Continuously measured interacting quantum systems almost invariably heat, causing loss of quantum coherence. Here, we study Bose-Einstein condensates (BECs) subject to repeated weak measurement of the atomic density and describe several protocols for generating a feedback signal designed to remove …
Feedback-cooled Bose-Einstein condensation: Near and far from equilibrium Read more »
We describe a two-dimensional optical lattice for ultracold atoms with spatial features below the diffraction limit created by a bichromatic optical standing wave. At every point in space these fields couple the internal atomic states in a three-level Lambda coupling …
Interference induced anisotropy in a two-dimensional dark state optical lattice Read more »
Recent experiments demonstrated deeply subwavelength lattices using atoms with N internal states Raman coupled with lasers of wavelength λ. The resulting unit cell was λ/2N in extent, an N-fold reduction compared to the usual λ/2 periodicity of an optical lattice. For resonant Raman coupling, this lattice consists of N independent …
Topological charge pumping with subwavelength Raman lattices Read more »
On this day, April 4, 2022, Shangjie Guo defended his thesis. Congratulations Shangjie!
The implementation of a combination of continuous weak measurement and classical feedback provides a powerful tool for controlling the evolution of quantum systems. In this paper, we investigate the potential of this approach from three perspectives. First, we consider a …
Feedback-stabilized dynamical steady states in the Bose-Hubbard model Read more »
Quantum states can acquire a geometric phase called the Berry phase after adiabatically traversing a closed loop, which depends on the path not the rate of motion. The Berry phase is analogous to the Aharonov–Bohm phase derived from the electromagnetic …
Wilson loop and Wilczek-Zee phase from a non-Abelian gauge field Read more »
Most data in cold-atom experiments comes from images, the analysis of which is limited by our preconceptions of the patterns that could be present in the data. We focus on the well-defined case of detecting dark solitons—appearing as local density …
Machine-learning enhanced dark soliton detection in Bose–Einstein condensates Read more »
Spielman group alumna Dr. Dina Genkina has composed a high level write-up of Dr. Ana Valdés-Curiel’s Rashba paper! https://jqi.umd.edu/news/researchers-comb-atoms-into-novel-swirl Topological features without a lattice in Rashba spin-orbit coupled atoms; A. Valdés-Curiel, D. Trypogeorgos, Q.-Y. Liang, R. P. Anderson, and I. …
Topological order can be found in a wide range of physical systems, from crystalline solids, photonic meta-materials and even atmospheric waves to optomechanic, acoustic and atomic systems. Topological systems are a robust foundation for creating quantized channels for transporting electrical …
Topological features without a lattice in Rashba spin-orbit coupled atoms Read more »
Weak measurement in tandem with real-time feedback control is a new route toward engineering novel nonequilibrium quantum matter. Here we develop a theoretical toolbox for quantum feedback control of multicomponent Bose-Einstein condensates (BECs) using backaction-limited weak measurements in conjunction with …
Feedback induced magnetic phases in binary Bose-Einstein condensates Read more »