Super-resolution Control of Ultracold Dipolar Atoms on a 50-nm Scale

Abstract

Degenerate quantum gases of magnetic atoms such as dysprosium (Dy) and erbium (Er) offer new opportunities to quantum simulation research due to their large spin degree of freedom and long-range dipole-dipole interactions. In this thesis, following an introduction to the fundamental properties of Dy, we introduce the design and construction of an experimental apparatus that is capable of producing Bose-Eintein codensates of more than 10⁵ Dy atoms in every 10 seconds. In addition, we describe two experiments that advances the quantum control over the spin, the motion, the interaction, and the dynamics of ultracold dipolar gases.

In the first experiment, we introduce a super-resolution control scheme using a spin-dependent optical potential that localizes Dy atoms on a sub-50 nm scale, a distance that is more than 10 times shorter than the optical wavelength. With the interatomic distances shortened by a factor of 10, the interatomic dipole-dipole interaction is significantly enhanced. We will discuss how this strong and tunable long-range interaction enables the simulation of new classes of many-body Hamiltonians. We experimentally demonstrate the super-resolution technique by creating a bilayer of ultracold Dy atoms and mapping out the atomic density distribution with sub-10 nm resolution. The interlayer dipole-dipole interaction are detected via two out-of-equilibrium experiments.

In the second experiment, we study the suppression of dipolar relaxation, an inelastic process that limits the lifetime of higher spin states, using external optical confinements. By confining ultracold dysprosium atoms in ultrathin optical layers, the magnetic atoms can approach each other only side by side. The interatomic dipole-dipole repulsion provides a protective shield that stops the atoms from tunneling to short-range. We observe an order of magnitude suppression of inelastic dipolar relaxation losses in the presence of the dipolar shield. This scheme can extend the lifetime of quantum gases of spin mixtures, thereby offering more opportunities for exploring physics such as spin-orbit coupled Bose gases, dipolar spinor condensates, etc.