Bulletin of the American Physical Society
41st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 55, Number 5
Tuesday–Saturday, May 25–29, 2010; Houston, Texas
Session W6: Strongly Interacting Fermi Gases II |
Hide Abstracts |
Chair: Thomas Killian, Rice University Room: Arboretum IV-V |
Saturday, May 29, 2010 8:00AM - 8:12AM |
W6.00001: Equation of State of a Strongly Interacting Atomic Fermi Gas Mark Ku, Andre Schirotzek, Ariel Sommer, Martin Zwierlein, Kris Van Houcke, Felix Werner, Evgeny Kozik, Nikolay Prokofev, Boris Svistunov We study the equation of state of a Fermi gas with unitarity limited interactions by in-situ imaging of ultracold $^6$Li at a Feshbach resonance. The low noise density distribution in an external potential directly probes the equation of state under the local density approximation. The equation of state is obtained in two ways: from the local density of the gas, reconstructed using the inverse Abel transformation; and from the local pressure, directly deduced from the 2D column density via an exact relation including the Gaussian potential. Regions of low density allow us to extract the chemical potential and the temperature using the virial expansion of the equation of state. We validate our method using the non-interacting Fermi gas. The experimental results are compared to recent Monte-Carlo calculations. [Preview Abstract] |
Saturday, May 29, 2010 8:12AM - 8:24AM |
W6.00002: Repulsively Interacting Two-Component Fermi Gases: a Quantum Monte Carlo Study Sebastiano Pilati, Gianluca Bertaina, Stefano Giorgini, Matthias Troyer We study the ground-state properties of a two-component Fermi gas with repulsive inter-species interactions using quantum Monte Carlo techniques. We calculate the equation of state as a function of the interaction parameter and of the population imbalance. We determine the critical interaction strength where the two components separate forming polarized domains and a ferromagnetic state appears. [Preview Abstract] |
Saturday, May 29, 2010 8:24AM - 8:36AM |
W6.00003: Cold fermions at unitarity: variations on a theme Alexandros Gezerlis, Aurel Bulgac, J. Carlson Quantum Monte Carlo calculations for superfluid two-species homogeneous fermionic systems at unitarity already have a history of at least half a decade. In this talk, we will describe newer zero-temperature Diffusion Monte Carlo results for the equation of state and the pairing gap, as well as for other properties such as the excitation spectrum and distribution functions. Our physical systems of interest will be, on the one hand, a heavy-light system with a mass ratio corresponding to a $^6$Li-$^{40}$K mixture, and, on the other, a three-species gas of $^6$Li. [Preview Abstract] |
Saturday, May 29, 2010 8:36AM - 8:48AM |
W6.00004: The Equation of State of a Strongly Interacting Fermi Gas Nir Navon, Sylvain Nascimb\`ene, Kaijun Jiang, Fr\'ed\'eric Chevy, Christophe Salomon In this talk, we will present recent experimental work on the thermodynamics of strongly interacting Fermi gases. We have developed a general method to probe with high precision the Equation of State (EoS) of locally homogeneous ultracold gases [1]. This allows stringent tests of recent many-body theories. First, we focus on the finite-temperature EoS of the unpolarized unitary gas. Precise thermometry is provided by adding to the Fermi gas of $^{6}$Li a trace of bosonic $^{7}$Li. We show that the low-temperature properties of the strongly interacting normal phase are well described by Fermi liquid theory and we localize the superfluid transition. Second, we address the zero-temperature EoS of the spin-polarized system. Surprisingly, despite strong interactions, the polarized phase behaves as a mixture of two ideal gases: a Fermi gas of majority atoms and a non-interacting gas of dressed quasi-particles, the Fermi polarons. Finally, we will report on work in progress on the extension of our study to the BEC-BCS crossover [2]. \\[4pt] [1] S. Nascimbene and N. Navon, K. Jiang, F. Chevy, C. Salomon, arXiv:0911.0747, Nature (in press, 2010) \\[0pt] [2] N. Navon and S. Nascimbene, F. Chevy, C. Salomon, in preparation (2010) [Preview Abstract] |
Saturday, May 29, 2010 8:48AM - 9:00AM |
W6.00005: The Role of the Contact in the rf Spectroscopy of a Strongly-interacting Fermi Gas Eric Braaten, Daekyoung Kang, Lucas Platter Universal relations that hold for any state provide powerful constraints on systems consisting of fermions with two spin states interacting with a large scattering length. In radio-frequency (rf) spectroscopy, the mean shift in the rf frequency and the large frequency tail of the rf transition rate are proportional to the contact, which measures the density of pairs with small separations. We show that these universal relations can be derived and extended by using the short-time operator product expansion of quantum field theory. This is a general method for identifing aspects of many-body physics that are controlled by few-body physics. [Preview Abstract] |
Saturday, May 29, 2010 9:00AM - 9:12AM |
W6.00006: Is it possible to access the strongly interacting regime with a $^6$Li$^{40}$K Fermi-Fermi mixture? Andreas Trenkwalder, Christoph Kohstall, Frederik Spiegelhalder, Devang Naik, Gerhard Hendl, Florian Schreck, Rudolf Grimm Interspecies Feshbach resonances in the $^6$Li$^{40}$K Fermi-Fermi mixture are closed-channel dominated and quite narrow. With the goal to realize a strongly interacting mixture we have measured the elastic and inelastic scattering properties across one of the widest interspecies resonances available in this system. Our results identify the narrow magnetic field range where the scattering length exceeds the interparticle spacing. We report on our first experimental steps exploring this strongly interacting regime. [Preview Abstract] |
Saturday, May 29, 2010 9:12AM - 9:24AM |
W6.00007: Strongly Interacting Fermi and Bose-Fermi Gases Ye-ryoung Lee, Jae Choi, Caleb Christensen, Gyu-boong Jo, Tout Wang, Wolfgang Ketterle, David Pritchard We present our recent progress on the study ultracold gases of $^{6}$Li and $^{23}$Na near homonuclear and heteronuclear Feshbach resonances. We discuss new experimental and theoretical developments on itinerant ferromagnetism in a Fermi gas of ultracold atoms [1]. We also report on ultracold gases of $^{6}$Li and $^{23}$Na, including fermionic LiNa molecules. \\[4pt] [1] G.-B. Jo, Y.-R. Lee, J.-H. Choi, C.A. Christensen, T.H. Kim, J.H. Thywissen, D.E. Pritchard, and W. Ketterle, Observation of itinerant ferromagnetism in a strongly interacting Fermi gas of ultracold atoms, Science 325, 1521 (2009). [Preview Abstract] |
Saturday, May 29, 2010 9:24AM - 9:36AM |
W6.00008: Investigation of the 3D to 1D Crossover of a Spin-Imbalanced Fermi Gas Tobias Paprotta, Yean-An Liao, Ann Sophie C. Rittner, Randall G. Hulet Spin-imbalanced Fermi gases have been investigated in 3D geometries, for which phase separation into normal and superfluid phases has been observed\footnote{G. B. Partridge et al., Science 311, 503-505 (2006); C.H. Schunck et al., Science 316, 867-870 (2007).}. More recently, we have mapped the phase diagram for the 1D gas, by confining the system to a 2D optical lattice, which creates an array of tubes\footnote{Y.A. Liao et al., arxiv:0912.0092}. In 1D, the spatial positions of the superfluid and normal gas are inverted, with the unpolarized superfluid occupying the trap edge, rather than the center. We investigate this dimensional crossover by tuning the depth of the lattice, which smoothly modifies the inter-tube tunneling. For sufficiently large tunneling rates, the system is effectively 3D. Spin transport velocities obtained from this study will allow better estimates of equilibration times in many types of optical lattice experiments. [Preview Abstract] |
Saturday, May 29, 2010 9:36AM - 9:48AM |
W6.00009: Strongly interacting two-dimensional Dirac fermions Lih-King Lim, Achilleas Lazarides, Andreas Hemmerich, C. Morais Smith We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time-reversal and inversion symmetries [1]. We find remarkable phenomena in a temperature range around a tenth of the Fermi-temperature, accessible with present experimental techniques: at zero chemical potential, besides a conventional $s$-wave superconducting phase, unconventional superconductivity with non-local bond pairing arises. In a temperature versus doping phase diagram, the unconventional superconducting phase exhibits a dome structure, reminiscent of the phase diagram for high-temperature superconductors and heavy fermions [2]. \\[4pt] [1] Lih-King Lim, C. Morais Smith, and Andreas Hemmerich, PRL 100, 130402 (2008).\\[0pt] [2] Lih-King Lim, Achilleas Lazarides, Andreas Hemmerich, and C. Morais Smith, EPL 88, 36001 (2009). [Preview Abstract] |
Saturday, May 29, 2010 9:48AM - 10:00AM |
W6.00010: Single impurity in cold Fermi superfluids Lei Jiang, Han Pu Single impurity will change local properties in ultracold Fermi superfluids. Spatially resolved radio frequency spectroscopy gives us a tool to detect local properties of ultracold Fermions and hence can be used to investigate the effects of impurities. Here we calculate the radio frequency spectrum using the T-matrix formalism with single impurity. This impurity can be either potential scattering or scattering with other atoms; either magnetic or non-magnetic. We find single impurity can be used as a probe to detect Fermi pairing in radio frequency spectrum in population balanced system. It can be used to detect whether the system is in BEC region or in BCS region. We compare magnetic impurity spectra with non-magnetic ones. We also discuss the appearance of bound states near the impurity site. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700