Quantum superposition of thermodynamic evolutions with opposing time’s arrows

Author(s)
Giulia Rubino, Gonzalo Manzano, Caslav Brukner
Abstract

Microscopic physical laws are time-symmetric, hence, a priori there exists no preferential temporal direction. However, the second law of thermodynamics allows one to associate the “forward” temporal direction to a positive variation of the total entropy produced in a thermodynamic process, and a negative variation with its “time-reversal” counterpart. This definition of a temporal axis is normally considered to apply in both classical and quantum contexts. Yet, quantum physics admits also superpositions between forward and time-reversal processes, whereby the thermodynamic arrow of time becomes quantum-mechanically undefined. In this work, we demonstrate that a definite thermodynamic time’s arrow can be restored by a quantum measurement of entropy production, which effectively projects such superpositions onto the forward (time-reversal) time-direction when large positive (negative) values are measured. Finally, for small values (of the order of plus or minus one), the amplitudes of forward and time-reversal processes can interfere, giving rise to entropy-production distributions featuring a more or less reversible process than either of the two components individually, or any classical mixture thereof.

Organisation(s)
Quantum Optics, Quantum Nanophysics and Quantum Information
External organisation(s)
Vienna Center for Quantum Science and Technology (VCQ), University of Bristol, University of the Balearic Islands, Österreichische Akademie der Wissenschaften (ÖAW)
Journal
Communications Physics
Volume
4
No. of pages
10
ISSN
2399-3650
DOI
https://doi.org/10.1038/s42005-021-00759-1
Publication date
11-2021
Peer reviewed
Yes
Austrian Fields of Science 2012
103025 Quantum mechanics, 103036 Theoretical physics
Portal url
https://ucris.univie.ac.at/portal/en/publications/quantum-superposition-of-thermodynamic-evolutions-with-opposing-times-arrows(0eabe27f-4c7d-4f6d-9636-7097a2c38fb1).html