# ultracold

## Experimental realization of U(1) gauge invariance in ultracold atomic mixtures

This thesis reports on the experimental realization of an elementary building block for analog quantum simulation of a U(1) lattice gauge theory in a mixture of two bosonic quantum gases. Experimentally, the building block is realized by …

## Elastic Scattering Time of Matter Waves in Disordered Potentials

We report on the direct measurement of the elastic scattering time $\tau_S$ of ultracold atoms propagating in optical disordered potentials. By exploring this fundamental quantity over a large range of experimental parameters, we observe variations …

## Implementing an Optical Accordion Lattice for the Realization of a Quantized Otto Cycle

This thesis presents design and characterization of a versatile optical standingwave trap for lithium atoms. Using this trap, an implementation of a quantized Otto cycle with the sodium-lithium mixture experiment that cools down a cloud of sodium …

## Coherent optical nano-tweezers for ultra-cold atoms

There has been a recent surge of interest and progress in creating subwavelength free-space optical potentials for ultracold atoms. A key open question is whether geometric potentials, which are repulsive and ubiquitous in the creation of …

## Temperature induced decay of persistent currents in superfluid ultracold gas

We study how temperature affects the lifetime of a quantized, persistent current state in a toroidal Bose-Einstein condensate. When the temperature is increased, we find a decrease in the persistent current lifetime. Comparing our measured decay …

## Design and Implementation of a Versatile Imaging Objective for Imaging of Ultracold Mixtures of Sodium and Lithium

This thesis presents the design and implementation of a high resolution objective lens for imaging ultracold atomic clouds of sodium and lithium in the NaLi experiment. The lens has been developed using the ray tracing software OSLO. The design …

## Contact resistance and phase slips in mesoscopic superfluid-atom transport

We have experimentally measured transport of superfluid, bosonic atoms in a mesoscopic system: a small channel connecting two large reservoirs. Starting far from equilibrium (superfluid in a single reservoir), we observe first resistive flow …

## Subwavelength-width optical tunnel junctions for ultracold atoms

We propose a new method for creating far-field optical barrier potentials for ultracold atoms with widths that are narrower than the diffraction limit and can approach tens of nanometers. The reduced widths stem from the nonlinear atomic response to …

## Self-heterodyne detection of the in situ phase of an atomic superconducting quantum interference device

We present theoretical and experimental analysis of an interferometric measurement of the in situ phase drop across and current flow through a rotating barrier in a toroidal Bose-Einstein condensate (BEC). This experiment is the atomic analog of the …

## Hysteresis in a quantized superfluid 'atomtronic' circuit

Atomtronics is an emerging interdisciplinary field that seeks to develop new functional methods by creating devices and circuits where ultracold atoms, often superfluids, have a role analogous to that of electrons in electronics. Hysteresis is widely …