Arxiv Selection Jul 2020

Jul 1- Jul 7 Bhaskar Mukherjee, Jul 8- Jul 14 Zehan Li, Jul 15- Jul 21 Haiping Hu, Jul 22- Jul 28 Sayan Choudhury

Jul 8

arXiv:2007.03147 [pdf, ps, other]

Unidirectional spin transport of a spin-orbit-coupled atomic matter wave using a moving Dirac δ-potential well

Jieli Qin, Lu Zhou

Journal-ref: Phys. Rev. A 102, 013304 (2020)

Subjects: Quantum Gases (cond-mat.quant-gas)

We study the transport of a spin-orbit-coupled atomic matter wave using a moving Dirac δ- potential well. In a spin-orbit-coupled system, bound states can be formed in both ground and excited energy levels with a Dirac δ-potential. Because Galilean invariance is broken in a spin- orbit-coupled system, moving of the potential will induce a velocity-dependent effective detuning. This induced detuning breaks the spin symmetry and makes the ground-state transporting channel be spin-↑ (↓) favored while makes the excited state transporting channel be spin-↓ (↑) favored for a positive-direction (negative-direction) transporting. When the δ-potential well moves at a small velocity, both the ground-state and excited-state channels contribute to the transportation, and thus both the spin components can be efficiently transported. However, when the moving velocity of the δ-potential well exceeds a critical value, the induced detuning is large enough to eliminate the excited bound state, and makes the ground bound state the only transporting channel, in which only the spin-↑ (↓) component can be efficiently transported in a positive (negative) direction. This work demonstrates a prototype of unidirectional spin transport.

Jul 9

arXiv:2007.03723 (cross-list from physics.atom-ph) [pdf, other]

Collisional loss of one-dimensional fermions near a p-wave Feshbach resonance

Ya-Ting Chang, Ruwan Senaratne, Danyel Cavazos-Cavazos, Randall G. Hulet

Subjects: Atomic Physics (physics.atom-ph); Quantum Gases (cond-mat.quant-gas)

We study collisional loss of a quasi-one-dimensional (1D) spin-polarized Fermi gas near a p-wave Feshbach resonance in ultracold 6Li atoms. We measure the location of the p-wave resonance in quasi-1D and observe a confinement-induced shift and broadening. We find that the three-body loss coefficient L3 as a function of the quasi-1D confinement has little dependence on confinement strength. We also analyze the atom loss with a two-step cascade three-body loss model in which weakly bound dimers are formed prior to their loss arising from atom-dimer collisions. Our data are consistent with this model. We also find a possible suppression in the rate of dimer relaxation with strong quasi-1D confinement. We discuss the implications of these measurements for observing p-wave pairing in quasi-1D.

Jul 10

arXiv:2007.04745 [pdf, other]

Many-body localization of bosons in optical lattice: Dynamics in disorder-free potentials

Ruixiao Yao, Jakub Zakrzewski

Comments: 10pp. comments welcome

Subjects: Quantum Gases (cond-mat.quant-gas); Disordered Systems and Neural Networks (cond-mat.dis-nn); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)

The phenomenon of Many-Body Stark Localization of bosons in tilted optical lattice is studied. Despite the fact that no disorder is necessary for Stark localization to occur, it is very similar to well known many body localization (MBL) in sufficiently strong disorder. Not only the mean gap ratio reaches poissonian value as characteristic for localized situations but also the eigenstates reveal multifractal character as in standard MBL. Stark localization enables a coexistence of spacially separated thermal and localized phases in the harmonic trap similarly to fermions. Stark localization may also lead to spectacular trapping of particles in a reversed harmonic field which naively might be considered as an unstable configuration.

Jul 13

arXiv:2007.05241 [pdf, other]

Engineering entanglement Hamiltonians with strongly interacting cold atoms in optical traps

R. E. Barfknecht, T. Mendes-Santos, L. Fallani

Comments: 11 pages, 6 figures

Subjects: Quantum Gases (cond-mat.quant-gas); Quantum Physics (quant-ph)

We present a proposal for the realization of entanglement Hamiltonians in one-dimensional critical spin systems with strongly interacting cold atoms. Our approach is based on the notion that the entanglement spectrum of such systems can be realized with a physical Hamiltonian containing a set of position-dependent couplings. We focus on reproducing the universal ratios of the entanglement spectrum for systems in two different geometries: a harmonic trap, which corresponds to a partition embedded in an infinite system, and a linear potential, which reproduces the properties of a half- partition with open boundary conditions. Our results demonstrate the possibility of measuring the entanglement spectra of the Heisenberg and XX models in a realistic cold-atom experimental setting by simply using gravity and standard trapping techniques.

Jul 14

arXiv:2007.06391 [pdf, other]

New states of matter with fine-tuned interactions: quantum droplets and dipolar supersolids

Fabian Böttcher, Jan-Niklas Schmidt, Jens Hertkorn, Kevin S. H. Ng, Sean D. Graham, Mingyang Guo, Tim Langen, Tilman Pfau

Subjects: Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph)

Quantum fluctuations can stabilize Bose-Einstein condensates (BEC) against the mean-field collapse. Stabilization of the condensate has been observed in quantum degenerate Bose-Bose mixtures and dipolar BECs. The fine-tuning of the interatomic interactions can lead to the emergence of two new states of matter: liquid-like self- bound quantum droplets and supersolid crystals formed from these droplets. We review the properties of these exotic states of matter and summarize the experimental progress made using dipolar quantum gases and Bose-Bose mixtures. We conclude with an outline of important open questions that could be addressed in the future.