1,565 research outputs found
Scalable Ellipsoidal Classification for Bipartite Quantum States
The Separability Problem is approached from the perspective of Ellipsoidal
Classification. A Density Operator of dimension N can be represented as a
vector in a real vector space of dimension , whose components are the
projections of the matrix onto some selected basis. We suggest a method to test
separability, based on successive optimization programs. First, we find the
Minimum Volume Covering Ellipsoid that encloses a particular set of properly
vectorized bipartite separable states, and then we compute the Euclidean
distance of an arbitrary vectorized bipartite Density Operator to this
ellipsoid. If the vectorized Density Operator falls inside the ellipsoid, it is
regarded as separable, otherwise it will be taken as entangled. Our method is
scalable and can be implemented straightforwardly in any desired dimension.
Moreover, we show that it allows for detection of Bound Entangled StatesComment: 8 pages, 5 figures, 3 tables. Revised version, to appear in Physical
Review
The role of quantum measurement in stochastic thermodynamics
This article sets up a new formalism to investigate stochastic thermodynamics
in the quantum regime, where stochasticity and irreversibility primarily come
from quantum measurement. In the absence of any bath, we define a purely
quantum component to heat exchange, that corresponds to energy fluctuations
caused by measurement back-action. Energetic and entropic signatures of
measurement induced irreversibility are then investigated for canonical
experiments of quantum optics, and the energetic cost of counter-acting
decoherence is characterized on a simple state-stabilizing protocol. By placing
quantum measurement in a central position, our formalism contributes to bridge
a gap between experimental quantum optics and quantum thermodynamics
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