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Displaying 76 - 100 of 154

Effects of Inhomogeneity on the Spectrum of the Mott-Insulator State

December 1, 2003
Author(s)
G Pupillo, Eite Tiesinga, Carl J. Williams
We investigate the existence of quantum quasi phase transitions for an ensemble of ultracold bosons in a one-dimensional optical lattice, performing exact diagonalizations of the Bose-Hubbard Hamiltonian. When an external parabolic potential is added to

Purely-Long-Range Bound States of He (2s 3 S) + He(2p 3 P)

August 1, 2003
Author(s)
V Venturi, P J. Leo, Eite Tiesinga, Carl J. Williams, I B. Whittingham
We predict the presence and positions of purely-long-range bound states of 4He (2s3S) + 4He (2p3P) near the2s3S1 + 2p3P0, 1 atomic limits. The results of the full multichannel and approximate models are compared, and we assess the sensitivity of the bound

Quantum Information With Neutral Atoms as Qubits

July 1, 2003
Author(s)
James V. Porto, S L. Rolston, B L. Tolra, Carl J. Williams, William D. Phillips
Neutral atoms trapped in periodic optical potentials (optical lattices) offer a possible route toward quantum computation. The atoms can be kept well isolated from the environment, yet can be easily manipulated with the tools of atomic physics. This paper

Quantum Information With Neutral Atoms as Quibits

July 1, 2003
Author(s)
James V. Porto, S L. Rolston, B L. Tolra, Carl J. Williams, William D. Phillips
One of the essential features of a quantum computer is a quantum register of well-characterized qubits. Neural atoms in optical lattices are a natural candidate for such a register. We have demonstrated a pattern loading technique that can be used to load

Quantum Computer Architecture Using Nonlocal Interactions

May 1, 2003
Author(s)
G K. Brennen, D Song, Carl J. Williams
Several authors have described the basic requirements essential to building a scalable quantum computer. Because many physical implementation schemes for quantum computing rely on nearest neighbor interactions, there is a hidden quantum communication

Quantum-Computer Architecture Using Nonlocal Interactions

May 1, 2003
Author(s)
G K. Brennen, D Song, Carl J. Williams
Many protocols for quantum information processing use a control sequence or circuit of interactions between qubits and control fields wherein arbitrary qubits can be made to interact with one another. The primary problem with many ''physically scalable

Optimizing the Fast Rydberg Quantum Gate

April 1, 2003
Author(s)
M S. Safronova, Carl J. Williams, Charles W. Clark
The fast phase gate scheme, in which the qubits are atoms confined in sites of an optical lattice, and gate operations are mediated by excitation of Rydberg states, was proposed by Jaksch et al. Phys. Rev. Lett. 85, 2208 (2000). A potential source of

Decay and Revival of Phase Coherence of a Bose-Einstein Condensate in a One-Dimensional Lattice

March 1, 2003
Author(s)
O Morsch, J H. Muller, D Ciampini, M Cristiani, P B. Blakie, Carl J. Williams, Paul S. Julienne, E Arimondo
The mode structure of a Bose-Einstein condensate non-adiabatically loaded into a one-dimensional optical lattice is studied by analyzing the visibility of the interference pattern as well as the radial profile of the condensate after a time-of-flight. A

Bogoliubov Approach to Superfluidity of Atoms in an Optical Lattice

January 1, 2003
Author(s)
A M. Rey, Karen G. Burnett, R Roth, M Edwards, Carl J. Williams, Charles W. Clark
We use the Bogoliubov theory of atoms in an optical lattice to the study the approach to the Mott-insulator transition. We derive an explicit expression for the superfluid density based on the rigidity of the system under phase variations. This enables us

High-Speed Quantum Communication Testbed

December 1, 2002
Author(s)
Carl J. Williams, Xiao Tang, M Hiekkero, J Rouzard, R Lu, A Goedecke, Alan L. Migdall, Alan Mink, Anastase Nakassis, Leticia S. Pibida
We describe the current status of the NIST Quantum Communication Testbed (QCT) facility. QCT is a facility for exploring quantum communication in an enviornment similar to that projected for early commercial implementations: quantum cryptographic key

Intensity Effects in Ultracold Photoassociation Line Shapes

December 1, 2002
Author(s)
A Simoni, Paul S. Julienne, Eite Tiesinga, Carl J. Williams
We derive ultracold atom-atom photoassociation line shapes valid for intense light fields and investigate laser power effects in sodium and rubidium photoassociation to the purely long range 0g- symmetry state. We consider intensities up to few hundreds W

Flat-Phase Loading of a Bose-Einstein Condensate into an Optical Lattice

November 1, 2002
Author(s)
S E. Sklarz, I Friedler, D J. Tannor, Y B. Band, Carl J. Williams
It has been proposed that the adiabatic loading of a Bose-Einstein Condensate into an optical lattice via the Mott-Insulator transition can be used to initialize a quantum computer [D.Jaksch, et al., Phys. Rev. Lett. 81, 3108 (1998)]. The loading of a Bose

Photodissociation Spectroscopy of Stored CH + Ions: Detection, Assignment and Close-Coupled Modeling of Near-Threshold Feshbach Resonances

November 1, 2002
Author(s)
U Hechtfischer, Carl J. Williams, J Lange, J Linkemann, D Schwalm, R Wester, A Wolf, D Zajfman
We have measured and theoretically analyzed a photodissociation spectrum of the CH + molecular ion in which most observed energy levels lie within the fine-structure splitting of the C + fragment and predissociate, with the observed irregular lineshapes