Berke Christoph, Varvelis Evangelos, Trebst Simon, Altland Alexander, DiVincenzo David P
Institute for Theoretical Physics, University of Cologne, 50937, Cologne, Germany.
Institute for Quantum Information, RWTH Aachen University, 52056, Aachen, Germany.
Nat Commun. 2022 May 6;13(1):2495. doi: 10.1038/s41467-022-29940-y.
From the perspective of many-body physics, the transmon qubit architectures currently developed for quantum computing are systems of coupled nonlinear quantum resonators. A certain amount of intentional frequency detuning ('disorder') is crucially required to protect individual qubit states against the destabilizing effects of nonlinear resonator coupling. Here we investigate the stability of this variant of a many-body localized phase for system parameters relevant to current quantum processors developed by the IBM, Delft, and Google consortia, considering the cases of natural or engineered disorder. Applying three independent diagnostics of localization theory - a Kullback-Leibler analysis of spectral statistics, statistics of many-body wave functions (inverse participation ratios), and a Walsh transform of the many-body spectrum - we find that some of these computing platforms are dangerously close to a phase of uncontrollable chaotic fluctuations.
从多体物理学的角度来看，目前为量子计算开发的跨导量子比特架构是耦合非线性量子谐振器系统。为了保护单个量子比特状态免受非线性谐振器耦合的不稳定影响，至关重要的是需要一定量的有意频率失谐（“无序”）。在这里，我们考虑自然或人为无序的情况，研究与IBM、代尔夫特和谷歌联盟目前开发的量子处理器相关的系统参数下这种多体局域相变体的稳定性。应用局域化理论的三种独立诊断方法——光谱统计的库尔贝克-莱布勒分析、多体波函数统计（逆参与率）以及多体光谱的沃尔什变换——我们发现其中一些计算平台危险地接近不可控混沌波动阶段。
