arXiv subjects

Da-wei Wang

Publications and source records attributed to Da-wei Wang.

3 recordsLinked to original sources

arXiv2020

Many-body chiral edge currents and sliding phases of atomic spinwaves in momentum-space lattice

Collective excitations (spinwaves) of long-lived atomic hyperfine states can be synthesized into a Bose-Hubbard model in momentum space. We explore many-body ground states and dynamics of a two-leg momentum-space lattice formed by two coupled hyperfine states. Essential ingredients of this setting are a staggered artificial magnetic field engineered by lasers that couple the spinwave states, and a state-dependent long-range interaction, which is induced by laser-dressing a hyperfine state to a Rydberg state. The Rydberg dressed two-body interaction gives rise to a state-dependent blockade in momentum space, and can amplify staggered flux induced anti-chiral edge currents in the many-body ground state in the presence of magnetic flux. When the Rydberg dressing is applied to both hyperfine states, exotic sliding insulating and superfluid/supersolid phases emerge. Due to the Rydberg dressed long-range interaction, spinwaves slide along a leg of the momentum-space lattice without costing energy. Our study paves a route to the quantum simulation of topological phases and exotic dynamics with interacting spinwaves of atomic hyperfine states in momentum-space lattice.

cond-mat.quant-gas↗

arXiv2017

How isolated is enough for an "isolated" system in statistical mechanics?

Irreversible processes are frequently adopted to account for the entropy increase in classical thermodynamics. However, the corresponding physical origins are not always clear, e.g. in a free expansion process, a typical model in textbooks. In this letter, we study the entropy change during free expansion for a particle with the thermal de Broglie wavelength ($λ_{T}$) in a one-dimensional square trap with size $L$. By solely including quantum dephasing as an irreversible process, we recover classical result of entropy increase in the classical region ($L\ggλ_{T}$), while predict prominent discrepancies in the quantum region ($L\llλ_{T}$) because of non-equilibrium feature of trapped atoms after expansion. It is interesting to notice that the dephasing, though absent in classical system, is critical to clarify mysteries in classical thermodynamics.

quant-ph↗

arXiv2016

Synthetic gauge potential and effective magnetic field in a Raman medium undergoing molecular modulation

We theoretically demonstrate non-trivial topological effects for a probe field in a Raman medium undergoing molecular modulation processes. The medium is driven by two non-collinear pump beams. We show that the angle between the pumps is related to an effective gauge potential and an effective magnetic field for the probe field in the synthetic space consisting of a synthetic frequency dimension and a spatial dimension. As a result of such effective magnetic field, the probe field can exhibit topologically-protected one-way edge state in the synthetic space, as well as Landau levels which manifests as suppression of both diffraction and sideband generation. Our work identifies a previously unexplored route towards creating topological photonics effects, and highlights an important connection between topological photonics and nonlinear optics.

physics.optics↗