10,609 research outputs found
Bright bichromatic entanglement and quantum dynamics of sum frequency generation
We investigate the quantum properties of the well-known process of sum
frequency generation, showing that it is potentially a very useful source of
non-classical states of the electromagnetic field, some of which are not
possible with the more common techniques. We show that it can produce
quadrature squeezed light, bright bichromatic entangled states and symmetric
and asymmetric demonstrations of the Einstein-Podolsky-Rosen paradox. We also
show that the semiclassical equations totally fail to describe the mean-field
dynamics when the cavity is strongly pumped
Generation of photons from vacuum in cavity via time-modulation of a qubit invisible to the field
We propose a scheme for generation of photons from vacuum due to
time-modulation of a quantum system coupled indirectly to the cavity field
through some ancilla quantum subsystem. We consider the simplest case when the
modulation is applied to an artificial 2-level atom (we call t-qubit), while
the ancilla is a stationary qubit coupled via the dipole interaction both to
the cavity and t-qubit. We find that tripartite entangled states with a small
number of photons can be generated from the system ground state under resonant
modulations, even when the t-qubit is far detuned from both the ancilla and the
cavity, provided its bare and modulation frequencies are properly adjusted as
function of other system parameters. We attest our approximate analytic results
by numeric simulations and show that photon generation from vacuum persists in
the presence of common dissipation mechanisms
Generation of entangled photon pairs in optical cavity-QED: Operating in the bad cavity limit
We propose an optical cavity-QED scheme for the deterministic generation of
polarization entangled photon pairs that operates with high fidelity even in
the bad cavity limit. The scheme is based on the interaction of an excited
four-level atom with two empty optical cavity modes via an adiabatic passage
process. Monte-Carlo wave function simulations are used to evaluate the
fidelity of the cavity-QED source and its entanglement capability in the
presence of decoherence. In the bad cavity limit, fidelities close to one are
predicted for state-of-the-art experimental parameter values.Comment: 9 pages and 5 figure
Hybrid quantum repeater based on resonant qubit-field interactions
We propose a hybrid quantum repeater based on ancillary coherent field states
and material qubits coupled to optical cavities. For this purpose, resonant
qubit-field interactions and postselective field measurements are determined
which are capable of realizing all necessary two-qubit operations for the
actuation of the quantum repeater. We explore both theoretical and experimental
possibilities of generating near-maximally-entangled qubit pairs ()
over long distances. It is shown that our scheme displays moderately low
repeater rates, between and pairs per second, over
distances up to km, and it relies completely on current technology of
cavity quantum electrodynamics.Comment: 18 pages, 13 figures, corrected according to published Erratu
Performance of a deterministic source of entangled photonic qubits
We study the possible limitations and sources of decoherence in the scheme
for the deterministic generation of polarization-entangled photons, recently
proposed by Gheri et al. [K. M. Gheri et al., Phys. Rev. A 58, R2627 (1998)],
based on an appropriately driven single atom trapped within an optical cavity.
We consider in particular the effects of laser intensity fluctuations, photon
losses, and atomic motion.Comment: 10 pages, 6 figure
The Quantum Internet
Quantum networks offer a unifying set of opportunities and challenges across
exciting intellectual and technical frontiers, including for quantum
computation, communication, and metrology. The realization of quantum networks
composed of many nodes and channels requires new scientific capabilities for
the generation and characterization of quantum coherence and entanglement.
Fundamental to this endeavor are quantum interconnects that convert quantum
states from one physical system to those of another in a reversible fashion.
Such quantum connectivity for networks can be achieved by optical interactions
of single photons and atoms, thereby enabling entanglement distribution and
quantum teleportation between nodes.Comment: 15 pages, 6 figures Higher resolution versions of the figures can be
downloaded from the following link:
http://www.its.caltech.edu/~hjkimble/QNet-figures-high-resolutio
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