Scholars@Duke
John E. Thomas

John E. Thomas

Fritz London Distinguished Professor Emeritus of Physics
Physics
jet@phy.duke.edu
Box 90305, Durham, NC 27708-0305
185 Physics Bldg, Durham, NC 27708

Selected Publications

Observation of shock waves in a strongly interacting Fermi gas.

Journal Article Physical review letters · April 2011 We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a bo ... Full text Cite

Universal quantum viscosity in a unitary Fermi gas.

Journal Article Science (New York, N.Y.) · January 2011 A Fermi gas of atoms with resonant interactions is predicted to obey universal hydrodynamics, in which the shear viscosity and other transport coefficients are universal functions of the density and temperature. At low temperatures, the viscosity has a uni ... Full text Cite

Is an ultra-cold strongly interacting Fermi gas a perfect fluid

Journal Article Nucl. Phys. A · October 2009 Cite

Controlling spin current in a trapped Fermi gas.

Journal Article Physical review letters · July 2009 We study fundamental features of spin current in a very weakly interacting Fermi gas of 6Li. By creating a spin current and then reversing its flow, we demonstrate control of the spin current. This reversal is predicted by a spin vector evolution equation ... Full text Cite

Inelastic collisions of a Fermi gas in the BEC-BCS crossover.

Journal Article Physical review letters · June 2009 We measure inelastic three-body and two-body collisional decay rates for a two-component Fermi gas of 6Li, which are highly suppressed by the Pauli exclusion principle. Our measurements are made in the BEC-BCS crossover regime, near the two-body collisiona ... Full text Cite

Thermodynamic measurements in strongly interacting Fermi gas

Journal Article Journal of Low Temperature Physics · January 1, 2009 Strongly interacting Fermi gases provide a clean and controllable laboratory system for modeling strong interparticle interactions between fermions in nature, from high temperature superconductors to neutron matter and quark-gluon plasmas. Model-independen ... Full text Cite

Observation of anomalous spin segregation in a trapped Fermi gas.

Journal Article Physical review letters · October 2008 We report the observation of spin segregation, i.e., time-dependent separation of the spin density profiles of two spin states, in a trapped, coherently prepared Fermi gas of 6Li with a magnetically tunable scattering length a12 close to zero. For |a12| ap ... Full text Cite

Energy measurement and virial theorem for confined universal Fermi gases

Journal Article Physical Review A - Atomic, Molecular, and Optical Physics · July 23, 2008 Optically trapped two-component Fermi gases near a broad Feshbach resonance exhibit universal thermodynamics, where the properties of the gas are independent of the details of the two-body scattering interactions. We show that the measured cloud profiles o ... Full text Cite

Is a gas of strongly interacting atomic fermions a nearly perfect fluid?

Journal Article Journal of Low Temperature Physics · February 1, 2008 We use all-optical methods to produce a highly-degenerate Fermi gas of spin-1/2 6Li atoms. A magnetic field tunes the gas near a collisional (Feshbach) resonance, producing strong interactions between spin-up and spin-down atoms. We have measured propertie ... Full text Cite

Observation of nearly perfect irrotational flow in normal and superfluid strongly interacting Fermi gases.

Journal Article Physical review letters · October 2007 We study the hydrodynamic expansion of a rotating strongly interacting Fermi gas by releasing a cigar-shaped cloud with a known angular momentum from an optical trap. As the aspect ratio of the expanding cloud approaches unity, the angular velocity increas ... Full text Cite

Measurement of sound velocity in a fermi gas near a feshbach resonance

Journal Article Physical Review Letters · April 24, 2007 Sound waves are excited in an optically trapped degenerate Fermi gas of spin-up and spin-down atoms with magnetically tunable interactions. Measurements are made throughout the crossover region, from a weakly interacting Fermi gas through the resonant Ferm ... Full text Cite

Measurement of the entropy and critical temperature of a strongly interacting Fermi gas.

Journal Article Physical review letters · February 2007 We report a model-independent measurement of the entropy, energy, and critical temperature of a degenerate, strongly interacting Fermi gas of atoms. The total energy is determined from the mean square cloud size in the strongly interacting regime, where th ... Full text Cite

Evaporative cooling of unitary Fermi gas mixtures in optical traps

Journal Article New Journal of Physics · September 27, 2006 We measure the scaling laws for the number of atoms and the cloud size as a function of trap depth for evaporative cooling of a unitary Fermi gas in an optical trap. A unitary Fermi gas comprises a trapped mixture of atoms in two hyperfine states which is ... Full text Cite

Ultracold Fermi gas on a chip

Journal Article Nature Physics · June 2006 Full text Cite

Optically-trapped Fermi gases

Journal Article Habitation · 2006 Cite

Optically trapped Fermi gases model strong interactions in nature

Journal Article Optics and Photonics News · December 2005 Cite

Virial theorem and universality in a unitary fermi gas.

Journal Article Physical review letters · September 2005 Unitary Fermi gases, where the scattering length is large compared to the interparticle spacing, can have universal properties, which are independent of the details of the interparticle interactions when the range of the scattering potential is negligible. ... Full text Cite

Observation of phase conjugation of light arising from enhanced backscattering in a random medium.

Journal Article Physical review letters · September 2005 We measure the fundamental phase conjugation of a light field arising from enhanced backscattering in a multiple scattering medium. The measurements employ a two-window, time-resolved heterodyne method to suppress specularly reflected light and to determin ... Full text Cite

Observation of phase-sensitive temporal correlations in the resonance fluorescence from two-level atoms.

Journal Article Optics letters · September 2005 We have made what we believe is the first observation of phase-dependent temporal correlations in the fluorescent field emitted by coherently driven two-level atoms in free space. We measured the temporal fluctuations of the fluorescent field when the reso ... Full text Cite

Damping of a unitary Fermi gas.

Journal Article Physical review letters · May 2005 We measure the temperature dependence of the radial breathing mode in an optically trapped, unitary Fermi gas of 6Li, just above the center of a broad Feshbach resonance. The damping rate reveals a clear change in behavior which we interpret as arising fro ... Full text Cite

Heat capacity of a strongly interacting Fermi gas.

Journal Article Science (New York, N.Y.) · February 2005 We have measured the heat capacity of an optically trapped, strongly interacting Fermi gas of atoms. A precise addition of energy to the gas is followed by single-parameter thermometry, which determines the empirical temperature parameter of the gas cloud. ... Full text Cite

Breakdown of hydrodynamics in the radial breathing mode of a strongly interacting Fermi gas

Journal Article Physical Review A - Atomic, Molecular, and Optical Physics · November 1, 2004 The magnetic-field dependence of the frequency and damping time for the radial breathing mode of an optically trapped Fermi gas of 6Li atoms near a Feshbach resonance was investigated. For fields near 1080 G, a breakdown of hydrodynamic behavior was observ ... Full text Cite

Evidence for superfluidity in a resonantly interacting Fermi gas.

Journal Article Physical review letters · April 2004 We observe collective oscillations of a trapped, degenerate Fermi gas of 6Li atoms at a magnetic field just above a Feshbach resonance, where the two-body physics does not support a bound state. The gas exhibits a radial breathing mode at a frequency of 28 ... Full text Cite

Entanglement with classical fields

Journal Article Physical Review A - Atomic, Molecular, and Optical Physics · January 1, 2004 A simple classical-field optical heterodyne method which employs postselection to reproduce the polarization correlations of four-particle entangled state was experimentally analyzed. A heuristic argument relating this method to the measurement of multiple ... Full text Cite

Optically Trapped Fermi Gases

Journal Article American Scientist · 2004 Full text Cite

Mechanical stability of a strongly interacting Fermi gas of atoms

Journal Article Physical Review A - Atomic, Molecular, and Optical Physics · January 1, 2003 A strongly attractive, two-component Fermi gas of atoms exhibits universal behavior and should be mechanically stable as a consequence of the quantum-mechanical requirement of unitarity. This requirement limits the maximum attractive force to a value small ... Full text Cite

Unitarity-limited elastic collision rate in a harmonically trapped Fermi gas

Journal Article Physical Review A - Atomic, Molecular, and Optical Physics · January 1, 2003 We derive the elastic collision rate for a harmonically trapped Fermi gas in the extreme unitarity limit where the s-wave scattering cross section is [Formula Presented] with [Formula Presented] the relative momentum. The collision rate is given in the for ... Full text Cite

Dynamics of a highly-degenerate, strongly-interacting Fermi gas of atoms

Journal Article Journal of Low Temperature Physics · 2003 Cite

Observation of a strongly interacting degenerate Fermi gas of atoms.

Journal Article Science (New York, N.Y.) · December 2002 We report on the observation of a highly degenerate, strongly interacting Fermi gas of atoms. Fermionic lithium-6 atoms in an optical trap are evaporatively cooled to degeneracy using a magnetic field to induce strong, resonant interactions. Upon abruptly ... Full text Cite

All-optical production of a degenerate Fermi gas.

Journal Article Physical review letters · March 2002 We achieve degeneracy in a mixture of the two lowest hyperfine states of 6Li by direct evaporation in a CO2 laser trap, yielding the first all optically produced degenerate Fermi gas. More than 10(5) atoms are confined at temperatures below 4 microK at ful ... Full text Cite

Experimental simulation of two-particle quantum entanglement using classical fields.

Journal Article Physical review letters · March 2002 We experimentally demonstrate simulation of two entangled quantum bits using classical fields of two frequencies and two polarizations. Multiplication of optical heterodyne beat signals from two spatially separated regions simulates coincidence detection o ... Full text Cite

Measurement of the zero crossing in a Feshbach resonance of fermionic [Formula Presented]

Journal Article Physical Review A - Atomic, Molecular, and Optical Physics · January 1, 2002 We measure a zero crossing in the scattering length of a mixture of the two lowest hyperfine states of [Formula Presented] To locate the zero crossing, we monitor the decrease in temperature and atom number arising from evaporation in a [Formula Presented] ... Full text Cite

Standing room only at the quantum scale

Journal Article Science · 2001 Cite

Loading Dynamics of CO2 Laser Traps

Journal Article Phys. Rev. A · 2001 Cite

Stable, strongly attractive, two-state mixture of lithium fermions in an optical trap

Journal Article Physical review letters · September 2000 We use an all-optical trap to confine a strongly attractive two-state mixture of lithium fermions. By measuring the rate of evaporation from the trap, we determine the effective elastic scattering cross section 4pia(2) to show that the magnitude of the sca ... Full text Cite

Heterodyne measurement of Wigner distributions for classical optical fields.

Journal Article Optics letters · October 1999 We demonstrate a two-window heterodyne method for measuring the x-p cross correlation, ??(*)(x)? (p)?, of an optical field ? for transverse position x and transverse momentum p. This scheme permits independent control of the x and p resolution. A simple li ... Full text Cite

Optical phase-space distributions for low-coherence light.

Journal Article Optics letters · September 1999 Using a novel heterodyne technique, we measure optical phase-space distributions in momentum and position for low-coherence light. Quantitative information is obtained simultaneously about the longitudinal and the transverse coherence properties as well as ... Full text Cite

Ultrastable CO2laser trapping of lithium fermions

Journal Article Physical Review Letters · January 1, 1999 We demonstrate an ultrastable CO2laser trap that provides tight confinement of neutral atoms with negligible optical scattering and minimal laser-noise-induced heating. Using this method, fermionic6Li atoms are stored in a 0.4 mK deep well with a 1/e trap ... Full text Cite

Noise induced Population Loss in Atom Traps

Journal Article Bull. Am. Phys. Soc. · 1999 Cite

Observation of squeezing in the phase-dependent fluorescence spectra of two-level atoms

Journal Article Physical Review Letters · October 26, 1998 We observe squeezing in the phase-dependent fluorescence spectra of two-level atoms that are coherently driven by a near-resonant laser field in free space. In contrast to previous predictions that emphasized the in- and out-of-phase quadratures, we find t ... Full text Cite

Measurement of smoothed Wigner phase-space distributions for small-angle scattering in a turbid medium.

Journal Article Journal of the Optical Society of America. A, Optics, image science, and vision · July 1998 We study Wigner phase-space distributions W (x, p) in position (x) and momentum (p) for light undergoing multiple small-angle scattering in a turbid medium. Smoothed Wigner phase-space distributions are measured by using a heterodyne technique that achieve ... Full text Cite

Dynamics of Noise-Induced Heating in Atom Traps

Journal Article Phys. Rev. A · 1998 Cite

Raman Induced Magnetic Resonance Imaging of Atoms in a MOT

Journal Article Bull. Am. Phys. Soc. · 1998 Cite