@article{huang_royse_arakelyan_thomas_2023, title={Verifying a quasiclassical spin model of perturbed quantum rewinding in a Fermi gas}, volume={108}, ISSN={["2469-9934"]}, url={https://doi.org/10.1103/PhysRevA.108.L041304}, DOI={10.1103/PhysRevA.108.L041304}, abstractNote={We systematically test a quasi-classical spin model of a large spin-lattice in energy space, with a tunable, reversible Hamiltonian and effective long-range interactions. The system is simulated by a weakly interacting Fermi gas undergoing perturbed quantum rewinding using radio-frequency(RF) pulses. The model reported here is found to be in a quantitative agreement with measurements of the ensemble-averaged energy-resolved spin density. This work elucidates the effects of RF detunings on the system and measurements, pointing the way to new correlation measurement methods.}, number={4}, journal={PHYSICAL REVIEW A}, author={Huang, J. and Royse, Camen A. and Arakelyan, I. and Thomas, J. E.}, year={2023}, month={Oct} }
@article{wang_li_arakelyan_thomas_2022, title={Hydrodynamic Relaxation in a Strongly Interacting Fermi Gas}, volume={128}, ISSN={["1079-7114"]}, url={https://doi.org/10.1103/PhysRevLett.128.090402}, DOI={10.1103/PhysRevLett.128.090402}, abstractNote={We measure the free decay of a spatially periodic density profile in a normal fluid strongly interacting Fermi gas, which is confined in a box potential. This spatial profile is initially created in thermal equilibrium by a perturbing potential. After the perturbation is abruptly extinguished, the dominant spatial Fourier component exhibits an exponentially decaying (thermally diffusive) mode and a decaying oscillatory (first sound) mode, enabling independent measurement of the thermal conductivity and the shear viscosity directly from the time-dependent evolution.}, number={9}, journal={PHYSICAL REVIEW LETTERS}, author={Wang, Xin and Li, Xiang and Arakelyan, Ilya and Thomas, J. E.}, year={2022}, month={Mar} }
@article{pegahan_arakelyan_thomas_2021, title={Energy-Resolved Information Scrambling in Energy-Space Lattices}, volume={126}, ISSN={["1079-7114"]}, url={https://doi.org/10.1103/PhysRevLett.126.070601}, DOI={10.1103/PhysRevLett.126.070601}, abstractNote={Weakly interacting Fermi gases simulate spin lattices in energy space, offering a rich platform for investigating information spreading and spin coherence in a large many-body quantum system. We show that the collective spin vector can be determined as a function of energy from the measured spin density, enabling general energy-space resolved protocols. We measure an out-of-time-order correlation function in this system and observe the energy dependence of the many-body coherence.}, number={7}, journal={PHYSICAL REVIEW LETTERS}, author={Pegahan, S. and Arakelyan, I and Thomas, J. E.}, year={2021}, month={Feb} }
@article{pegahan_kangara_arakelyan_thomas_2019, title={Spin-energy correlation in degenerate weakly interacting Fermi gases}, volume={99}, ISSN={["2469-9934"]}, DOI={10.1103/PhysRevA.99.063620}, abstractNote={Weakly interacting Fermi gases exhibit rich collective dynamics in spin-dependent potentials, arising from correlations between spin degrees of freedom and conserved single atom energies, offering broad prospects for simulating many-body quantum systems by engineering energy-space "lattices," with controlled energy landscapes and site to site interactions. Using quantum degenerate clouds of $^6$Li, confined in a spin-dependent harmonic potential, we measure complex, time-dependent spin-density profiles, varying on length scales much smaller than the cloud size. We show that a one-dimensional mean field model, without additional simplifying approximations, quantitatively predicts the observed fine structure. We measure the magnetic fields where the scattering lengths vanish for three different hyperfine state mixtures to provide new constraints on the collisional (Feshbach) resonance parameters.}, number={6}, journal={PHYSICAL REVIEW A}, author={Pegahan, S. and Kangara, J. and Arakelyan, I and Thomas, J. E.}, year={2019}, month={Jun} }
@article{kangara_cheng_pegahan_arakelyan_thomas_2018, title={Atom Pairing in Optical Superlattices}, volume={120}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.120.083203}, abstractNote={We study the pairing of fermions in a one-dimensional lattice of tunable double-well potentials using radio-frequency spectroscopy. The spectra reveal the coexistence of two types of atom pairs with different symmetries. Our measurements are in excellent quantitative agreement with a theoretical model, obtained by extending the Green's function method of Orso et al. [Phys. Rev. Lett. 95, 060402 (2005)PRLTAO0031-900710.1103/PhysRevLett.95.060402] to a bichromatic 1D lattice with nonzero harmonic radial confinement. The predicted spectra comprise hundreds of discrete transitions, with symmetry-dependent initial state populations and transition strengths. Our work provides an understanding of the elementary pairing states in a superlattice, paving the way for new studies of strongly interacting many-body systems.}, number={8}, journal={PHYSICAL REVIEW LETTERS}, author={Kangara, J. and Cheng, Chingyun and Pegahan, S. and Arakelyan, I. and Thomas, J. E.}, year={2018}, month={Feb} }
@article{cheng_kangara_arakelyan_thomas_2016, title={Fermi gases in the two-dimensional to quasi-two-dimensional crossover}, volume={94}, ISSN={["2469-9934"]}, DOI={10.1103/physreva.94.031606}, abstractNote={We tune the dimensionality of pancake-shaped strongly-interacting Li Fermi gas clouds from twodimensional (2D) to quasi-2D, by controlling the ratio of the radial Fermi energy EF to the harmonic oscillator energy hνz in the tightly confined direction. In the 2D regime, where EF << hνz, the measured radio frequency resonance spectra are in agreement with 2D-BCS theory. In the quasi-2D regime, where EF ≃ hνz, the measured spectra deviate significantly from 2D-BCS theory. For both regimes, the measured cloud radii disagree with 2D-BCS mean field theory, but agree approximately with predictions using a free energy derived from the Bethe-Goldstone equation.}, number={3}, journal={PHYSICAL REVIEW A}, author={Cheng, Chingyun and Kangara, J. and Arakelyan, I. and Thomas, J. E.}, year={2016}, month={Sep} }
@article{ong_cheng_arakelyan_thomas_2015, title={Spin-Imbalanced Quasi-Two-Dimensional Fermi Gases}, volume={114}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.114.110403}, abstractNote={We measure the density profiles for a Fermi gas of (6)Li containing N(1) spin-up atoms and N(2) spin-down atoms, confined in a quasi-two-dimensional geometry. The spatial profiles are measured as a function of spin imbalance N(2)/N(1) and interaction strength, which is controlled by means of a collisional (Feshbach) resonance. The measured cloud radii and central densities are in disagreement with mean-field Bardeen-Cooper-Schrieffer theory for a true two-dimensional system. We find that the data for normal-fluid mixtures are reasonably well fit by a simple two-dimensional polaron model of the free energy. Not predicted by the model is a phase transition to a spin-balanced central core, which is observed above a critical value of N(2)/N(1). Our observations provide important benchmarks for predictions of the phase structure of quasi-two-dimensional Fermi gases.}, number={11}, journal={PHYSICAL REVIEW LETTERS}, author={Ong, W. and Cheng, Chingyun and Arakelyan, I. and Thomas, J. E.}, year={2015}, month={Mar} }
@article{zhang_ong_arakelyan_thomas_2012, title={Polaron-to-Polaron Transitions in the Radio-Frequency Spectrum of a Quasi-Two-Dimensional Fermi Gas}, volume={108}, ISSN={["0031-9007"]}, DOI={10.1103/physrevlett.108.235302}, abstractNote={We measure radio-frequency spectra for a two-component mixture of a 6Li atomic Fermi gas in a quasi-two-dimensional regime with the Fermi energy comparable to the energy level spacing in the tightly confining potential. Near the Feshbach resonance, we find that the observed resonances do not correspond to transitions between confinement-induced dimers. The spectral shifts can be fit by assuming transitions between noninteracting polaron states in two dimensions.}, number={23}, journal={PHYSICAL REVIEW LETTERS}, author={Zhang, Y. and Ong, W. and Arakelyan, I. and Thomas, J. E.}, year={2012}, month={Jun} }