@article {1304,
title = {Self-heterodyne detection of the {\it in-situ} phase of an atomic-SQUID},
journal = {Physical Review A},
volume = {92},
year = {2015},
month = {2015/09/03},
pages = {033602},
abstract = { We present theoretical and experimental analysis of an interferometric
measurement of the {\it in-situ} phase drop across and current flow through a
rotating barrier in a toroidal Bose-Einstein condensate (BEC). This experiment
is the atomic analog of the rf-superconducting quantum interference device
(SQUID). The phase drop is extracted from a spiral-shaped density profile
created by the spatial interference of the expanding toroidal BEC and a
reference BEC after release from all trapping potentials. We characterize the
interferometer when it contains a single particle, which is initially in a
coherent superposition of a torus and reference state, as well as when it
contains a many-body state in the mean-field approximation. The single-particle
picture is sufficient to explain the origin of the spirals, to relate the
phase-drop across the barrier to the geometry of a spiral, and to bound the
expansion times for which the {\it in-situ} phase can be accurately determined.
Mean-field estimates and numerical simulations show that the inter-atomic
interactions shorten the expansion time scales compared to the single-particle
case. Finally, we compare the mean-field simulations with our experimental data
and confirm that the interferometer indeed accurately measures the {\it
in-situ} phase drop.
},
doi = {10.1103/PhysRevA.92.033602},
url = {http://arxiv.org/abs/1506.09149v2},
author = {Ranchu Mathew and Avinash Kumar and Stephen Eckel and Fred Jendrzejewski and Gretchen K. Campbell and Mark Edwards and Eite Tiesinga}
}
@article {1292,
title = {Tunneling phase gate for neutral atoms in a double-well lattice},
journal = {Physical Review A},
volume = {77},
year = {2008},
month = {2008/5/12},
abstract = { We propose a new two--qubit phase gate for ultra--cold atoms confined in an
experimentally realized tilted double--well optical lattice [Sebby--Strabley et
al., Phys. Rev. A {\bf 73} 033605 (2006)]. Such a lattice is capable of
confining pairs of atoms in a two--dimensional array of double--well potentials
where control can be exercised over the barrier height and the energy
difference of the minima of the two wells (known as the {\textquoteleft}{\textquoteleft}tilt{\textquoteright}{\textquoteright}). The four
lowest single--particle motional states consist of two pairs of motional states
in which each pair is localized on one side of the central barrier, allowing
for two atoms confined in such a lattice to be spatially separated qubits. We
present a time--dependent scheme to manipulate the tilt to induce tunneling
oscillations which produce a collisional phase gate. Numerical simulations
demonstrate that this gate can be performed with high fidelity.
},
doi = {10.1103/PhysRevA.77.050304},
url = {http://arxiv.org/abs/0712.1856v1},
author = {Frederick W. Strauch and Mark Edwards and Eite Tiesinga and Carl J. Williams and Charles W. Clark}
}
@article {1414,
title = {Bogoliubov approach to superfluidity of atoms in an optical lattice},
journal = {Journal of Physics B: Atomic, Molecular and Optical Physics},
volume = {36},
year = {2003},
month = {2003/03/14},
pages = {825 - 841},
abstract = { We use the Bogoliubov theory of atoms in an optical lattice to study the
approach to the Mott-insulator transition. We derive an explicit expression for
the superfluid density based on the rigidity of the system under phase
variations. This enables us to explore the connection between the quantum
depletion of the condensate and the quasi-momentum distribution on the one hand
and the superfluid fraction on the other. The approach to the insulator phase
may be characterized through the filling of the band by quantum depletion,
which should be directly observable via the matter wave interference patterns.
We complement these findings by self-consistent Hartree-Fock-Bogoliubov-Popov
calculations for one-dimensional lattices including the effects of a parabolic
trapping potential.
},
doi = {10.1088/0953-4075/36/5/304},
url = {http://arxiv.org/abs/cond-mat/0210550v2},
author = {Ana Maria Rey and Keith Burnett and Robert Roth and Mark Edwards and Carl J. Williams and Charles W. Clark}
}