Dr. Guilherme de Sousa is the master (equation) of the universe
Congratulations Guilherme!
Category: Theory
Measurement resolution enhanced coherence for lattice fermions
Weak measurement enables the extraction of targeted information from a quantum system while minimizing decoherence due to measurement backaction. However, in many-body quantum systems, backaction can have unexpected effects on wave-function collapse. We theoretically study a minimal many-particle model consisting …
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Stationary solitary waves in F=1 spin-orbit-coupled Bose-Einstein condensates
We consider solitary wave excitations above the ground state of 𝐹=1 spin-orbit-coupled Bose-Einstein condensates (SOBECs). The low-energy properties of SOBECs in any of the three branches of the single-particle dispersion relation can be described by suitable scalar nonlinear Schrödinger (NLS) equations which we …
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Feedback-cooled Bose-Einstein condensation: Near and far from equilibrium
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 …
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Interference induced anisotropy in a two-dimensional dark state optical lattice
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 …
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Topological charge pumping with subwavelength Raman lattices
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 …
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Dr. Shangjie Guo defends his thesis!
On this day, April 4, 2022, Shangjie Guo defended his thesis. Congratulations Shangjie!
Feedback-stabilized dynamical steady states in the Bose-Hubbard model
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 …
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Wilson loop and Wilczek-Zee phase from a non-Abelian gauge field
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 …
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Machine-learning enhanced dark soliton detection in Bose–Einstein condensates
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 …
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