Studies of Lattice-Based Atomic Quantum Systems with Engineered Dissipation

The goal of this project is to understand and control the damping of small quantum systems coupled to an environment. Quantum mechanics is reversible, that is, a hypothetical movie of a quantum system looks the same if it is played forward or in reverse. So how can damping, something non-reversible, emerge in quantum physics? This project aims to engineer a simple model system consisting of an "atomic quantum dot" (an artificial atom) coupled to an empty vacuum, the simplest of all environments. This tunable experimental system, which emits matter waves rather than optical radiation, will allow for precise investigation of damping as the structure of the environment is changed. It should be possible to build laser-like sources using a large number of regularly spaced atomic quantum dots, and to exploit the coupling to the environment for a novel form of quantum tunneling, which may find use in quantum simulation of solid-state phenomena. While this first set of experiments sheds light on the nature of quantum mechanical damping, a second set of experiments will investigate whether such damping due to a large environment can be avoided. Here, the model system considered will consist of an atom moving through a one-dimensional atomic gas in a tube-like geometry. Collisions should slow down the atom and damp its motion completely, but it may be possible to harness quantum mechanics to shield the atomic motion by rendering the environment effectively transparent, such that damping is suppressed. Developing ways to control damping and dissipation are of paramount importance for quantum simulation and quantum information science, and the results of this project will be of relevance in addressing some of the fundamental challenges. The project is devoted to the experimental study of novel dissipative systems in the context of ultracold atomic physics, focusing on engineered atomic quantum dots and mobile impurities coupled to a bosonic environment with controllable many-body character. The implementation of such systems is made possible through the use of ultracold, homonuclear atomic mixtures with hyperfine-state components that are independently controlled with state-dependent optical potentials. The project goals include an exploration of spontaneous and superradiant matter-wave emission, of couplings induced by evanescent matter-wave fields arising from coherent dressing, as well as couplings provided by phononic excitations of a superfluid environment, with the prospect of realizing a dissipative quantum Ising chain. Exploiting the coupling to one-dimensional Bose gases, the project furthermore aims to investigate dissipative and coherent transport for unconfined impurities near integrability, with the prospect of observing novel many-body effects.