Eric L. Hazlett | Searcharxiv

arXiv2013

Anomalous thermoelectric transport in two-dimensional Bose gas

In condensed matter physics, transport measurements are essential not only for the characterization of materials, but also to discern between quantum phases and identify new ones. The extension of these measurements into atomic quantum gases is emerging and will expand the scope of quantum simulation and atomtronics. To push this frontier, we demonstrate an innovative approach to extract transport properties from the time-resolved redistribution of the particles and energy of a trapped atomic gas. Based on the two-dimensional (2D) Bose gas subject to weak three-body recombination we find clear evidence of both conductive and thermoelectric currents. We then identify the contributions to the currents from thermoelectric forces and determine the Seebeck coefficient (a.k.a. thermopower) and Lorenz number, both showing anomalous behavior in the fluctuation and superfluid regimes. Our results call for further exploration of the transport properties, particularly thermoelectric properties, of atomic quantum gases.

cond-mat.quant-gas↗

arXiv2012

S-Wave Collisional Frequency Shift of a Fermion Clock

We report an s-wave collisional frequency shift of an atomic clock based on fermions. In contrast to bosons, the fermion clock shift is insensitive to the population difference of the clock states, set by the first pulse area in Ramsey spectroscopy, θ_1. The fermion shift instead depends strongly on the second pulse area θ_2. It allows the shift to be canceled, nominally at θ_2 = π/2, but correlations shift the null to slightly larger θ_2. The shift applies to optical lattice clocks and increases with the spatial inhomogeneity of the clock excitation field, naturally large at optical frequencies.

physics.atom-ph↗