@article{jagannathan_arunkumar_joseph_thomas_2016, title={Optical Control of Magnetic Feshbach Resonances by Closed-Channel Electromagnetically Induced Transparency}, volume={116}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.116.075301}, abstractNote={We control magnetic Feshbach resonances in an optically trapped mixture of the two lowest hyperfine states of a ^{6}Li Fermi gas, using two optical fields to create a dark state in the closed molecular channel. In the experiments, the narrow Feshbach resonance is tuned by up to 3 G. For the broad resonance, the spontaneous lifetime is increased to 0.4 s at the dark-state resonance, compared to 0.5 ms for single-field tuning. We present a new model of light-induced loss spectra, employing continuum-dressed basis states, which agrees in shape and magnitude with loss measurements for both broad and narrow resonances. Using this model, we predict the trade-off between tunability and loss for the broad resonance in ^{6}Li, showing that our two-field method substantially reduces the two-body loss rate compared to single-field methods for the same tuning range.}, number={7}, journal={PHYSICAL REVIEW LETTERS}, author={Jagannathan, A. and Arunkumar, N. and Joseph, J. A. and Thomas, J. E.}, year={2016}, month={Feb} }
 @article{joseph_elliott_thomas_2015, title={Shear Viscosity of a Unitary Fermi Gas Near the Superfluid Phase Transition}, volume={115}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.115.020401}, abstractNote={We measure the shear viscosity for a resonantly interacting Fermi gas as a function of temperature from nearly the ground state through the superfluid phase transition into the high temperature regime. Further, we demonstrate an iterative method to estimate the local shear viscosity coefficient α(S)(θ) versus reduced temperature θ from the cloud-averaged measurements ⟨α(S)⟩, and compare α(S) to several microscopic theories. We find that α(S) reveals features that were previously hidden in ⟨α(S)⟩.}, number={2}, journal={PHYSICAL REVIEW LETTERS}, author={Joseph, J. A. and Elliott, E. and Thomas, J. E.}, year={2015}, month={Jul} }
 @article{elliott_joseph_thomas_2014, title={Anomalous Minimum in the Shear Viscosity of a Fermi Gas}, volume={113}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.113.020406}, abstractNote={We measure the static shear viscosity η in a two-component Fermi gas near a broad collisional (Feshbach) resonance, as a function of interaction strength and energy. We find that η has both a quadratic and a linear dependence on the interaction strength 1/(k(FI)a), where a is the s-wave scattering length and k(FI) is the Fermi wave vector for an ideal gas at the trap center. For energies above the superfluid transition, the minimum in η as a function of interaction strength is significantly shifted toward the BEC side of resonance, to 1/(k(FI)a)≃0.25.}, number={2}, journal={PHYSICAL REVIEW LETTERS}, author={Elliott, E. and Joseph, J. A. and Thomas, J. E.}, year={2014}, month={Jul} }
 @article{elliott_joseph_thomas_2014, title={Observation of Conformal Symmetry Breaking and Scale Invariance in Expanding Fermi Gases}, volume={112}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.112.040405}, abstractNote={We precisely test scale invariance and examine local thermal equilibrium in the hydrodynamic expansion of a Fermi gas of atoms as a function of interaction strength. After release from an anisotropic optical trap, we observe that a resonantly interacting gas obeys scale-invariant hydrodynamics, where the mean square cloud size = expands ballistically (like a noninteracting gas) and the energy-averaged bulk viscosity is consistent with zero, 0.00(0.04)ℏn, with n the density. In contrast, the aspect ratios of the cloud exhibit anisotropic "elliptic" flow with an energy-dependent shear viscosity. Tuning away from resonance, we observe conformal symmetry breaking, where deviates from ballistic flow.}, number={4}, journal={PHYSICAL REVIEW LETTERS}, author={Elliott, E. and Joseph, J. A. and Thomas, J. E.}, year={2014}, month={Jan} }