Rhys Anderson | Searcharxiv

arXiv2022

BaF molecules in neon ice: trapping, spectroscopy and optical control of electron spins

We have trapped BaF molecules in neon ice, and used laser-induced fluorescence spectroscopy to map out optical transitions in the trapped molecules. Our measurements show that the neon lattice does not significantly perturb certain optical transitions in the trapped molecules. We used one of these transitions to polarize the electron spins, detect spin flips and measure hyperfine transitions in the trapped molecules, entirely using lasers. This demonstration with heavy polar molecules opens up new opportunities for precision measurements of beyond-standard-model physics.

physics.atom-ph↗

arXiv2017

Conductivity spectrum of ultracold atoms in an optical lattice

We measure the conductivity of neutral fermions in a cubic optical lattice. Using in-situ fluorescence microscopy, we observe the alternating current resultant from a single-frequency uniform force applied by displacement of a weak harmonic trapping potential. In the linear response regime, a neutral-particle analogue of Ohm's law gives the conductivity as the ratio of total current to force. For various lattice depths, temperatures, interaction strengths, and fillings, we measure both real and imaginary conductivity, up to a frequency sufficient to capture the transport dynamics within the lowest band. The spectral width of the real conductivity reveals the current dissipation rate in the lattice, and the integrated spectral weight is related to thermodynamic properties of the system through a sum rule. The global conductivity decreases with increased band-averaged effective mass, which at high temperatures approaches a T-linear regime. Relaxation of current is observed to require a finite lattice depth, which breaks Galilean invariance and enables damping through collisions between fermions.

cond-mat.quant-gas↗