17,984 research outputs found
Mesoscopic Superposition of States with Sub-Planck Structures in Phase Space
We propose a method using the dispersive interaction between atoms and a high
quality cavity to realize the mesoscopic superposition of coherent states which
would exhibit sub-Planck structures in phase space. In particular we focus on a
superposition involving four coherent states. We show interesting interferences
in the conditional measurements involving two atoms.Comment: 4-page 3-figur
Exactly solvable -symmetric models in two dimensions
Non-hermitian, -symmetric Hamiltonians, experimentally realized
in optical systems, accurately model the properties of open, bosonic systems
with balanced, spatially separated gain and loss. We present a family of
exactly solvable, two-dimensional, potentials for a
non-relativistic particle confined in a circular geometry. We show that the
symmetry threshold can be tuned by introducing a second
gain-loss potential or its hermitian counterpart. Our results explicitly
demonstrate that breaking in two dimensions has a rich phase
diagram, with multiple re-entrant symmetric phases.Comment: 6 pages, 6 figure
Cosmic acceleration from coupling of baryonic and dark matter components: Analysis and diagnostics
In this paper, we examine a scenario in which late-time cosmic acceleration
might arise due to the coupling between baryonic matter and dark matter without
the presence of extra degrees of freedom. In this case, one can obtain
late-time acceleration in Jordan frame and not in Einstein frame. We consider
two different forms of parametrization of the coupling function, and put
constraints on the model parameters by using an integrated datasets of Hubble
parameter, Type Ia supernova and baryon acoustic oscillations. The models under
consideration are consistent with the observations. In addition, we perform the
statefinder and diagnostics, and show that the models exhibit a
distinctive behavior due to the phantom characteristic in future which is a
generic feature of the underlying scenario.Comment: 15 pages, 5 figure
Quantum random walk of two photons in separable and entangled state
We discuss quantum random walk of two photons using linear optical elements.
We analyze the quantum random walk using photons in a variety of quantum states
including entangled states. We find that for photons initially in separable
Fock states, the final state is entangled. For polarization entangled photons
produced by type II downconverter, we calculate the joint probability of
detecting two photons at a given site. We show the remarkable dependence of the
two photon detection probability on the quantum nature of the state. In order
to understand the quantum random walk, we present exact analytical results for
small number of steps like five. We present in details numerical results for a
number of cases and supplement the numerical results with asymptotic analytical
results
Off Resonant Pumping for Transition from Continuous to Discrete Spectrum and Quantum Revivals in Systems in Coherent States
We show that in parametrically driven systems and, more generally, in systems
in coherent states, off-resonant pumping can cause a transition from a
continuum energy spectrum of the system to a discrete one, and result in
quantum revivals of the initial state. The mechanism responsible for quantum
revivals in the present case is different from that in the non-linear
wavepacket dynamics of systems such as Rydberg atoms. We interpret the reported
phenomena as an optical analog of Bloch oscillations realized in Fock space and
propose a feasible scheme for inducing Bloch oscillations in trapped ions.Comment: 5 pages, 4 figures, submitted to Jnl. of Optics
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