength; (2) the equivalent coupling strength has a better relationship with Φ c near 0 (3) In the flux adjustment process, the frequency of the quantum coupling unit and the qubit frequency always maintain a mismatch of more than 1 GHz; it is necessary to combine the two non- The critical current parameter of the symmetrical Josephson junction is adjusted to 1:2～1:2.5.
根据本公开实施例，通过在量子耦合单元的超导量子干涉器支路施加电流脉冲，实现双比特量子门。According to an embodiment of the present disclosure, a double-bit quantum gate is realized by applying a current pulse to the superconducting quantum interferometer branch of the quantum coupling unit.
根据本公开实施例，通过变化耦合器的磁通，可以实现等效耦合强度超过-10MHz到10MHz范围的快速变化，当变化的频率等于两比特|11＞态和|20＞态的频率差时，就可以用于实现两比特CZ门。According to the embodiment of the present disclosure, by changing the magnetic flux of the coupler, the rapid change of the equivalent coupling strength beyond the range of -10MHz to 10MHz can be realized, when the frequency of the change is equal to the frequency difference between two bits |11> state and |20> state , can be used to realize the two-bit CZ gate.
根据本公开实施例，如图3所示，纵坐标轴表示等效耦合强度(g/2π)，横坐标轴表示磁通量φ c，其单位为磁通量子(φ 0)，综合以上几点的操作及设置，可以实现图3中的等效耦合强度变化曲线。这一变化曲线由于满足(1)双向等效耦合强度绝对值都能达到10MHz以上；(2)等效耦合强度在0附近与Φ c有较好的线性关系；(3)在磁通调节过程中量子耦合器的频率与量子比特频率始终保持1GHz以上的失谐量，因此可以很好的通过调节量子耦合器磁通Φ c，当变化的频率等于两比特|11＞态和|20＞态的频率差时，在100ns的时间内，快速的实现交流CZ门。并且在量子比特频率差为0-500MHz区间内，一半以上的频率区间都可以实现仿真保真度大于99.99％的高保真度CZ门。 According to the embodiment of the present disclosure, as shown in Figure 3, the axis of ordinate represents the equivalent coupling strength (g/2π), and the axis of abscissa represents the magnetic flux φ c , the unit of which is the flux quantum (φ 0 ). And setting, can realize the change curve of equivalent coupling strength in Fig. 3. This change curve satisfies (1) the absolute value of the two-way equivalent coupling strength can reach more than 10MHz; (2) the equivalent coupling strength has a good linear relationship with Φ c near 0; (3) in the flux adjustment process The frequency of the quantum coupler and the qubit frequency always maintain a detuning amount of more than 1 GHz, so the magnetic flux Φ c of the quantum coupler can be adjusted well. When the frequency of change is equal to two bits |11> state and |20> state When the frequency difference is high, the AC CZ gate can be quickly realized within 100ns. And in the range of qubit frequency difference 0-500MHz, more than half of the frequency range can realize high-fidelity CZ gate with simulation fidelity greater than 99.99%.
本公开提供了一种基于超导量子耦合器实现双比特量子门的方法，可以很好的在实验中通过调节量子耦合器磁通Φ c，在100n s的时间内快速的实现交流CZ门。并且在量子比特频率差为0-500MHz区间内，一半以上的频率区间都可以实现仿真保真度大于99.99％的高保真度CZ门。很好的满足了通过微波脉冲快速实现CZ门并减小交流CZ门非退相干误差的需求。 The present disclosure provides a method for realizing a double-bit quantum gate based on a superconducting quantum coupler, which can quickly realize an AC CZ gate within 100 ns by adjusting the magnetic flux Φ c of the quantum coupler in an experiment. And in the range of qubit frequency difference 0-500MHz, more than half of the frequency range can realize high-fidelity CZ gate with simulation fidelity greater than 99.99%. It satisfies the requirement of quickly realizing the CZ gate and reducing the non-decoherence error of the AC CZ gate through the microwave pulse.
以上所述本公开的具体实施方式，并不构成对本公开保护范围的限定。任何根据本公开的技术构思所作出的各种其他相应的改变与变形，均应包含在本公开权利要求的保护范围内。The specific implementation manners of the present disclosure described above are not intended to limit the protection scope of the present disclosure. Any other corresponding changes and modifications made according to the technical concepts of the present disclosure shall be included in the protection scope of the claims of the present disclosure.

Claims (10)

  1. 一种基于超导量子耦合器实现双比特量子门的方法，所述超导量子耦合器包括两个量子比特和位于两个量子比特之间的量子耦合单元，所述方法包括：A method for realizing a double-bit quantum gate based on a superconducting quantum coupler, the superconducting quantum coupler comprising two qubits and a quantum coupling unit between the two qubits, the method comprising:
    提高所述两个量子比特之间的正向耦合强度；increasing the forward coupling strength between the two qubits;
    提升所述量子耦合单元的最大本征频率；Promoting the maximum eigenfrequency of the quantum coupling unit;
    对量子耦合单元电路参数进行调节使其频率与量子比特频率始终保持设定的失谐量之上；以及Adjusting the circuit parameters of the quantum coupling unit so that the frequency and the qubit frequency are always above the set detuning amount; and
    通过在量子耦合单元施加电流脉冲，实现双比特量子门。A double-bit quantum gate is realized by applying a current pulse to the quantum coupling unit.
  2. 根据权利要求1所述的基于超导量子耦合器实现双比特量子门的方法，所述提高所述两个量子比特之间的正向耦合强度，包括：The method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 1, said improving the forward coupling strength between said two qubits, comprising:
    提升所述两个量子比特间的直接耦合电容的容值。increasing the capacitance of the direct coupling capacitor between the two qubits.
  3. 根据权利要求2所述的基于超导量子耦合器实现双比特量子门的方法，提升所述两个量子比特间的直接耦合电容的容值至4fF以上。According to the method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 2, the capacitance of the direct coupling capacitance between the two qubits is increased to above 4fF.
  4. 根据权利要求1所述的基于超导量子耦合器实现双比特量子门的方法，所述量子耦合单元包括并联的电容支路和超导量子干涉器支路，所述提升所述量子耦合单元的最大本征频率，包括：The method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 1, said quantum coupling unit comprising a parallel capacitor branch and a superconducting quantum interferometer branch, said boosting said quantum coupling unit Maximum eigenfrequency, including:
    减小所述量子耦合单元的电容支路的电容值；以及reducing the capacitance of the capacitive branch of the quantum coupling unit; and
    减小所述量子耦合单元的超导量子干涉器支路的电感量。The inductance of the superconducting quantum interferometer branch of the quantum coupling unit is reduced.
  5. 根据权利要求4所述的基于超导量子耦合器实现双比特量子门的方法，所述超导量子干涉器支路包括非对称的双约瑟夫森结。According to the method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 4, the superconducting quantum interferometer branch includes an asymmetric double Josephson junction.
  6. 根据权利要求5所述的基于超导量子耦合器实现双比特量子门的方法，通过调节超导量子干涉器支路中非对称的双约瑟夫森结的临界电流比使量子耦合单元频率与量子比特频率始终保持设定的失谐量之上。The method for realizing double-bit quantum gates based on superconducting quantum couplers according to claim 5, by adjusting the critical current ratio of the asymmetric double Josephson junction in the branch of the superconducting quantum interferometer to make the quantum coupling unit frequency and qubit The frequency always remains above the set detuning amount.
  7. 根据权利要求6所述的基于超导量子耦合器实现双比特量子门的方法，调节非对称的 双约瑟夫森结中两个约瑟夫森结的临界电流比为1∶2～1∶2.5。According to the method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 6, the critical current ratio of the two Josephson junctions in the asymmetric double Josephson junction is adjusted to be 1:2 to 1:2.5.
  8. 根据权利要求1所述的基于超导量子耦合器实现双比特量子门的方法，调节量子耦合单元的耦合器的磁通，实现等效耦合强度超过-10MHz到10MHz范围的快速变化，当变化的频率等于双量子比特|11＞态和|20＞态的频率差时，实现双比特量子门。According to the method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 1, the magnetic flux of the coupler of the quantum coupling unit is adjusted to realize the rapid change of the equivalent coupling strength exceeding the range of -10MHz to 10MHz, when the changed When the frequency is equal to the frequency difference between the two-qubit |11> state and the |20> state, the double-bit quantum gate is realized.
  9. 根据权利要求8所述的基于超导量子耦合器实现双比特量子门的方法，所述等效耦合强度为量子耦合单元的正向耦合强度与负向耦合强度的和。According to the method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 8, the equivalent coupling strength is the sum of the forward coupling strength and the negative coupling strength of the quantum coupling unit.
  10. 根据权利要求1所述的基于超导量子耦合器实现双比特量子门的方法，设定的失谐量为1GHz。According to the method for realizing a double-bit quantum gate based on a superconducting quantum coupler according to claim 1, the set detuning amount is 1 GHz.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100148853A1 (en) * 2005-04-26 2010-06-17 Harris Richard G Systems, devices, and methods for controllably coupling qubits
CN111598248A (en) * 2020-05-18 2020-08-28 南京希凌陆信息科技有限公司 Superconducting quantum chip and method for realizing control phase gate
CN111931941A (en) * 2020-07-15 2020-11-13 北京百度网讯科技有限公司 High-fidelity superconducting circuit structure, superconducting quantum chip and superconducting quantum computer
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

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100148853A1 (en) * 2005-04-26 2010-06-17 Harris Richard G Systems, devices, and methods for controllably coupling qubits
CN111598248A (en) * 2020-05-18 2020-08-28 南京希凌陆信息科技有限公司 Superconducting quantum chip and method for realizing control phase gate
CN111931941A (en) * 2020-07-15 2020-11-13 北京百度网讯科技有限公司 High-fidelity superconducting circuit structure, superconducting quantum chip and superconducting quantum computer
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

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