Category: Papers Published

Vortex nucleation in a Bose–Einstein condensate: from the inside out

We observed a new mechanism for vortex nucleation in Bose–Einstein condensates (BECs) subject to synthetic magnetic fields. We made use of a strong synthetic magnetic field initially localized between a pair of merging BECs to rapidly create vortices in the

Tutorial: Synthetic gauge potentials for ultracold neutral atoms

Synthetic gauge fields for ultracold neutral atoms—engineered using the interaction between laser fields and the atoms’ internal ‘spin’ degrees of freedom—provide promising techniques for generating the large (synthetic) magnetic fields required to reach the fractional quantum Hall (FQH) limit in

Geometrical Pumping with a Bose-Einstein Condensate

We realized a quantum geometric “charge” pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice [JQI writeup]. Topological charge pumps in filled bands yield quantized pumping set by the global—topological—properties of the

Rashba realization: Raman with RF

We theoretically explore a Rashba spin–orbit coupling scheme which operates entirely in the absolute ground state manifold of an alkali atom, thereby minimizing all inelastic processes. An energy gap between ground eigenstates of the proposed coupling can be continuously opened

Magnetic phases of spin-1 spin–orbit-coupled Bose gases

Phases of matter are characterized by order parameters describing the type and degree of order in a system. Here we experimentally explore the magnetic phases present in a near-zero temperature spin-1 spin–orbit-coupled atomic Bose gas and the quantum phase transitions

Interaction-driven exotic quantum phases in spin-orbit-coupled spin-1 bosons

We study the interplay between large-spin, spin-orbit coupling, and superfluidity for bosons in a two-dimensional optical lattice, focusing on the spin-1 spin-orbit-coupled system recently realized at the Joint Quantum Institute [Campbell et al., arXiv:1501.05984]. We find a rich quantum phase

Feshbach enhanced s-wave scattering of fermions: direct observation with optimized absorption imaging

We directly measured the normalized s-wave scattering cross-section of ultracold 40K atoms across a magnetic-field Feshbach resonance by colliding pairs of degenerate Fermi gases (DFGs) and imaging the scattered atoms. We extracted the scattered fraction for a range of bias

Dynamical Detection of Topological Phase Transitions in Short-Lived Atomic Systems

We demonstrate that dynamical probes provide direct means of detecting the topological phase transition (TPT) between conventional and topological phases, which would otherwise be difficult to access because of loss or heating processes. We propose to avoid such heating by

Published in Science: Visualizing edge states with an atomic Bose gas in the quantum Hall regime

Bringing ultracold atomic gases into the quantum Hall regime is challenging. We engineered an effective magnetic field in a two-dimensional lattice with an elongated-strip geometry, consisting of the sites of an optical lattice in the long direction and of three

Gauge matters: observing the vortex-nucleation transition in a Bose condensate

The order parameter of a quantum-coherent many-body system can include a phase degree of freedom, which, in the presence of an electromagnetic field, depends on the choice of gauge. Because of the relationship between the phase gradient and the velocity,