Observing pure effects of counter-rotating terms without ultrastrong coupling: A single photon can simultaneously excite two qubits
Observing pure effects of counter-rotating terms without ultrastrong coupling: A single photon can simultaneously excite two qubits
复制标题
在没有超强耦合的情况下观察反向旋转项的纯效应：单个光子可以同时激发两个量子位
DOI：
10.1103/physreva.96.063820
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发表时间：
2017
影响因子：
2.9
通讯作者：
Nori Franco
中科院分区：
文献类型：
--
作者：
Wang Xin;Miranowicz Adam;Li Hong-Rong;Nori Franco
Garzianoet等人最近在理论上预言了一个光子同时激发两个量子比特的相干过程。[L. Garziano，V. Macrande，R.斯塔西岛Di Stefano，F. Nori和S. Savasta，一个光子可以同时激发两个或多个原子，物理学评论。117，043601（2016）PRLTAO0031-900710.1103/PhysRevLett.117.043601]。我们提出了一种不同的方法来观察一个类似的动力学过程的基础上超导量子电路，其中两个耦合通量量子比特纵向相互作用的同一个谐振器。我们证明了两个量子比特的同时激发（假设它们的跃迁频率之和接近腔频率）与两个量子比特之间偶极-偶极耦合中的反向旋转项有关，并且标准的行波近似在这里是无效的。通过数值模拟绝热Landau-Zener跃迁和Rabi振荡效应，我们清楚地验证了单光子能量可以通过纵向耦合和反转项引起的高阶跃迁激发两个量子比特.与以前的研究相比，我们的系统中的相干动力学只涉及一个中间态，因此，表现出更快的速率。我们还发现了可能干扰的过渡路径。最后，通过讨论如何控制这两种相干耦合强度，我们找到了在我们的系统中同时观察相长干涉和相消干涉现象的方法。
The coherent process that a single photon simultaneously excites two qubits has recently been theoretically predicted by Garzianoet al.[L. Garziano, V. Macrì, R. Stassi, O. Di Stefano, F. Nori, and S. Savasta, One Photon Can Simultaneously Excite two or More Atoms, Phys. Rev. Lett. 117, 043601 (2016)PRLTAO0031-900710.1103/PhysRevLett.117.043601]. We propose a different approach to observe a similar dynamical process based on a superconducting quantum circuit, where two coupled flux qubits longitudinally interact with the same resonator. We show that this simultaneous excitation of two qubits (assuming that the sum of their transition frequencies is close to the cavity frequency) is related to the counter-rotating terms in the dipole-dipole coupling between two qubits, and the standard rotating-wave approximation is not valid here. By numerically simulating the adiabatic Landau-Zener transition and Rabi-oscillation effects, we clearly verify that the energy of a single photon can excite two qubits via higher-order transitions induced by the longitudinal couplings and the counter-rotating terms. Compared with previous studies, the coherent dynamics in our system only involves one intermediate state and, thus, exhibits a much faster rate. We also find transition paths which can interfere. Finally, by discussing how to control the two longitudinal-coupling strengths, we find a method to observe both constructive and destructive interference phenomena in our system.