Jayaseelan Maitreyi, K Manikandan Sreenath, Jordan Andrew N, Bigelow Nicholas P
Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA.
Center for Coherence and Quantum Optics, University of Rochester, Rochester, NY, USA.
Nat Commun. 2021 Mar 23;12(1):1847. doi: 10.1038/s41467-021-22094-3.
The origin of macroscopic irreversibility from microscopically time-reversible dynamical laws-often called the arrow-of-time problem-is of fundamental interest in both science and philosophy. Experimentally probing such questions in quantum theory requires systems with near-perfect isolation from the environment and long coherence times. Ultracold atoms are uniquely suited to this task. We experimentally demonstrate a striking parallel between the statistical irreversibility of wavefunction collapse and the arrow of time problem in the weak measurement of the quantum spin of an atomic cloud. Our experiments include statistically rare events where the arrow of time is inferred backward; nevertheless we provide evidence for absolute irreversibility and a strictly positive average arrow of time for the measurement process, captured by a fluctuation theorem. We further demonstrate absolute irreversibility for measurements performed on a quantum many-body entangled wavefunction-a unique opportunity afforded by our platform-with implications for studying quantum many-body dynamics and quantum thermodynamics.
源于微观时间可逆动力学定律的宏观不可逆性——通常被称为时间箭头问题——在科学和哲学领域都具有根本重要性。在量子理论中通过实验探究此类问题需要系统与环境近乎完美隔离且具有长相干时间。超冷原子特别适合这项任务。我们通过实验证明了波函数坍缩的统计不可逆性与原子云量子自旋弱测量中的时间箭头问题之间存在显著的相似性。我们的实验包括统计上罕见的时间箭头被反向推断的事件；然而，我们为测量过程的绝对不可逆性和严格正的平均时间箭头提供了证据，这由一个涨落定理所捕获。我们还证明了对量子多体纠缠波函数进行测量时的绝对不可逆性——这是我们的平台所提供的独特机会——对研究量子多体动力学和量子热力学具有重要意义。
