Strachan David J, Purkayastha Archak, Clark Stephen R
University of Bristol, H. H. Wills Physics Laboratory, Bristol BS8 1TL, United Kingdom.
Indian Institute of Technology, Department of Physics, Hyderabad 502284, India.
Phys Rev Lett. 2025 Jun 6;134(22):220403. doi: 10.1103/PhysRevLett.134.220403.
Since its rediscovery in the twentieth century, the Mpemba effect, where a far-from-equilibrium state may relax faster than a state closer to equilibrium, has been extensively studied in classical systems and has recently received attention in quantum systems. Many theories explaining this counter-intuitive behavior in classical systems rely on memory effects. However, in quantum systems, the relation between the Mpemba effect and memory has remained unexplored. In this Letter, we consider general non-Markovian open quantum systems and reveal new classes of quantum Mpemba effects, with no analog in Markovian quantum dynamics. Generically, open quantum dynamics possess a finite memory time and a unique steady state. Because of non-Markovian dynamics, even if the system is initialized in the steady state it can take a long time to relax back. We find other initial states that reach the steady state much faster. Most notably, we demonstrate that there can be an initial state in which the system reaches the steady state within the finite memory time itself, giving the fastest possible relaxation to stationarity. We verify the effect for quantum dot systems coupled to electronic reservoirs in equilibrium and nonequilibrium setups at weak, intermediate and strong coupling. Our Letter provides new insights into the rich physics underlying accelerated relaxation in quantum systems.
自20世纪被重新发现以来，姆潘巴效应（即远离平衡态的状态可能比更接近平衡态的状态弛豫得更快）已在经典系统中得到广泛研究，并且最近在量子系统中也受到了关注。许多解释经典系统中这种反直觉行为的理论都依赖于记忆效应。然而，在量子系统中，姆潘巴效应与记忆之间的关系仍未得到探索。在本论文中，我们考虑一般的非马尔可夫开放量子系统，并揭示了新型的量子姆潘巴效应，这在马尔可夫量子动力学中并无类似情况。一般而言，开放量子动力学具有有限的记忆时间和唯一的稳态。由于非马尔可夫动力学，即使系统在稳态下初始化，它也可能需要很长时间才能弛豫回来。我们发现了其他能更快达到稳态的初始状态。最值得注意的是，我们证明可能存在一种初始状态，在这种状态下系统能在有限的记忆时间内自身达到稳态，从而实现最快的向平稳态弛豫。我们在弱、中、强耦合的平衡和非平衡设置下，对耦合到电子库的量子点系统验证了这种效应。我们的论文为量子系统中加速弛豫背后丰富的物理现象提供了新的见解。
