Home

2001

2000

1999

1998

1994-97

2001

January	February	March	April	May
September	October	November	December

The colloquia will be held at 4:30 p.m in Jefferson Lab 356 with tea served at 4 p.m. [unless otherwise stated]

Top

Home

January, 2001

January 31: Wednesday, 4:30 p.m., Jefferson 356
Dr. Jacques Tempere	Harvard University	"Bose-Einstein condensation - properties of a novel superfluid, probed by path integrals"

February, 2001

February 14: Wednesday, 4:30 p.m., Jefferson 356
Dr. Federico Capasso	Lucent Technologies	Quantum Cascade Lasers for the Mid-to the Far-Infrared: from Mesoscopic Physics to Chemical Sensing [Abstract]
February 28: Wednesday, 4:30 p.m., Jefferson 356
Dr. Vladan Vuletic	Stanford University	"Cold atoms in anisotropic traps and in colored vacua"

Top

Home

March, 2001

March 14: Wednesday, 4:30 p.m., Jefferson 356
Dr. Chris Monroe	University of Michigan	"Quantum Information in Trapped Ions: From Bell's Inequality to Large-Scale Quantum Computing"
March 28: Wednesday, 4:30 p.m., Jefferson 356
Dr. Malvin Teich	Boston University	Entangled Photon Absorption"

Top

Home

April, 2001

April 11: Wednesday, 4:30 p.m., Jefferson 356
Dr. Siu Au Lee	Colorado State University	"Laser manipulation of group III atoms"
April 18: Wednesday, 4:30 p.m., Jefferson 356
Prof. Joseph Eberly	Univ. of Rochester	"What shape is your photon in?"
April 25: Wednesday, 4:30 p.m., Jefferson 356
Dr. Steve Rolston	NIST	"BEC + Atom Optics = Quantum Atom Optics?"

Top

Home

May, 2001

May 9: Wednesday, 4:30 p.m., Jefferson 356
Prof. Henk Stoof	Univ. of Utrecht	"Fluctuations and Noise in a Bose Condensed Gas"

September, 2001

September 19: Wednesday, 4:30 p.m., Jefferson 356
Prof. Mara Prentiss	Harvard University	"Tightly Confining Atom Waveguides"
September 26: Wednesday, 4:30 p.m., Jefferson 356
CANCELLED  Prof. Victor Flambaum	University of New South Wales	"Do the Fundamental Constants of Nature Vary with Time and Distance? (postponed to November 28)

Top

Home

October, 2001

October 3, Wednesday, 4:30 p.m., Jefferson 356
Prof. Michael Chapman	Georgia Tech	"Bose-Einstein condensation in an optical trap"
October 17, Wednesday, 4:30 p.m., Jefferson 356
Jonathan Weinstein	Harvard University	"Evaportive cooling of chromium atoms"
October 31, Wednesday, 4:30 p.m., Jefferson 356
Dr. David Wineland	NIST	Quantum information processing with trapped atomic ions" [Abstract]

Top

Home

November, 2001

November 14, Wednesday, 4:30 p.m., Jefferson 356
Dr. Wojciech Zurek	Los Alamos	Sub-Planck Scales in Phase Space and Their Relevance to Quantum Decoherence"
November 28, Wednesday, 4:30 p.m., Jefferson 356
Prof. Victor Flambaum	University of New South Wales	"Do the Fundamental Constants of Nature Vary with Time and Distance? [Abstract]

Top

Home

December, 2001

December 12, Wednesday, 4:30 p.m., Jefferson 356
Dr. Phil Hemmer	Hanscom AF Base	"Ultra-Slow and Stopped Light in Solids"

Top

Home

Abstracts

Quantum Cascade Lasers for the Mid-to the Far-Infrared: from Mesoscopic Physics to Chemical Sensing Federico Capasso Bell Laboratories Lucent Technologies Murray Hill NJ 07974 Quantum Cascade Lasers (QCL) are a fundamentally new class of semiconductor lasers in that: (1) the wavelength can be tailored across the complete mid-infrared spectrum (3-20 micron) by varying layer thickness using the same combination of materials; (2) an injected electron gives rise to a cascade of 25-75 laser photons, depending on the number of stages, leading to very high power. QCLs are an excellent example of new man-made materials and mesoscopic structures for electrons and photons built by design of their wavefunctions, optical matrix elements and scattering rates. Fundamental physical limits such as the ultimate linewidth of these lasers will be discussed along with a broad range of structures exhibiting new phenomena. These structures include surface plasmon lasers, chaotic whispering gallery lasers and bow-tie laser emission in an optical stadium, laser action by oscillator strength tuning, dual-wavelength laser emission, cascaded optical transitions and a new type of self-modelocking that has yielded picosecond pulses at higher rep-rates. The last part of the talk will deal with the use of QC lasers in high-resolution spectroscopy and chemical sensing applications at parts-per-billion level in volume. QC lasers have broad potential for the latter in light of the pulse room temperature operation and their broad single-mode tuning.

Top

Home

Quantum Information Processing with Trapped Atomic Ions Dave Wineland NIST Boulder, CO Now that the hype for quantum computing has begun to subside, it is generally agreed that building a quantum computer capable of useful number-factoring or database-searching will be an extremely difficult task. Although atomic physics experiments can satisfy many of the requirements for a quantum computer including a path to a large-scale device, difficult technical problems must be overcome. Some of these in the context of trapped ions will be discussed. In the meantime, the ideas of quantum information processing have clarified our thinking about simpler tasks, some of which can now be implemented. For example, simple quantum processing can now increase signal-to-noise ratio in spectroscopy and may broaden the choices of atoms that can be used for atomic clocks.

Top

Home

DO THE FUNDAMENTAL CONSTANTS OF NATURE VARY WITH TIME AND DISTANCE? V.V. Flambaum School of Physics University of New South Wales Abstract: Were the laws of nature the same ten billion light years away from us? A change in the fine structure constant alpha=e^2/hc could be detected via shifts in the rest wavelengths of resonance transitions in quasar absorption systems. We have developed a new approach which improves the sensitivity of this method by an order of magnitude (the effect that we study is 10 times larger than that studied in the previous works, see Phys. Rev. Lett. 82, 888, 1999). We have measured the fine structure constant in 140 absorption systems covering look-back times from 0.2 to 0.9 times the age of the Universe. Theories unifying gravity with other interactions predict the spatial and temporal variation of the fundamental "constants" in the Universe. Current interest is high because in superstring theories, which have additional spatial dimensions compactified on tiny scales, any variation of the mean size of the extra dimensions results in changes of the 3-dimensional observed coupling constants. Also, we can now probe variations at the level predicted in inflationary models of the Universe. Our initial results hinted that alpha may have been smaller in the past (Phys. Rev. Lett., 82, 884, 1999). Startlingly, new results based on 3 independent data sets support the same effect (Phys. Rev. Lett. 87, 091301, 2001 and current work).

Top

Home