28 research outputs found
Most energetic passive states
Passive states are defined as those states that do not allow for work
extraction in a cyclic (unitary) process. Within the set of passive states,
thermal states are the most stable ones: they maximize the entropy for a given
energy, and similarly they minimize the energy for a given entropy. Here we
find the passive states lying in the other extreme, i.e., those that maximize
the energy for a given entropy, which we show also minimize the entropy when
the energy is fixed. These extremal properties make these states useful to
obtain fundamental bounds for the thermodynamics of finite-dimensional quantum
systems, which we show in several scenarios.Comment: 6 pages, 2 figures; published versio
Extractable Work from Correlations
Work and quantum correlations are two fundamental resources in thermodynamics
and quantum information theory. In this work we study how to use correlations
among quantum systems to optimally store work. We analyse this question for
isolated quantum ensembles, where the work can be naturally divided into two
contributions: a local contribution from each system, and a global contribution
originating from correlations among systems. We focus on the latter and
consider quantum systems which are locally thermal, thus from which any
extractable work can only come from correlations. We compute the maximum
extractable work for general entangled states, separable states, and states
with fixed entropy. Our results show that while entanglement gives an advantage
for small quantum ensembles, this gain vanishes for a large number of systems.Comment: 5+6 pages; 1 figure. Some minor changes, close to published versio