Dai X, Trappen R, Chen H, Melanson D, Yurtalan M A, Tennant D M, Martinez A J, Tang Y, Mozgunov E, Gibson J, Grover J A, Disseler S M, Basham J I, Novikov S, Das R, Melville A J, Niedzielski B M, Hirjibehedin C F, Serniak K, Weber S J, Yoder J L, Oliver W D, Zick K M, Lidar D A, Lupascu A
Institute for Quantum Computing, University of Waterloo, Waterloo, ON, Canada.
Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada.
Nat Commun. 2025 Jan 2;16(1):329. doi: 10.1038/s41467-024-55588-x.
Landau-Zener tunneling, which describes the transition in a two-level system during a sweep through an anti-crossing, is a model applicable to a wide range of physical phenomena. Realistic quantum systems are affected by dissipation due to coupling to their environments. An important aspect of understanding such open quantum systems is the relative energy scales of the system itself and the system-environment coupling, which distinguishes the weak- and strong-coupling regimes. Using a tunable superconducting flux qubit, we observe the crossover from weak to strong coupling to the environment in Landau-Zener tunneling. Our results confirm previous theoretical studies of dissipative Landau-Zener tunneling in the weak and strong coupling limits. We devise a spin bath model that effectively captures the crossover regime. This work is relevant for understanding the role of dissipation in quantum annealing, where the system is expected to go through a cascade of Landau-Zener transitions before reaching the target state.
朗道 - 齐纳隧穿描述了一个两能级系统在扫过一个反交叉点时的跃迁，它是一个适用于广泛物理现象的模型。实际的量子系统由于与环境耦合而受到耗散的影响。理解此类开放量子系统的一个重要方面是系统本身与系统 - 环境耦合的相对能量尺度，这区分了弱耦合和强耦合 regime。使用一个可调谐的超导磁通量子比特，我们观察到在朗道 - 齐纳隧穿中从与环境的弱耦合到强耦合的转变。我们的结果证实了先前关于弱耦合和强耦合极限下耗散朗道 - 齐纳隧穿的理论研究。我们设计了一个自旋浴模型，它有效地捕捉了转变 regime。这项工作对于理解耗散在量子退火中的作用具有重要意义，在量子退火中，系统预计在达到目标状态之前会经历一系列朗道 - 齐纳跃迁。
