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Search Publications by: Charles W Clark (Assoc)

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Displaying 51 - 75 of 447

Experimental Study of High Speed Polarization -Coding Quantum Key Distribution with Sifted -Key Rates Over Mbit/s

June 1, 2009
Author(s)
Xiao Tang, Lijun Ma, Alan Mink, Anastase Nakassis, Barry J. Hershman, Joshua C. Bienfang, David H. Su, Ronald F. Boisvert, Charles W. Clark, Carl J. Williams
We have demonstrated a polarization encoded, fiber-based quantum key distribution system operating at 850 nm in the B92 protocol. With a quantum bit transmission rate i.e. optical pulse driving frequency of 625 MHz and a mean photon number of 0.1, we

Quantum Key Distribution System Operating at Sifted-Key Rate Over 4 Mbit/s 1

June 1, 2009
Author(s)
Xiao Tang, Lijun Ma, Alan Mink, Anastase Nakassis, Hai Xu, Barry J. Hershman, Joshua C. Bienfang, David H. Su, Ronald F. Boisvert, Charles W. Clark, Carl J. Williams
A complete fiber-based polarization encoding quantum key distribution (QKD) system based on the BB84 protocol has been developed at National Institute of Standard and Technology (NIST). The system can be operated at a sifted key rate of more than 4 Mbit/s

Topological Insulators and Metals in Atomic Optical Lattices

May 28, 2009
Author(s)
Tudor Stanescu, Victor Galitski, Jay Vaishnav, Charles W. Clark, Sankar Das Sarma
We propose the realization of topological quantum states with cold atoms trapped in an optical lattice. We discuss an experimental setup that generates a two-dimensional hexagonal lattice in the presence of a light-induced periodic vector potential, which

Measurement of Small Birefringence and Loss in a Nonlinear Single-mode Waveguide

May 11, 2009
Author(s)
Daniel Rogers, Charles W. Clark, Christopher Richardson, Julius Goldhar
We design and fabricate a birefringent semiconductor waveguide for application to nonlinear photonics, demonstrating that it is possible to engineer a small birefringence into such a device using multiple core layers. We also demonstrate a simple technique

Phase transitions, entanglement and quantum noise interferometry in cold atoms

March 5, 2009
Author(s)
F. Mintert, A.M. Rey, Indubala I. Satija, Charles W. Clark
We show that entanglement monotones can characterize the pronounced enhancement of entanglement at a quantum phase transition if they are sensitive to long-range high order correlations. These monotones are found to develop a sharp peak at the critical

Creating a supersolid in one-dimensional Bose mixtures

January 15, 2009
Author(s)
Ludwig G. Mathey, Ippei Danshita, Charles W. Clark
We identify a one-dimensional supersolid phase in a binary mixture of near-hardcore bosons with weak, local interspecies repulsion. We find realistic conditions under which such a phase, defined here as the coexistence of quasi-superfluidity and quasi

Non-quantization of Current in an Annular Bose-Einstein Condensate

October 16, 2008
Author(s)
D L. Feder, L A. Collins, Charles W. Clark
The circulating states of a Bose-Einstein condensate confined in an annulus are investigated both analytically and numerically. It is demonstrated that while single-valuedness of the condensate wavefunction ensures the quantization of circulation in this

Quantum key distribution at GHz transmission rates

February 11, 2008
Author(s)
Alessandro Restelli, Joshua C. Bienfang, Alan Mink, Charles W. Clark
Quantum key distribution (QKD) channels are typically realized by transmitting and detecting single photons, and therefore suffer from dramatic reductions in throughput due to both channel loss and noise. These shortcomings can be mitigated by applying

Pseudo-Fermionization of 1-D Bosons in Optical Lattices

February 2, 2008
Author(s)
G Pupillo, A M. Rey, Carl J. Williams, Charles W. Clark
We present a model that generalizes the Bose-Fermi mapping for strongly correlated 1D bosons in an optical lattice, to cases in which the average number of atoms per site is larger than one. This model gives an accurate account of equilibrium properties of

Magic Wavelengths for the np - ns Transitions in Alkali-Metal Atoms

November 15, 2007
Author(s)
B Arora, M S. Safronova, Charles W. Clark
Extensive calculations of the electric-dipole matrix elements in alkali-metal atoms are conducted using the relativistic all-order method. This approach is a linearized version of the coupled-cluster method, which sums infinite sets of many-body