326,489 research outputs found

### Quantum Thermodynamics

Quantum thermodynamics addresses the emergence of thermodynamical laws from
quantum mechanics. The link is based on the intimate connection of quantum
thermodynamics with the theory of open quantum systems. Quantum mechanics
inserts dynamics into thermodynamics giving a sound foundation to
finite-time-thermodynamics. The emergence of the 0-law I-law II-law and III-law
of thermodynamics from quantum considerations is presented. The emphasis is on
consistence between the two theories which address the same subject from
different foundations. We claim that inconsistency is the result of faulty
analysis pointing to flaws in approximations

### Can the entanglement entropy be the origin of black-hole entropy ?

Entanglement entropy is often speculated as a strong candidate for the origin
of the black-hole entropy. To judge whether this speculation is true or not, it
is effective to investigate the whole structure of thermodynamics obtained from
the entanglement entropy, rather than just to examine the apparent structure of
the entropy alone or to compare it with that of the black hole entropy. It is
because entropy acquires a physical significance only when it is related to the
energy and the temperature of a system. From this point of view, we construct a
`thermodynamics of entanglement' by introducing an entanglement energy and
compare it with the black-hole thermodynamics. We consider two possible
definitions of entanglement energy. Then we construct two different kinds of
thermodynamics by combining each of these different definitions of entanglement
energy with the entanglement entropy. We find that both of these two kinds of
thermodynamics show significant differences from the black-hole thermodynamics
if no gravitational effects are taken into account. These differences are in
particular highlighted in the context of the third law of thermodynamics.
Finally we see how inclusion of gravity alter the thermodynamics of the
entanglement. We give a suggestive argument that the thermodynamics of the
entanglement behaves like the black-hole thermodynamics if the gravitational
effects are included properly. Thus the entanglement entropy passes a
non-trivial check to be the origin of the black-hole entropy.Comment: 40 pages, Latex file, one figur

### A Schroedinger link between non-equilibrium thermodynamics and Fisher information

It is known that equilibrium thermodynamics can be deduced from a constrained
Fisher information extemizing process. We show here that, more generally, both
non-equilibrium and equilibrium thermodynamics can be obtained from such a
Fisher treatment. Equilibrium thermodynamics corresponds to the ground state
solution, and non-equilibrium thermodynamics corresponds to excited state
solutions, of a Schroedinger wave equation (SWE). That equation appears as an
output of the constrained variational process that extremizes Fisher
information. Both equilibrium- and non-equilibrium situations can thereby be
tackled by one formalism that clearly exhibits the fact that thermodynamics and
quantum mechanics can both be expressed in terms of a formal SWE, out of a
common informational basis.Comment: 12 pages, no figure

### Thermodynamics of the FRW universe at the event horizon in Palatini f(R) gravity

In an accelerated expanding universe, one can expect the existence of an
event horizon. It may be interesting to study the thermodynamics of the
Friedmann-Robertson-Walker (FRW) universe at the event horizon. Considering the
usual Hawking temperature, the first law of thermodynamics does not hold on the
event horizon. To satisfy the first law of thermodynamics, it is necessary to
redefine Hawking temperature. In this paper, using the redefinition of Hawking
temperature and applying the first law of thermodynamics on the event horizon,
the Friedmann equations are obtained in f(R) gravity from the viewpoint of
Palatini formalisn. In addition, the generalized second law (GSL) of
thermodynamics, as a measure of the validity of the theory, is investigated

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