16,340 research outputs found
Extended corresponding-states behavior for particles with variable range attractions
We propose an extension of the law of corresponding states that can be
applied to systems - such as colloidal suspensions - that have widely different
ranges of attractive interactions. We argue that, for such systems, the
``reduced'' second virial coefficient is a convenient parameter to quantify the
effective range of attraction. This procedure allows us to give a simple
definition of the effective range of attraction of potentials with different
functional forms. The advantage of the present approach is that it allows us to
estimate the relative location of the liquid-vapor and solid-fluid coexistence
curves exclusively on basis of the knowledge of the pair-potential.Comment: REVTeX, 5 pages, 2 figure
Entanglement swapping in a Franson interferometer setup
We propose a simple scheme to swap the non local correlations, characteristic
of a Franson interferometric setup, between pairs of frequency entangled
photons emitted by distinct non linear crystals in a parametric down conversion
process. Our scheme consists of two distinct sources of frequency entangled
photons. One photon of each pair is sent to a separate Mach - Zender
interferometer while the other photons of the pairs are mixed by a beam
splitter and then detected in a Ou - Mandel interferometer. For suitably
postselected joint measuremetns, the photons sent at the Mach -Zender show a
coincidence photocount statistics which depends non locally on the settings of
the two interferometers.Comment: Published on the special issue of JMO in honour of the 60th birthday
of Sir Peter Knight, FRS. Submitted to JMO on 10 February 2007. While the
present manuscript was processed an independent experimental implementation
of the same scheme discussed in our manuscript has been made bythe Geneva GAP
as described in arXiv:0704.0758v
Entanglement enhanced information transmission over a quantum channel with correlated noise
We show that entanglement is a useful resource to enhance the mutual
information of the depolarizing channel when the noise on consecutive uses of
the channel has some partial correlations. We obtain a threshold in the degree
of memory, depending on the shrinking factor of the channel, above which a
higher amount of classical information is transmitted with entangled signals
Entanglement entropy in a periodically driven quantum Ising chain
We numerically study the dynamics of entanglement entropy, induced by an
oscillating time periodic driving of the transverse field, h(t), of a
one-dimensional quantum Ising chain. We consider several realizations of h(t),
and we find a number of results in analogy with entanglement entropy dynamics
induced by a sudden quantum quench. After short-time relaxation, the dynamics
of entanglement entropy synchronises with h(t), displaying an oscillatory
behaviour at the frequency of the driving. Synchronisation in the dynamics of
entanglement entropy, is spoiled by the appearance of quasi-revivals which fade
out in the thermodynamic limit, and which we interpret using a quasi-particle
picture adapted to periodic drivings. Taking the time-average of the
entanglement entropy in the synchronised regime, we find that it obeys a volume
law scaling with the subsystem's size. Such result is reminiscent of a thermal
state or of a Generalised Gibbs ensemble of a quenched Ising chain, although
the system does not heat up towards infinite temperature as a consequence of
the integrability of the model.Comment: 6 pages, 3 figure
Thermoelectric properties of junctions between metal and strongly correlated semiconductor
We propose a junction of metal and rare-earth compound semiconductor as the
basis for a possible efficient low-temperature thermoelectric device. If an
overlayer of rare earth atoms differing from the bulk is placed at the
interface, very high values of the figure of merit ZT can be reached at low
temperature. This is due to sharp variation of the transmission coefficient of
carriers across the junction at a narrow energy range, which is intrinsically
linked to the localized character of the overlayer f-orbital.Comment: RevTeX 3.0, 4 pages, 3 postscript figures. To be published in Applied
Physics Letter
Composite quantum collision models
A collision model (CM) is a framework to describe open quantum dynamics. In
its {\it memoryless} version, it models the reservoir as
consisting of a large collection of elementary ancillas: the dynamics of the
open system results from successive "collisions" of
with the ancillas of . Here, we present a general formulation of
memoryless {\it composite} CMs, where is partitioned into the very
open system under study coupled to one or more auxiliary systems .
Their composite dynamics occurs through internal - collisions
interspersed with external ones involving and the reservoir . We show that important known instances of quantum {\it non-Markovian}
dynamics of -- such as the emission of an atom into a reservoir featuring a
Lorentzian, or multi-Lorentzian, spectral density or a qubit subject to random
telegraph noise -- can be mapped on to such {\it memoryless} composite CMs.Comment: 12 pages, 4 figure
A note on two notions of compliance
We establish a relation between two models of contracts: binary session
types, and a model based on event structures and game-theoretic notions. In
particular, we show that compliance in session types corresponds to the
existence of certain winning strategies in game-based contracts.Comment: In Proceedings ICE 2014, arXiv:1410.701
The role of auxiliary states in state discrimination with linear optical evices
The role of auxiliary photons in the problem of identifying a state secretly
chosen from a given set of L-photon states is analyzed. It is shown that
auxiliary photons do not increase the ability to discriminate such states by
means of a global measurement using only optical linear elements, conditional
transformation and auxiliary photons.Comment: 5 pages. 1 figure. RevTex documen
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