ALBERT

Description: Author(s): Y. A. Liao, M. Revelle, T. Paprotta, A. S. C. Rittner, Wenhui Li, G. B. Partridge, and R. G. Hulet We study the role of particle transport and evaporation on the phase separation of an ultracold, spin-polarized atomic Fermi gas. We show that the previously observed deformation of the superfluid paired core is a result of evaporative depolarization of the superfluid due to a combination of enhance... [Phys. Rev. Lett. 107, 145305] Published Wed Sep 28, 2011

Description: Author(s): P. M. Duarte, R. A. Hart, J. M. Hitchcock, T. A. Corcovilos, T.-L. Yang, A. Reed, and R. G. Hulet [Phys. Rev. A 84, 061406] Published Wed Dec 21, 2011

Description: We report the attainment of simultaneous quantum degeneracy in a mixed gas of bosons (lithium-7) and fermions (lithium-6). The Fermi gas has been cooled to a temperature of 0.25 times the Fermi temperature by thermal collisions with the evaporatively cooled bosons. At this temperature, the spatial size of the gas is strongly affected by the Fermi pressure resulting from the Pauli exclusion principle and gives clear experimental evidence for quantum degeneracy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Truscott, A G -- Strecker, K E -- McAlexander, W I -- Partridge, G B -- Hulet, R G -- New York, N.Y. -- Science. 2001 Mar 30;291(5513):2570-2. Epub 2001 Mar 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy and the Rice Quantum Institute, Rice University, Houston, TX 77251, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11283362" target="_blank"〉PubMed〈/a〉

Description: Superconductivity and magnetism generally do not coexist. Changing the relative number of up and down spin electrons disrupts the basic mechanism of superconductivity, where atoms of opposite momentum and spin form Cooper pairs. Nearly forty years ago Fulde and Ferrell and Larkin and Ovchinnikov (FFLO) proposed an exotic pairing mechanism in which magnetism is accommodated by the formation of pairs with finite momentum. Despite intense theoretical and experimental efforts, however, polarized superconductivity remains largely elusive. Unlike the three-dimensional (3D) case, theories predict that in one dimension (1D) a state with FFLO correlations occupies a major part of the phase diagram. Here we report experimental measurements of density profiles of a two-spin mixture of ultracold (6)Li atoms trapped in an array of 1D tubes (a system analogous to electrons in 1D wires). At finite spin imbalance, the system phase separates with an inverted phase profile, as compared to the 3D case. In 1D, we find a partially polarized core surrounded by wings which, depending on the degree of polarization, are composed of either a completely paired or a fully polarized Fermi gas. Our work paves the way to direct observation and characterization of FFLO pairing.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liao, Yean-An -- Rittner, Ann Sophie C -- Paprotta, Tobias -- Li, Wenhui -- Partridge, Guthrie B -- Hulet, Randall G -- Baur, Stefan K -- Mueller, Erich J -- England -- Nature. 2010 Sep 30;467(7315):567-9. doi: 10.1038/nature09393.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77251, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20882011" target="_blank"〉PubMed〈/a〉

Description: Author(s): T. L. Yang, P. Grišins, Y. T. Chang, Z. H. Zhao, C. Y. Shih, T. Giamarchi, and R. G. Hulet Bragg spectroscopy on a one-dimensional interacting Fermi gas reveals a dynamic response in good agreement with Tomonaga-Luttinger liquid theory. [Phys. Rev. Lett. 121, 103001] Published Tue Sep 04, 2018

Description: Under certain circumstances, three or more interacting particles may form bound states. Although the general few-body problem is not analytically solvable, the so-called Efimov trimers appear for a system of three particles with resonant two-body interactions. The binding energies of these trimers are predicted to be universally connected to each other, independent of the microscopic details of the interaction. By exploiting a Feshbach resonance to widely tune the interactions between trapped ultracold lithium atoms, we find evidence for two universally connected Efimov trimers and their associated four-body bound states. A total of 11 precisely determined three- and four-body features are found in the inelastic-loss spectrum. Their relative locations on either side of the resonance agree well with universal theory, whereas a systematic deviation from universality is found when comparing features across the resonance.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pollack, Scott E -- Dries, Daniel -- Hulet, Randall G -- New York, N.Y. -- Science. 2009 Dec 18;326(5960):1683-5. doi: 10.1126/science.1182840. Epub 2009 Nov 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, TX 77005, USA. scott.pollack@rice.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19965389" target="_blank"〉PubMed〈/a〉

Description: We report the observation of pairing in a gas of atomic fermions with unequal numbers of two components. Beyond a critical polarization, the gas separates into a phase that is consistent with a superfluid paired core surrounded by a shell of normal unpaired fermions. The critical polarization diminishes with decreasing attractive interaction. For near-zero polarization, we measured the parameter beta = -0.54 +/- 0.05, describing the universal energy of a strongly interacting paired Fermi gas, and found good agreement with recent theory. These results are relevant to predictions of exotic new phases of quark matter and of strongly magnetized superconductors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Partridge, Guthrie B -- Li, Wenhui -- Kamar, Ramsey I -- Liao, Yean-An -- Hulet, Randall G -- New York, N.Y. -- Science. 2006 Jan 27;311(5760):503-5. Epub 2005 Dec 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, TX 77251, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16373534" target="_blank"〉PubMed〈/a〉

Description: Ultracold atoms in optical lattices have great potential to contribute to a better understanding of some of the most important issues in many-body physics, such as high-temperature superconductivity. The Hubbard model--a simplified representation of fermions moving on a periodic lattice--is thought to describe the essential details of copper oxide superconductivity. This model describes many of the features shared by the copper oxides, including an interaction-driven Mott insulating state and an antiferromagnetic (AFM) state. Optical lattices filled with a two-spin-component Fermi gas of ultracold atoms can faithfully realize the Hubbard model with readily tunable parameters, and thus provide a platform for the systematic exploration of its phase diagram. Realization of strongly correlated phases, however, has been hindered by the need to cool the atoms to temperatures as low as the magnetic exchange energy, and also by the lack of reliable thermometry. Here we demonstrate spin-sensitive Bragg scattering of light to measure AFM spin correlations in a realization of the three-dimensional Hubbard model at temperatures down to 1.4 times that of the AFM phase transition. This temperature regime is beyond the range of validity of a simple high-temperature series expansion, which brings our experiment close to the limit of the capabilities of current numerical techniques, particularly at metallic densities. We reach these low temperatures using a compensated optical lattice technique, in which the confinement of each lattice beam is compensated by a blue-detuned laser beam. The temperature of the atoms in the lattice is deduced by comparing the light scattering to determinant quantum Monte Carlo simulations and numerical linked-cluster expansion calculations. Further refinement of the compensated lattice may produce even lower temperatures which, along with light scattering thermometry, would open avenues for producing and characterizing other novel quantum states of matter, such as the pseudogap regime and correlated metallic states of the two-dimensional Hubbard model.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hart, Russell A -- Duarte, Pedro M -- Yang, Tsung-Lin -- Liu, Xinxing -- Paiva, Thereza -- Khatami, Ehsan -- Scalettar, Richard T -- Trivedi, Nandini -- Huse, David A -- Hulet, Randall G -- England -- Nature. 2015 Mar 12;519(7542):211-4. doi: 10.1038/nature14223. Epub 2015 Feb 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy and Rice Quantum Institute, Rice University, 6100 Main Street, Houston, Texas 77005, USA. ; Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68.528, Rio de Janeiro RJ, 21941-972, Brazil. ; Department of Physics and Astronomy, San Jose State University, 1 Washington Square, San Jose, California 95192, USA. ; Department of Physics, University of California, 1 Shields Avenue, Davis, California 95616, USA. ; Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210, USA. ; Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25707803" target="_blank"〉PubMed〈/a〉

Description: Author(s): P. Dyke, S. E. Pollack, and R. G. Hulet We have measured the binding energy of 7 Li Feshbach molecules deep into the nonuniversal regime by associating atoms in a Bose-Einstein condensate with a modulated magnetic field. We extract the scattering length from these measurements, correcting for nonuniversal short-range effects using the fiel... [Phys. Rev. A 88, 023625] Published Fri Aug 30, 2013