Operational definition of the temperature of a quantum state
- URL: http://arxiv.org/abs/2205.00017v2
- Date: Tue, 31 Jan 2023 10:36:35 GMT
- Title: Operational definition of the temperature of a quantum state
- Authors: Patryk Lipka-Bartosik, Mart\'i Perarnau-Llobet, Nicolas Brunner
- Abstract summary: We define two effective temperatures for the ability of a quantum system to cool down or heat up a thermal environment.
We consider a more sophisticated scenario where the heat exchange between the system and the thermal environment is assisted by a quantum reference frame.
This leads to an effect of "coherent quantum coherence", where the use of a coherent catalyst allows for exploiting quantum energetic coherences in the system.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Temperature is usually defined for physical systems at thermal equilibrium.
Nevertheless one may wonder if it would be possible to attribute a meaningful
notion of temperature to an arbitrary quantum state, beyond simply the thermal
(Gibbs) state. In this work, we propose such a notion of temperature
considering an operational task, inspired by the Zeroth Law of thermodynamics.
Specifically, we define two effective temperatures for quantifying the ability
of a quantum system to cool down or heat up a thermal environment. In this way
we can associate an operationally meaningful notion of temperature to any
quantum density matrix. We provide general expressions for these effective
temperatures, for both single- and many-copy systems, establishing connections
to concepts previously discussed in the literature. Finally, we consider a more
sophisticated scenario where the heat exchange between the system and the
thermal environment is assisted by a quantum reference frame. This leads to an
effect of "coherent quantum catalysis", where the use of a coherent catalyst
allows for exploiting quantum energetic coherences in the system, now leading
to much colder or hotter effective temperatures.
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