25,862 research outputs found
Oscillations of atomic fermions in a one dimensional optical lattice
A semiclassical model is used to investigate oscillations of atomic fermions
in a combined magnetic trap and one dimensional optical lattice potential
following axial displacement of the trap. The oscillations are shown to have a
characteristic small amplitude, damped behavior in the collisionless regime.
The presence of a separatrix in the semiclassical Brillouin zone phase space is
predicted and shown to produce a strongly asymmetric phase space distribution
function.Comment: 6 pages, 6 figure
Amplitude squeezed light from a laser
Intensity squeezed light was successfully generated using semiconductor lasers with sub-Poissonian pumping. Control of the pumping statistics is crucial and is achieved by a large series resistor which regulates the pump current; its sub-Poissonian statistics are then transferred to the laser output. The sub-Poissonian pumping of other laser systems is not so simple, however, and their potential as squeezed states sources is apparently diminished. We consider a conventional laser incoherently pumped well above threshold, and allow for pump depletion of the ground state. In this regime, sub-Poissonian photon statistics and squeezed amplitude fluctuations are produced
Multiplexed Memory-Insensitive Quantum Repeaters
Long-distance quantum communication via distant pairs of entangled quantum
bits (qubits) is the first step towards more secure message transmission and
distributed quantum computing. To date, the most promising proposals require
quantum repeaters to mitigate the exponential decrease in communication rate
due to optical fiber losses. However, these are exquisitely sensitive to the
lifetimes of their memory elements. We propose a multiplexing of quantum nodes
that should enable the construction of quantum networks that are largely
insensitive to the coherence times of the quantum memory elements.Comment: 5 pages, 4 figures. Accepted for publication in PR
Dephasing dynamics of Rydberg atom spin waves
A theory of Rydberg atom interactions is used to derive analytical forms for
the spin wave pair correlation function in laser-excited cold-atom vapors. This
function controls the quantum statistics of light emission from dense,
inhomogeneous clouds of cold atoms of various spatial dimensionalities. The
results yield distinctive scaling behaviors on the microsecond timescale,
including generalized exponential decay. A detailed comparison is presented
with a recent experiment on a cigar-shaped atomic ensemble [Y. Dudin and A.
Kuzmich, Science 336, 887 (2012)], in which Rb atoms are excited to a set of
Rydberg levels.Comment: 4 pages, Supplemental Material in Appendix, 4 figure
The Paraldor Project
Paraldor is an experiment in bringing the power of categorical languages to
lattice QCD computations. Our target language is Aldor, which allows the
capture of the mathematical structure of physics directly in the structure of
the code using the concepts of categories, domains and their
inter-relationships in a way which is not otherwise possible with current
popular languages such as Fortran, C, C++ or Java. By writing high level
physics code portably in Aldor, and implementing switchable machine dependent
high performance back-ends in C or assembler, we gain all the power of
categorical languages such as modularity, portability, readability and
efficiency.Comment: 4 pages, 2 figures, Lattice 2002 conference proceeding
High power coupled CO2 waveguide laser array
A hollow-bore ridge waveguide technique for phase locking arrays of coupled CO2 rf excited waveguide lasers was demonstrated. Stable phase-locked operation of two- and three-channel arrays has been demonstrated at the 50 W output level. Preliminary experiments with a five-element array generated an output power of 95 W but phase-locked operation was not conclusively demonstrated
Entanglement of light-shift compensated atomic spin waves with telecom light
Entanglement of a 795 nm light polarization qubit and an atomic Rb spin wave
qubit for a storage time of 0.1 s is observed by measuring the violation of
Bell's inequality (S = 2.65 \pm 0.12). Long qubit storage times are achieved by
pinning the spin wave in a 1064 nm wavelength optical lattice, with a
magic-valued magnetic field superposed to eliminate lattice-induced dephasing.
Four-wave mixing in a cold Rb gas is employed to perform light qubit conversion
between near infra red (795 nm) and telecom (1367 nm) wavelengths, and after
propagation in a telecom fiber, to invert the conversion process. Observed Bell
inequality violation (S = 2.66 \pm 0.09), at 10 ms storage, confirms
preservation of memory/light entanglement through the two stages of light qubit
frequency conversion.Comment: 5 pages, 3 figure
Quantum interference of electromagnetic fields from remote quantum memories
We observe quantum, Hong-Ou-Mandel, interference of fields produced by two
remote atomic memories. High-visibility interference is obtained by utilizing
the finite atomic memory time in four-photon delayed coincidence measurements.
Interference of fields from remote atomic memories is a crucial element in
protocols for scalable generation of multi-node remote qubit entanglement.Comment: 4 pages, 3 figure
- …