Spectral kissing and its dynamical consequences in the squeeze-driven Kerr oscillator
Spectral kissing and its dynamical consequences in the squeeze-driven Kerr oscillator
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DOI：
10.1038/s41534-023-00745-1
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发表时间：
2022-10
影响因子：
7.6
通讯作者：
J. Ch'avez-Carlos;Talía L. M. Lezama;R. Cortiñas;J. Venkatraman;M. Devoret;V. Batista;F. P'erez-Bernal;L. F. Santos
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作者：
J. Ch'avez-Carlos;Talía L. M. Lezama;R. Cortiñas;J. Venkatraman;M. Devoret;V. Batista;F. P'erez-Bernal;L. F. Santos
由于其可控性和易于工程实现，Transmon量子比特是基于电路的量子信息处理的主要元素，例如现有的量子计算机。但与量子比特不同的是，超子是可以用来研究基本物理问题的多级非线性振荡器。在这里，它们被作为激发态量子相变(ESQPTs)的模拟器来探索，ESQPTs是量子相变到激发态的推广。我们发现，在被驱动的蜗牛传输子的有效哈密顿量中实验观察到的光谱接吻(能级对的合并)是ESQPT的前驱。我们探讨了ESQPT的动力学后果，其中包括超时有序相关器的指数增长，随后是周期性的复苏，以及由于局部化而导致的生存概率的缓慢演化。ESQPT的这些特征对于目前的超导电路平台是可以到达的，并且对于冷原子和离子陷阱的实验是感兴趣的。
Transmon qubits are the predominant element in circuit-based quantum information processing, such as existing quantum computers, due to their controllability and ease of engineering implementation. But more than qubits, transmons are multilevel nonlinear oscillators that can be used to investigate fundamental physics questions. Here, they are explored as simulators of excited state quantum phase transitions (ESQPTs), which are generalizations of quantum phase transitions to excited states. We show that the spectral kissing (coalescence of pairs of energy levels) experimentally observed in the effective Hamiltonian of a driven SNAIL-transmon is an ESQPT precursor. We explore the dynamical consequences of the ESQPT, which include the exponential growth of out-of-time-ordered correlators, followed by periodic revivals, and the slow evolution of the survival probability due to localization. These signatures of ESQPT are within reach for current superconducting circuits platforms and are of interest to experiments with cold atoms and ion traps.