@article {1201,
title = {Topological Flat Bands from Dipolar Spin Systems},
journal = {Physical Review Letters},
volume = {109},
year = {2012},
month = {2012/12/26},
abstract = { We propose and analyze a physical system that naturally admits
two-dimensional topological nearly flat bands. Our approach utilizes an array
of three-level dipoles (effective S = 1 spins) driven by inhomogeneous
electromagnetic fields. The dipolar interactions produce arbitrary uniform
background gauge fields for an effective collection of conserved hardcore
bosons, namely, the dressed spin-flips. These gauge fields result in
topological band structures, whose bandgap can be larger than the corresponding
bandwidth. Exact diagonalization of the full interacting Hamiltonian at
half-filling reveals the existence of superfluid, crystalline, and supersolid
phases. An experimental realization using either ultra-cold polar molecules or
spins in the solid state is considered.
},
doi = {10.1103/PhysRevLett.109.266804},
url = {http://arxiv.org/abs/1207.4479v3},
author = {Norman Y. Yao and Chris R. Laumann and Alexey V. Gorshkov and Steven D. Bennett and Eugene Demler and Peter Zoller and Mikhail D. Lukin}
}
@article {1181,
title = {Quantum Magnetism with Polar Alkali Dimers},
journal = {Physical Review A},
volume = {84},
year = {2011},
month = {2011/9/15},
abstract = { We show that dipolar interactions between ultracold polar alkali dimers in
optical lattices can be used to realize a highly tunable generalization of the
t-J model, which we refer to as the t-J-V-W model. The model features
long-range spin-spin interactions J_z and J_perp of XXZ type, long-range
density-density interaction V, and long-range density-spin interaction W, all
of which can be controlled in both magnitude and sign independently of each
other and of the tunneling t. The "spin" is encoded in the rotational degree of
freedom of the molecules, while the interactions are controlled by applied
static electric and continuous-wave microwave fields. Furthermore, we show that
nuclear spins of the molecules can be used to implement an additional (orbital)
degree of freedom that is coupled to the original rotational degree of freedom
in a tunable way. The presented system is expected to exhibit exotic physics
and to provide insights into strongly correlated phenomena in condensed matter
systems. Realistic experimental imperfections are discussed.
},
doi = {10.1103/PhysRevA.84.033619},
url = {http://arxiv.org/abs/1106.1655v1},
author = {Alexey V. Gorshkov and Salvatore R. Manmana and Gang Chen and Eugene Demler and Mikhail D. Lukin and Ana Maria Rey}
}
@article {1198,
title = {Tunable Superfluidity and Quantum Magnetism with Ultracold Polar Molecules
},
journal = {Physical Review Letters},
volume = {107},
year = {2011},
month = {2011/9/8},
abstract = { By selecting two dressed rotational states of ultracold polar molecules in an
optical lattice, we obtain a highly tunable generalization of the t-J model,
which we refer to as the t-J-V-W model. In addition to XXZ spin exchange, the
model features density-density interactions and novel density-spin
interactions; all interactions are dipolar. We show that full control of all
interaction parameters in both magnitude and sign can be achieved independently
of each other and of the tunneling. As a first step towards demonstrating the
potential of the system, we apply the density matrix renormalization group
method (DMRG) to obtain the 1D phase diagram of the simplest experimentally
realizable case. Specifically, we show that the tunability and the long-range
nature of the interactions in the t-J-V-W model enable enhanced superfluidity.
Finally, we show that Bloch oscillations in a tilted lattice can be used to
probe the phase diagram experimentally.
},
doi = {10.1103/PhysRevLett.107.115301},
url = {http://arxiv.org/abs/1106.1644v1},
author = {Alexey V. Gorshkov and Salvatore R. Manmana and Gang Chen and Jun Ye and Eugene Demler and Mikhail D. Lukin and Ana Maria Rey}
}
@article {1501,
title = {Adiabatic preparation of many-body states in optical lattices},
journal = {Physical Review A},
volume = {81},
year = {2010},
month = {2010/6/22},
abstract = { We analyze a technique for the preparation of low entropy many body states of
atoms in optical lattices based on adiabatic passage. In particular, we show
that this method allows preparation of strongly correlated states as stable
highest energy states of Hamiltonians that have trivial ground states. As an
example, we analyze the generation of antiferromagnetically ordered states by
adiabatic change of a staggered field acting on the spins of bosonic atoms with
ferromagnetic interactions.
},
doi = {10.1103/PhysRevA.81.061603},
url = {http://arxiv.org/abs/0906.2567v3},
author = {Anders S. Sorensen and Ehud Altman and Michael Gullans and J. V. Porto and Mikhail D. Lukin and Eugene Demler}
}
@article {1170,
title = {Photonic Phase Gate via an Exchange of Fermionic Spin Waves in a Spin Chain
},
journal = {Physical Review Letters},
volume = {105},
year = {2010},
month = {2010/8/5},
abstract = { We propose a new protocol for implementing the two-qubit photonic phase gate.
In our approach, the pi phase is acquired by mapping two single photons into
atomic excitations with fermionic character and exchanging their positions. The
fermionic excitations are realized as spin waves in a spin chain, while photon
storage techniques provide the interface between the photons and the spin
waves. Possible imperfections and experimental systems suitable for
implementing the gate are discussed.
},
doi = {10.1103/PhysRevLett.105.060502},
url = {http://arxiv.org/abs/1001.0968v3},
author = {Alexey V. Gorshkov and Johannes Otterbach and Eugene Demler and Michael Fleischhauer and Mikhail D. Lukin}
}
@article {1192,
title = {Anyonic interferometry and protected memories in atomic spin lattices},
journal = {Nature Physics},
volume = {4},
year = {2008},
month = {2008/4/20},
pages = {482 - 488},
abstract = { Strongly correlated quantum systems can exhibit exotic behavior called
topological order which is characterized by non-local correlations that depend
on the system topology. Such systems can exhibit remarkable phenomena such as
quasi-particles with anyonic statistics and have been proposed as candidates
for naturally fault-tolerant quantum computation. Despite these remarkable
properties, anyons have never been observed in nature directly. Here we
describe how to unambiguously detect and characterize such states in recently
proposed spin lattice realizations using ultra-cold atoms or molecules trapped
in an optical lattice. We propose an experimentally feasible technique to
access non-local degrees of freedom by performing global operations on trapped
spins mediated by an optical cavity mode. We show how to reliably read and
write topologically protected quantum memory using an atomic or photonic qubit.
Furthermore, our technique can be used to probe statistics and dynamics of
anyonic excitations.
},
doi = {10.1038/nphys943},
url = {http://arxiv.org/abs/0711.1365v1},
author = {Liang Jiang and Gavin K. Brennen and Alexey V. Gorshkov and Klemens Hammerer and Mohammad Hafezi and Eugene Demler and Mikhail D. Lukin and Peter Zoller}
}