PIRSA:20110060

Time's Arrow of a Quantum Superposition of Thermodynamic Evolutions

Rubino, G. (2020). Time's Arrow of a Quantum Superposition of Thermodynamic Evolutions. Perimeter Institute. https://pirsa.org/20110060

Rubino, Giulia. Time's Arrow of a Quantum Superposition of Thermodynamic Evolutions. Perimeter Institute, Nov. 27, 2020, https://pirsa.org/20110060 

          @misc{ pirsa_PIRSA:20110060,
            doi = {10.48660/20110060},
            url = {https://pirsa.org/20110060},
            author = {Rubino, Giulia},
            keywords = {Quantum Foundations},
            language = {en},
            title = {Time{\textquoteright}s Arrow of a Quantum Superposition of Thermodynamic Evolutions},
            publisher = {Perimeter Institute},
            year = {2020},
            month = {nov},
            note = {PIRSA:20110060 see, \url{https://pirsa.org}}
          }

Giulia Rubino

Institute for Quantum Optics and Quantum Information (IQOQI) - Vienna

Talk number
PIRSA:20110060
Collection
Talk Type
Subject
Abstract

A priori, there exists no preferential temporal direction as microscopic physical laws are time-symmetric. Still, 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, thereby seemingly eluding conventional definitions of time's arrow. In this talk, I will demonstrate that a quantum measurement of entropy production can distinguish the two temporal directions, effectively projecting such superpositions of thermodynamic processes onto the forward (time-reversal) time-direction when large positive (negative) values are measured.
Remarkably, 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.
Finally, I will extend these concepts to the case of a thermal machine running in a superposition of the heat engine and the refrigerator mode, illustrating how such interference effects can be employed to reduce undesirable fluctuations.