| 超强耦合电路量子电动力学系统中反旋波效应对量子比特频率移动的影响 |
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| 引用本文： | 陈臻,王帅鹏,李铁夫,游建强. 超强耦合电路量子电动力学系统中反旋波效应对量子比特频率移动的影响[J]. 物理学报, 2020, 0(12): 61-67 |
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| 作者姓名： | 陈臻 王帅鹏 李铁夫 游建强 |
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| 作者单位： | 北京计算科学研究中心量子物理与量子信息研究部;浙江大学物理系;清华大学微电子学研究所;北京量子信息科学研究院 |
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| 基金项目： | 国家重点研发计划(批准号:2016YFA0301200);科学挑战计划(批准号:TZ2018003);国家自然科学基金(批准号:U1930402);BAQIS研究计划(批准号:Y18G27)资助的课题。 |
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| 摘 要： | 从实验上研究了四结磁通量子比特与多模共面波导谐振腔构成的超强耦合电路量子电动力学系统.通过传输谱测量和数值拟合,确定量子比特与腔第一模式的耦合强度已达到0.1倍谐振腔频率,进入了超强耦合区域;通过色散读出方法得到了系统的能谱,并通过增加探测场光子,从能谱上得到了量子比特频率随探测光子的位移.这种位移不仅包含旋波项的贡献,也包含了反旋波项的显著贡献,证实我们所实现的超强耦合系统是一个良好的研究量子拉比模型的实验平台,它在量子技术的诸多方面有潜在的应用,如量子模拟、超快量子逻辑门、纠缠态制备、量子比特保护等.
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| 关 键 词： | 磁通量子比特 超强耦合 量子拉比模型 布洛赫-西格特位移 |
Counter-rotating effect on frequency shift of flux qubit in ultrastrongly coupled circuit-quantumelectrodynamics system |
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| Chen Zhen,Wang Shuai-Peng,Li Tie-Fu,You Jian-Qiang. Counter-rotating effect on frequency shift of flux qubit in ultrastrongly coupled circuit-quantumelectrodynamics system[J]. Acta Physica Sinica, 2020, 0(12): 61-67 |
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| Authors: | Chen Zhen Wang Shuai-Peng Li Tie-Fu You Jian-Qiang |
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| Affiliation: | (Quantum Physics and Quantum Information Division,Beijing Computational Science Research Center,Beijing 100193,China;Department of Physics,Zhejiang University,Hangzhou 310027,China;Center for Quantum Information Frontier Science,Institute of Microelectronics,Tsinghua University,Beijing 100084,China;Beijing Academy of Quantum Information,Beijing 100193,China) |
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| Abstract: | In recent years,quantum Rabi model has aroused considerable interest because of its fundamental importance and potential applications in quantum technologies.For a conventional cavity-quantumelectrodynamic(cavity-QED)system involving the interaction between an atom and photons in a cavity,the atom-photon coupling frequency is much smaller than the transition frequency of the atom and the frequency of the cavity mode.This cavity-QED system is usually described by the Jaynes-Cummings model in which the rotating-wave approximation can be adopted by neglecting the counter-rotating coupling terms in the Hamiltonian of the system.However,by designing the unique structure of the superconducting circuit,the ultrastrong-coupling regime can be achieved in a circuit-QED system in which the counter-rotating coupling terms become as important as the rotating terms.Thus,the rotating-wave approximation cannot be used in the ultrastrongly coupled circuit-QED system.Owing to the ultrastrong coupling,this circuit-QED system is described by the standard quantum Rabi model when a superconducting qubit is coupled only to a single resonator mode.In this work,we experimentally study an ultrastrongly coupled circuit-QED system consisting of a four-junction superconducting flux qubit and a muti-mode coplanar-waveguide resonator.The transmissionspectrum measurement and numerical simulations show that the system is in the ultrastrong-coupling regime.By changing the photon number in the resonator,we observe the frequency shift of the flux qubit via the spectroscopic measurement.This frequency shift contains the contributions from not only the rotating-coupling terms but also the counter-rotating terms,which is in good agreement with the theory.The result indicates that this ultrastrongly-coupled quantum system can be used as a good platform to investigate the quantum Rabi model and has potential applications in various aspects of quantum technology,such as quantum simulation,ultrafast quantum gates,entangled-state preparation and protected qubits. |
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| Keywords: | superconducting flux qubit ultrastrong coupling quantum Rabi model Bloch-Siegert shift |
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