A5036833971- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Advanced Frequency and Time Standards
- Quantum Mechanics and Applications
- Quantum Information and Cryptography
- Quantum, superfluid, helium dynamics
- Quantum optics and atomic interactions
- Experimental and Theoretical Physics Studies
- Mechanical and Optical Resonators
- Quantum Computing Algorithms and Architecture
- Strong Light-Matter Interactions
- Atomic and Molecular Physics
- Advanced Thermodynamics and Statistical Mechanics
- Scientific Measurement and Uncertainty Evaluation
- Photonic and Optical Devices
- Advanced Measurement and Metrology Techniques
- Geophysics and Sensor Technology
- Quantum Electrodynamics and Casimir Effect
- Spectroscopy and Laser Applications
- Optical properties and cooling technologies in crystalline materials
- Inorganic Fluorides and Related Compounds
- Characterization and Applications of Magnetic Nanoparticles
- Advanced Electrical Measurement Techniques
- Advanced Fiber Optic Sensors
- Advanced MEMS and NEMS Technologies
University of Virginia
2015-2025
McCormick (United States)
2016-2017
United States University
2015
National Institute of Standards and Technology
1993-2008
University of Colorado Boulder
1993-2008
Joint Institute for Laboratory Astrophysics
1993-2008
Rice University
1995-2002
Macquarie University
2002
Evidence for Bose-Einstein condensation of a gas spin-polarized ${}^{7}$Li atoms is reported. Atoms confined to permanent-magnet trap are laser cooled 200 \ensuremath{\mu}K and then evaporatively lower temperatures. Phase-space densities consistent with quantum degeneracy measured temperatures in the range 100 400 nK. At these high phase-space densities, diffraction probe beam observed. Modeling shows that this sensitive indicator presence spatially localized condensate. Although...
Bose-Einstein condensation of ${}^{7}\mathrm{Li}$ has been studied in a magnetically trapped gas. Because the effectively attractive interactions between atoms, many-body quantum theory predicts that occupation number condensate is limited to about 1400 atoms. We observe be maximum value 650 and 1300 The measurements were made using versatile phase-contrast imaging technique.
We have investigated motional heating of laser-cooled ${}^{9}{\mathrm{Be}}^{+}$ ions held in radio-frequency (Paul) traps. measured rates a variety traps with different geometries, electrode materials, and characteristic sizes. The results show that is due to electric-field noise from the trap electrodes exerts stochastic fluctuating force on ion. scaling rate size much stronger than expected spatially uniform source (such as Johnson external circuits), indicating microscopic uncorrelated...
We demonstrate a decoherence-free quantum memory of one qubit. By encoding the qubit into subspace (DFS) pair trapped 9Be+ ions, we protect from environment-induced dephasing that limits storage time composed single ion. measured under ambient conditions and interaction with an engineered noisy environment observed DFS increases by up to order magnitude. The reversibly transfers arbitrary stored in ion two ions.
We study the prospects for observing superfluidity in a spin-polarized atomic gas of $^6$Li atoms, using state-of-the-art interatomic potentials. determine spinodal line and show that BCS transition to superfluid state can indeed occur (meta)stable region phase diagram if densities are sufficiently low. Moreover, total density $10^{12}~cm^{-3}$, which still fulfills this requirement, we find critical temperature only $29~nK$. also discuss stability due exchange dipolar relaxation conclude...
We experimentally investigate three methods, utilizing different atomic observables and entangled states, to increase the sensitivity of rotation angle measurements beyond "standard quantum limit" for nonentangled states. All methods use a form mechanical "squeezing." In system two trapped (9)Be(+) ions we observe reduction in uncertainty below standard limit all including sources noise. As an application, demonstrate precision frequency measurement Ramsey spectroscopy experiment.
We present results from an experimental study of the decoherence and decay quantum states a trapped atomic ion's harmonic motion interacting with several types engineered reservoirs. experimentally simulate three reservoirs: high-temperature amplitude reservoir, zero-temperature phase reservoir. Interaction these environments causes motional state to or heat, in case superposition states, lose coherence. report measurements superpositions coherent two-Fock-state into reservoirs, as well...
We have measured the elastic collision cross section for spin polarized atomic cesium. Neutral cesium atoms are optically cooled, then loaded into a dc magnetic trap. infer scattering rate from at which anisotropies in initial energy distribution observed to relax. The F=3, ${\mathit{m}}_{\mathit{F}}$=-3 on is 1.5(4)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}12}$ ${\mathrm{cm}}^{2}$, and independent of temperature 30 250 \ensuremath{\mu}K. This determination clarifies...
Two-photon photoassociation of colliding ultracold ${}^{7}$Li atoms is used to probe the $^{3}\ensuremath{\Sigma}_{u}^{+}(a)$ ground state ${}^{7}$L${\mathrm{i}}_{2}$. The binding energy least-bound this triplet potential, $\ensuremath{\upsilon}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}10$, found be $12.47\ifmmode\pm\else\textpm\fi{}0.04$ GHz. This spectroscopic information establishes that $s$-wave scattering length for in $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$,...
We report on a study of the superfluid state spin-polarized atomic Li6 confined in magnetic trap. Density profiles this degenerate Fermi gas, and spatial distribution BCS order parameter are calculated local density approximation. The critical temperature is determined as function number particles Furthermore we consider mechanical stability an interacting two-component both case attractive repulsive interatomic interactions. For also calculate decay rate show that within mechanically stable...
We describe a Sagnac interferometer suitable for rotation sensing, implemented using an atomic Bose-Einstein condensate confined in harmonic magnetic trap. The atom wave packets are split and recombined by standing-wave Bragg lasers, the trapping potential steers along circular trajectories with radius of 0.2 mm. Two conjugate interferometers simultaneously to provide common-mode rejection noise isolate signal. With interference visibilities about 50%, we achieve sensitivity comparable...
Deployment of ultracold atom interferometers (AI) into space will capitalize on quantum advantages and the extended freefall persistent microgravity to provide high-precision measurement capabilities for gravitational, Earth, planetary sciences, enable searches subtle forces signifying physics beyond General Relativity Standard Model. NASA's Cold Atom Lab (CAL) operates onboard International Space Station as a multi-user facility fundamental studies atoms mature space-based technologies. We...
The occupation number of a magnetically trapped Bose-Einstein condensate is limited for atoms with attractive interactions. It has been predicted that, as this limit approached, the will collapse by collective process. measured spread in samples ${}^{7}\mathrm{Li}$ undergoing thermal equilibration consistent occurrence such collapses.
We consider the dynamics of a quantum degenerate trapped gas Li-7 atoms. Because atoms have negative s-wave scattering length, Bose condensate becomes mechanically unstable when number approaches maximum value. calculate collapse that occurs point is reached. In addition, we use Boltzmann equation to investigate nonequilibrium kinetics atomic distribution during and after evaporative cooling. The found undergo many cycles growth before stationary state
One limit to the fidelity of quantum logic operations on trapped ions arises from heating ions' collective modes motion. Sympathetic cooling during may eliminate this source errors. We discuss benefits and drawbacks proposal, describe possible experimental implementations. also present an overview trapped-ion dynamics in scheme.
The loading dynamics of an alkali-metal-atom magneto-optical trap can be used as a reliable measure vacuum pressure, with time $\ensuremath{\tau}$ indicating pressure less than or equal to ($2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ Torr s)/$\ensuremath{\tau}$. This relation is accurate approximately factor 2 over wide variations in parameters, background gas composition, trapped alkali-metal species. low-pressure limit the method does depend on but typically extends below...
A Michelson interferometer using Bose-Einstein condensates is demonstrated with coherence times of up to $44\phantom{\rule{0.3em}{0ex}}\mathrm{ms}$ and arm separations $180\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{m}$. This separation larger than that observed for any previous atom interferometer. The device uses atoms weakly confined in a magnetic guide the atomic motion controlled Bragg interactions an off-resonant standing-wave laser beam.
We report an experimental measurement of a light wavelength at which the ac electric polarizability equals zero for 87Rb atoms in F=2 ground hyperfine state. The experiment uses condensate interferometer both to find this 'tune-out' and accurately determine polarization it. lies between D1 D2 spectral lines 790.03235(3) nm. is sensitive tensor contribution polarizability, has been removed so that reported value scalar polarizability. precision fifty times better than previous tune-out...