Irreversibility and the Arrow of Time in a Quenched Quantum System

T. B. Batalhão, A. M. Souza, R. S. Sarthour, I. S. Oliveira, M. Paternostro, E. Lutz, R. M. Serra

Research output: Contribution to journalLetter

64 Citations (Scopus)
315 Downloads (Pure)

Abstract

Irreversibility is one of the most intriguing concepts in physics. While microscopic physical laws are perfectly reversible, macroscopic average behavior has a preferred direction of time. According to the second law of thermodynamics, this arrow of time is associated with a positive mean entropy production. Using a nuclear magnetic resonance setup, we measure the nonequilibrium entropy produced in an isolated spin-1/2 system following fast quenches of an external magnetic field and experimentally demonstrate that it is equal to the entropic distance, expressed by the Kullback-Leibler divergence, between a microscopic process and its time-reverse. Our result addresses the concept of irreversibility from a microscopic quantum standpoint.
Original languageEnglish
Article number190601
Number of pages5
JournalPhysical Review Letters
Volume115
Issue number19
DOIs
Publication statusPublished - 02 Nov 2015

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