4,159 research outputs found
Quantum Entanglement in Nanocavity Arrays
We show theoretically how quantum interference between linearly coupled modes
with weak local nonlinearity allows the generation of continuous variable
entanglement. By solving the quantum master equation for the density matrix, we
show how the entanglement survives realistic levels of pure dephasing. The
generation mechanism forms a new paradigm for entanglement generation in arrays
of coupled quantum modes.Comment: 5 pages, 3 figure
Artificial Life in an Exciton-Polariton Lattice
We show theoretically that a lattice of exciton-polaritons can behave as a
life-like cellular automaton when simultaneously excited by a continuous wave
coherent field and a time-periodic sequence of non-resonant pulses. This
provides a mechanism of realizing a range of highly sought spatiotemporal
structures under the same conditions, including: discrete solitons, oscillating
solitons, rotating solitons, breathers, soliton trains, guns, and choatic
behaviour. These structures can survive in the system indefinitely, despite the
presence of dissipation, and allow universal computation.Comment: 14 pages, 14 figure
Exciton-Polariton Quantum Gates Based on Continuous Variables
We propose a continuous variable analog of quantum controlled-NOT gates based
on a system of exciton-polaritons in semiconductor microcavities. This can be
realized by the engineering of parametric interaction between control and
target polariton modes, which can be varied in time. As an explicit setup we
use a system of dipolaritons, which allows for enhancement of parametric
interaction by auxiliary classical fields and scalable multigate system
realization. The calculated fidelity is shown to exceed 99% for realistic
system parameters.Comment: 6 pages, 3 figures + 6 pages, 2 figures supplemental materia
Spontaneous and Superfluid Chiral Edge States in Exciton-Polariton Condensates
We present a scheme of interaction-induced topological bandstructures based
on the spin anisotropy of exciton-polaritons in semiconductor microcavities. We
predict theoretically that this scheme allows the engineering of topological
gaps, without requiring a magnetic field or strong spin-orbit interaction
(transverse electric-transverse magnetic splitting). Under non-resonant
pumping, we find that an initially topologically trivial system undergoes a
topological transition upon the spontaneous breaking of phase symmetry
associated with polariton condensation. Under resonant coherent pumping, we
find that it is also possible to engineer a topological dispersion that is
linear in wavevector -- a property associated with polariton superfluidity.Comment: 6 pages, 4 figure
Single photons from coupled quantum modes
Single photon emitters often rely on a strong nonlinearity to make the
behaviour of a quantum mode susceptible to a change in the number of quanta
between one and two. In most systems the strength of nonlinearity is weak, such
that changes at the single quantum level have little effect. Here, we consider
coupled quantum modes and and that they can be strongly sensitive at the single
quantum level, even if nonlinear interactions are modest. As examples, we
consider solid-state implementations based on the tunneling of polaritons
between quantum boxes or their parametric modes in a microcavity. We find that
these systems can act as promising single photon emitters.Comment: 4 pages, 3 figure
Single photons from a gain medium below threshold
The emission from a nonlinear photonic mode coupled weakly to a gain medium
operating below threshold is predicted to exhibit antibunching. In the steady
state regime, analytical solutions for the relevant observable quantities are
found in accurate agreement with exact numerical results. Under pulsed
excitation, the unequal time second order correlation function demonstrates the
triggered probabilistic generation of single photons well separated in time.Comment: Submitte
Optically erasing disorder in semiconductor microcavities with dynamic nuclear polarization
The mean squared value of the photonic disorder is found to be reduced by a
factor of 100 in a typical GaAs based microcavity, when exposed to a circularly
polarized continuous wave optical pump without any special spatial patterning.
Resonant excitation of the cavity mode excites a spatially non-uniform
distribution of spin-polarized electrons, which depends on the photonic
disorder profile. Electrons transfer spin to nuclei via the hyperfine contact
interaction, inducing a long-living Overhauser magnetic field able to modify
the potential of exciton-polaritons.Comment: 4 pages, 3 figure
Quantum Exciton-Polariton Networks through Inverse Four-Wave Mixing
We demonstrate the potential of quantum operation using lattices of
exciton-polaritons in patterned semiconductor microcavities. By introducing an
inverse four-wave mixing scheme acting on localized modes, we show that it is
possible to develop non-classical correlations between individual condensates.
This allows a concept of quantum exciton-polariton networks, characterized by
the appearance of multimode entanglement even in the presence of realistic
levels of dissipation.Comment: 5 pages, 4 figures, pre-review version of manuscrip
Optically induced transparency in bosonic cascade lasers
Bosonic cascade lasers are terahertz (THz) lasers based on stimulated
radiative transitions between bosonic condensates of excitons or
exciton-polaritons confined in a trap. We study the interaction of an incoming
THz pulse resonant in frequency with the transitions between neighboring energy
levels of the cascade. We show that at certain optical pump conditions the
cascade becomes transparent to the incident pulse: it neither absorbs nor
amplifies it, in the mean field approximation. The populations of intermediate
levels of the bosonic cascade change as the THz pulse passes, nevertheless. In
comparison, a fermionic cascade laser does not reveal any of these properties.Comment: 4 pages, 5 figure
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