Gapped momentum states

Entanglement and Ground States of Gapped Hamiltonians

Gapped Surface States in a Strong-Topological-Insulator Material.

A three-dimensional strong-topological insulator or semimetal hosts topological surface states which are often said to be gapless so long as time-reversal symmetry is preserved. This narrative can be mistaken when surface state degeneracies occur away from time-reversal-invariant momenta. The mirror invariance of the system then becomes essential in protecting the existence of a surface Fermi s...

Excitation of high angular momentum Rydberg states

We describe and analyse an RF-optical technique for exciting alkali atoms in an atomic beam to a specific high angular momentum Rydberg state. In the procedure the Rydberg states are dressed by an RF field and two optical photons are used to excite the dressed state that goes adiabatically into the desired Rydberg state as the RF field is turned off. We describe in detail the excitation of the ...

Squeezing on Momentum States for Atom Interferometry.

We propose and analyze a method that allows for the production of squeezed states of the atomic center-of-mass motion that can be injected into an atom interferometer. Our scheme employs dispersive probing in a ring resonator on a narrow transition in order to provide a collective measurement of the relative population of two momentum states. We show that this method is applicable to a Bragg di...

Momentum transfer in nonequilibrium steady states.

When a Brownian object interacts with noninteracting gas particles under nonequilibrium conditions, energy dissipation associated with Brownian motion causes an additional force on the object as a "momentum transfer deficit." This principle is demonstrated first by a new nonequilibrium steady state model and then applied to several known models such as an adiabatic piston for which a simple exp...