4,014 research outputs found
A measure of quantum correlations that lies approximately between entanglement and discord
When a quantum system is divided into two local subsystems, measurements on
the two subsystems can exhibit correlations beyond those possible in a
classical joint probability distribution; these are partially explained by
entanglement, and more generally by a wider class of measures such as the
quantum discord. In this work, I introduce a simple thought experiment defining
a new measure of quantum correlations, which I call the accord, and write the
result as a minimax optimization over unitary matrices. I find the exact result
for pure states as a simple function of the Schmidt coefficients and provide a
complete proof, and I likewise provide and prove the result for several classes
of mixed states, notably including all states of two qubits and the
experimentally relevant case of a pure state mixed with colorless noise. I
demonstrate that for two qubit states the accord provides a tight lower bound
on the discord; for Bell diagonal states it is also an upper bound on
entanglement.Comment: 15 pages, 5 figures; v2: removed claim of convexity, all other
results unchanged; v3: typo-level correction
The adjoint potential in the pseudoparticle approach: string breaking and Casimir scaling
We perform a detailed study of the adjoint static potential in the
pseudoparticle approach, which is a model for SU(2) Yang-Mills theory. We find
agreement with the Casimir scaling hypothesis and there is clear evidence for
string breaking. At the same time the potential in the fundamental
representation is linear for large separations. Our results are in qualitative
agreement with results from lattice computations.Comment: 5 pages, 2 figures, talk given at "Quark Confinement and the Hadron
Spectrum VIII", September 1 - 6 2008, Mainz, German
Lorentz Process with shrinking holes in a wall
We ascertain the diffusively scaled limit of a periodic Lorentz process in a
strip with an almost reflecting wall at the origin. Here, almost reflecting
means that the wall contains a small hole waning in time. The limiting process
is a quasi-reflected Brownian motion, which is Markovian but not strong
Markovian. Local time results for the periodic Lorentz process, having
independent interest, are also found and used
Considering skin physiology in capacitive-coupled hyperthermia
Dominant technical solution for oncological hyperthermia devices is capacitive-coupling. However, it has the challenge of overheating the surface of adipose layers and burning cutaneous structures. The main technical solution of this is the intensive cooling of the surface. Our objective is studying the physiology and effect of the active cooling of the skin in capacitive-coupled hyperthermia technologies
Note on Phase Space Contraction and Entropy Production in Thermostatted Hamiltonian Systems
The phase space contraction and the entropy production rates of Hamiltonian
systems in an external field, thermostatted to obtain a stationary state are
considered. While for stationary states with a constant kinetic energy the two
rates are formally equal for all numbers of particles N, for stationary states
with constant total (kinetic and potential) energy this only obtains for large
N. However, in both cases a large number of particles is required to obtain
equality with the entropy production rate of Irreversible Thermodynamics.
Consequences of this for the positivity of the transport coefficients and for
the Onsager relations are discussed. Numerical results are presented for the
special case of the Lorentz gas.Comment: 16 pages including 1 table and 3 figures. LaTeX forma
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