415 research outputs found
Absence of Long-Range Coherence in the Parametric Emission from Photonic Wires
We analytically investigate the spatial coherence properties of the signal
emission from one-dimensional optical parametric oscillators. Because of the
reduced dimensionality, quantum fluctuations are able to destroy the long-range
phase coherence even far above threshold. The spatial decay of coherence is
exponential and, for realistic parameters of semiconductor photonic wires in
the strong exciton-photon coupling regime, it is predicted to occur on an
experimentally accessible length scale.Comment: 6 pages, 3 figure
Optomechanical signature of a frictionless flow of superfluid light
We propose an experimental setup that should make it possible to reveal the
frictionless flow of a superfluid of light from the suppression of the drag
force that it exerts onto a material obstacle. In the paraxial-propagation
geometry considered here, the photon-fluid dynamics is described by a wave
equation analogous to the Gross-Pitaevskii equation of dilute Bose-Einstein
condensates and the obstacle consists in a solid dielectric slab immersed into
a nonlinear optical liquid. By means of an ab initio calculation of the
electromagnetic force experienced by the obstacle, we anticipate that
superfluidity is detectable in state-of-the-art experiments from the
disappearance of the optomechanical deformation of the obstacle.Comment: 10 pages, 4 figure
Bogoliubov Theory of acoustic Hawking radiation in Bose-Einstein Condensates
We apply the microscopic Bogoliubov theory of dilute Bose-Einstein
condensates to analyze quantum and thermal fluctuations in a flowing atomic
condensate in the presence of a sonic horizon. For the simplest case of a
step-like horizon, closed-form analytical expressions are found for the
spectral distribution of the analog Hawking radiation and for the density
correlation function. The peculiar long-distance density correlations that
appear as a consequence of the Hawking emission features turns out to be
reinforced by a finite initial temperature of the condensate. The analytical
results are in good quantitative agreement with first principle numerical
calculations.Comment: 11 pages, 7 figure
Probing few-particle Laughlin states of photons via correlation measurements
We propose methods to create and observe Laughlin-like states of photons in a
strongly nonlinear optical cavity. Such states of strongly interacting photons
can be prepared by pumping the cavity with a Laguerre-Gauss beam, which has a
well-defined orbital angular momentum per photon. The Laughlin-like states
appear as sharp resonances in the particle-number-resolved transmission
spectrum. Power spectrum and second-order correlation function measurements
yield unambiguous signatures of these few-particle strongly-correlated states.Comment: 11 pages including appendice
Dynamical Casimir Effect in Optically Modulated Cavities
Cavities with periodically oscillating mirrors have been predicted to excite
photon pairs out of the quantum vacuum in a process known as the Dynamical
Casimir effect. Here we propose and analyse an experimental layout that can
provide an efficient modulation of the effective optical length of a cavity
mode in the near-infrared spectral region. An analytical model of the dynamical
Casimir emission is developed and compared to the predictions of a direct
numerical solution of Maxwell's equations in real time. A sizeable intensity of
dynamical Casimir emission is anticipated for realistic operating parameters.
In the presence of an external coherent seed beam, we predict amplification of
the seed beam and the appearance of an additional phase-conjugate beam as a
consequence of stimulated dynamical Casimir processes.Comment: 6 pages, 5 figure
Two-body bound and edge states in the extended SSH Bose-Hubbard model
We study the bosonic two-body problem in a Su-Schrieffer-Heeger dimerized
chain with on-site and nearest-neighbor interactions. We find two classes of
bound states. The first, similar to the one induced by on-site interactions,
has its center of mass on the strong link, whereas the second, existing only
thanks to nearest-neighbors interactions, is centered on the weak link. We
identify energy crossings between these states and analyse them using exact
diagonalization and perturbation theory. In the presence of open boundary
conditions, novel strongly-localized edge-bound states appear in the spectrum
as a consequence of the interplay between lattice geometry, on-site and
nearest-neighbor interactions. Contrary to the case of purely on-site
interactions, such EBS persist even in the strongly interacting regime.Comment: 12 pages, 8 figures; Submitted to EPJ Special Topics, Quantum Gases
and Quantum Coherenc
Multimode entanglement in coupled cavity arrays
We study a driven-dissipative array of coupled nonlinear optical resonators
by numerically solving the Von Neumann equation for the density matrix. We
demonstrate that quantum correlated states of many photons can be generated
also in the limit where the nonlinearity is much smaller than the losses,
contrarily to common expectations. Quantum correlations in this case arise from
interference between different pathways that the system can follow in the
Hilbert space to reach its steady state under the effect of coherent driving
fields. We characterize in particular two systems: a linear chain of three
coupled cavities and an array of eight coupled cavities. We demonstrate the
existence of a parameter range where the system emits photons with
continuous-variable bipartite and quadripartite entanglement, in the case of
the first and the second system respectively. This entanglement is shown to
survive realistic rates of pure dephasing and opens a new perspective for the
realization of quantum simulators or entangled photon sources without the
challenging requirement of strong optical nonlinearities.Comment: 20 pages, 7 figure
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