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Search Publications by: Charles W Clark (Assoc)

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Displaying 26 - 50 of 435

Far-ultraviolet signatures of the 3He(n,tp) reaction in noble gas mixtures

December 8, 2010
Author(s)
Patrick Hughes, Alan K. Thompson, Michael Coplan, Robert E. Vest, Charles W. Clark
Previous work showed that the 3He(n,tp) reaction in a cell of 3He at atmospheric pressure generated tens of far-ultraviolet photons per reacted neutron. Here we report amplification of that signal by factors of 1000 and more when noble gases are added to

A Green Laser Pointer Hazard

August 2, 2010
Author(s)
Jemellie Galang, Alessandro Restelli, Edward W. Hagley, Charles W. Clark
An inexpensive green laser pointer was found to emit 20 mW of infrared radiation during normal use. This is potentially a serious hazard that would not be noticed by most users of such pointers. We find that the problem derives from an unsafe design, and

Ettore Majorana and the birth of autoionization

July 2, 2010
Author(s)
Charles W. Clark, Ennio Arimondo, William C. Martin
In the early days of theoretical atomic spectroscopy, Ettore Majorana (1906-1938?) solved several outstanding problems by developing the theory of autoionization. Later literature makes only sporadic references to this accomplishment. Reviewing his work in

The NIST Handbook of Mathematical Functions

May 12, 2010
Author(s)
Frank W. Olver, Daniel W. Lozier, Ronald Boisvert, Charles W. Clark
The NIST Handbook of Mathematical Functions supplies validated reference information in 36 chapters on a wide selection of important mathematical functions, covering the properties necessary for their use in scientific applications, together with general

RECIST vs. Volume Measurement in Medical CT Using Ellipsoids of Known Size

April 12, 2010
Author(s)
Zachary H. Levine, Bruce R. Borchardt, Nolan J. Brandenburg, Charles W. Clark, Balasubramanian Muralikrishnan, Craig M. Shakarji, Joseph J. Chen, Eliot L. Siegel
(a) Purpose: We wanted to test the extent to which two common methods of determining the sizes of tumors would perform when compared to a statistically significant number of well-characterized reference objects. The size of the objects was chosen to

Ultracold Atom Spin Field Effect Transistor

September 14, 2009
Author(s)
Jay Vaishnav, Julius Ruseckas, Charles W. Clark, Gediminas Juzelunas
We propose a method of constructing cold atom analogs of the spintronic device known as the Datta-Das transistor (DDT), which despite its seminal conceptual role in spintronics, has never been successfully realized with electrons. We propose two

Collisional cooling of ultra-cold atom ensembles using Feshbach resonances

September 8, 2009
Author(s)
Ludwig G. Mathey, Eite Tiesinga, Paul S. Julienne, Charles W. Clark
We propose a new type of cooling mechanism for ultra-cold fermionic atom ensembles, which capitalizes on the energy dependence of inelastic collisions in the presence of a Feshbach resonance. We first discuss the case of a single magnetic resonance, and

Counterflow and paired superfluidity in one-dimensional Bose mixtures in optical lattices

August 24, 2009
Author(s)
Anzi A. Hu, Ludwig G. Mathey, Ippei Danshita, Eite Tiesinga, Carl J. Williams, Charles W. Clark
We study the quantum phases of mixtures of ultra-cold bosonic atoms held in an optical lattice that confines motion or hopping to one spatial dimension. The phases are found by using Tomonaga-Luttinger liquid theory as well as the numerical method of time

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