@article {1480,
title = {Many-body dynamics of dipolar molecules in an optical lattice},
journal = {Physical Review Letters},
volume = {113},
year = {2014},
month = {2014/11/7},
abstract = { Understanding the many-body dynamics of isolated quantum systems is one of
the central challenges in modern physics. To this end, the direct experimental
realization of strongly correlated quantum systems allows one to gain insights
into the emergence of complex phenomena. Such insights enable the development
of theoretical tools that broaden our understanding. Here, we theoretically
model and experimentally probe with Ramsey spectroscopy the quantum dynamics of
disordered, dipolar-interacting, ultracold molecules in a partially filled
optical lattice. We report the capability to control the dipolar interaction
strength, and we demonstrate that the many-body dynamics extends well beyond a
nearest-neighbor or mean-field picture, and cannot be quantitatively described
using previously available theoretical tools. We develop a novel cluster
expansion technique and demonstrate that our theoretical method accurately
captures the measured dependence of the spin dynamics on molecule number and on
the dipolar interaction strength. In the spirit of quantum simulation, this
agreement simultaneously benchmarks the new theoretical method and verifies our
microscopic understanding of the experiment. Our findings pave the way for
numerous applications in quantum information science, metrology, and condensed
matter physics.
},
doi = {10.1103/PhysRevLett.113.195302},
url = {http://arxiv.org/abs/1402.2354v1},
author = {Kaden R. A. Hazzard and Bryce Gadway and Michael Foss-Feig and Bo Yan and Steven A. Moses and Jacob P. Covey and Norman Y. Yao and Mikhail D. Lukin and Jun Ye and Deborah S. Jin and Ana Maria Rey}
}
@article {1478,
title = {Quantum correlations and entanglement in far-from-equilibrium spin systems
},
journal = {Physical Review A},
volume = {90},
year = {2014},
month = {2014/12/15},
abstract = { By applying complementary analytic and numerical methods, we investigate the
dynamics of spin-$1/2$ XXZ models with variable-range interactions in arbitrary
dimensions. The dynamics we consider is initiated from uncorrelated states that
are easily prepared in experiments, and can be equivalently viewed as either
Ramsey spectroscopy or a quantum quench. Our primary focus is the dynamical
emergence of correlations and entanglement in these far-from-equilibrium
interacting quantum systems: we characterize these correlations by the
entanglement entropy, concurrence, and squeezing, which are inequivalent
measures of entanglement corresponding to different quantum resources. In one
spatial dimension, we show that the time evolution of correlation functions
manifests a non-perturbative dynamic singularity. This singularity is
characterized by a universal power-law exponent that is insensitive to small
perturbations. Explicit realizations of these models in current experiments
using polar molecules, trapped ions, Rydberg atoms, magnetic atoms, and
alkaline-earth and alkali atoms in optical lattices, along with the relative
merits and limitations of these different systems, are discussed.
},
doi = {10.1103/PhysRevA.90.063622},
url = {http://arxiv.org/abs/1406.0937v1},
author = {Kaden R. A. Hazzard and Mauritz van den Worm and Michael Foss-Feig and Salvatore R. Manmana and Emanuele Dalla Torre and Tilman Pfau and Michael Kastner and Ana Maria Rey}
}
@article {1479,
title = {Suppressing the loss of ultracold molecules via the continuous quantum Zeno effect
},
journal = {Physical Review Letters},
volume = {112},
year = {2014},
month = {2014/2/20},
abstract = { We investigate theoretically the suppression of two-body losses when the
on-site loss rate is larger than all other energy scales in a lattice. This
work quantitatively explains the recently observed suppression of chemical
reactions between two rotational states of fermionic KRb molecules confined in
one-dimensional tubes with a weak lattice along the tubes [Yan et al., Nature
501, 521-525 (2013)]. New loss rate measurements performed for different
lattice parameters but under controlled initial conditions allow us to show
that the loss suppression is a consequence of the combined effects of lattice
confinement and the continuous quantum Zeno effect. A key finding, relevant for
generic strongly reactive systems, is that while a single-band theory can
qualitatively describe the data, a quantitative analysis must include multiband
effects. Accounting for these effects reduces the inferred molecule filling
fraction by a factor of five. A rate equation can describe much of the data,
but to properly reproduce the loss dynamics with a fixed filling fraction for
all lattice parameters we develop a mean-field model and benchmark it with
numerically exact time-dependent density matrix renormalization group
calculations.
},
doi = {10.1103/PhysRevLett.112.070404},
url = {http://arxiv.org/abs/1310.2221v2},
author = {Bihui Zhu and Bryce Gadway and Michael Foss-Feig and Johannes Schachenmayer and Michael Wall and Kaden R. A. Hazzard and Bo Yan and Steven A. Moses and Jacob P. Covey and Deborah S. Jin and Jun Ye and Murray Holland and Ana Maria Rey}
}
@article {1474,
title = {Far from equilibrium quantum magnetism with ultracold polar molecules},
journal = {Physical Review Letters},
volume = {110},
year = {2013},
month = {2013/2/11},
abstract = { Recent theory has indicated how to emulate tunable models of quantum
magnetism with ultracold polar molecules. Here we show that present molecule
optical lattice experiments can accomplish three crucial goals for quantum
emulation, despite currently being well below unit filling and not quantum
degenerate. The first is to verify and benchmark the models proposed to
describe these systems. The second is to prepare correlated and possibly useful
states in well-understood regimes. The third is to explore many-body physics
inaccessible to existing theoretical techniques. Our proposal relies on a
non-equilibrium protocol that can be viewed either as Ramsey spectroscopy or an
interaction quench. It uses only routine experimental tools available in any
ultracold molecule experiment.
},
doi = {10.1103/PhysRevLett.110.075301},
url = {http://arxiv.org/abs/1209.4076v1},
author = {Kaden R. A. Hazzard and Salvatore R. Manmana and Michael Foss-Feig and Ana Maria Rey}
}
@article {1175,
title = {Kitaev honeycomb and other exotic spin models with polar molecules},
journal = {Molecular Physics},
volume = {111},
year = {2013},
month = {2013/01/01},
pages = {1908 - 1916},
abstract = { We show that ultracold polar molecules pinned in an optical lattice can be
used to access a variety of exotic spin models, including the Kitaev honeycomb
model. Treating each molecule as a rigid rotor, we use DC electric and
microwave fields to define superpositions of rotational levels as effective
spin degrees of freedom, while dipole-dipole interactions give rise to
interactions between the spins. In particular, we show that, with sufficient
microwave control, the interaction between two spins can be written as a sum of
five independently controllable Hamiltonian terms proportional to the five
rank-2 spherical harmonics Y_{2,q}(theta,phi), where (theta,phi) are the
spherical coordinates of the vector connecting the two molecules. To
demonstrate the potential of this approach beyond the simplest examples studied
in [S. R. Manmana et al., arXiv:1210.5518v2], we focus on the realization of
the Kitaev honeycomb model, which can support exotic non-Abelian anyonic
excitations. We also discuss the possibility of generating spin Hamiltonians
with arbitrary spin S, including those exhibiting SU(N=2S+1) symmetry.
},
doi = {10.1080/00268976.2013.800604},
url = {http://arxiv.org/abs/1301.5636v1},
author = {Alexey V. Gorshkov and Kaden R. A. Hazzard and Ana Maria Rey}
}
@article {1471,
title = {Non-equilibrium dynamics of Ising models with decoherence: an exact solution
},
journal = {Physical Review A},
volume = {87},
year = {2013},
month = {2013/4/3},
abstract = { The interplay between interactions and decoherence in many-body systems is of
fundamental importance in quantum physics: Decoherence can degrade
correlations, but can also give rise to a variety of rich dynamical and
steady-state behaviors. We obtain an exact analytic solution for the
non-equilibrium dynamics of Ising models with arbitrary interactions and
subject to the most general form of local Markovian decoherence. Our solution
shows that decoherence affects the relaxation of observables more than
predicted by single-particle considerations. It also reveals a dynamical phase
transition, specifically a Hopf bifurcation, which is absent at the
single-particle level. These calculations are applicable to ongoing quantum
information and emulation efforts using a variety of atomic, molecular,
optical, and solid-state systems.
},
doi = {10.1103/PhysRevA.87.042101},
url = {http://arxiv.org/abs/1209.5795v2},
author = {Michael Foss-Feig and Kaden R. A. Hazzard and John J. Bollinger and Ana Maria Rey}
}
@article {1184,
title = {Topological phases in ultracold polar-molecule quantum magnets},
journal = {Physical Review B},
volume = {87},
year = {2013},
month = {2013/2/26},
abstract = { We show how to use polar molecules in an optical lattice to engineer quantum
spin models with arbitrary spin S >= 1/2 and with interactions featuring a
direction-dependent spin anisotropy. This is achieved by encoding the effective
spin degrees of freedom in microwave-dressed rotational states of the molecules
and by coupling the spins through dipolar interactions. We demonstrate how one
of the experimentally most accessible anisotropies stabilizes symmetry
protected topological phases in spin ladders. Using the numerically exact
density matrix renormalization group method, we find that these interacting
phases -- previously studied only in the nearest-neighbor case -- survive in
the presence of long-range dipolar interactions. We also show how to use our
approach to realize the bilinear-biquadratic spin-1 and the Kitaev honeycomb
models. Experimental detection schemes and imperfections are discussed.
},
doi = {10.1103/PhysRevB.87.081106},
url = {http://arxiv.org/abs/1210.5518v2},
author = {Salvatore R. Manmana and E. M. Stoudenmire and Kaden R. A. Hazzard and Ana Maria Rey and Alexey V. Gorshkov}
}
@article {1172,
title = {Spectroscopy of dipolar fermions in 2D pancakes and 3D lattices},
journal = {Physical Review A},
volume = {84},
year = {2011},
month = {2011/9/6},
abstract = { Motivated by ongoing measurements at JILA, we calculate the recoil-free
spectra of dipolar interacting fermions, for example ultracold heteronuclear
molecules, in a one-dimensional lattice of two-dimensional pancakes,
spectroscopically probing transitions between different internal (e.g.,
rotational) states. We additionally incorporate p-wave interactions and losses,
which are important for reactive molecules such as KRb. Moreover, we consider
other sources of spectral broadening: interaction-induced quasiparticle
lifetimes and the different polarizabilities of the different rotational states
used for the spectroscopy. Although our main focus is molecules, some of the
calculations are also useful for optical lattice atomic clocks. For example,
understanding the p-wave shifts between identical fermions and small dipolar
interactions coming from the excited clock state are necessary to reach future
precision goals. Finally, we consider the spectra in a deep 3D lattice and show
how they give a great deal of information about static correlation functions,
including \textit{all} the moments of the density correlations between nearby
sites. The range of correlations measurable depends on spectroscopic resolution
and the dipole moment.
},
doi = {10.1103/PhysRevA.84.033608},
url = {http://arxiv.org/abs/1106.1718v1},
author = {Kaden R. A. Hazzard and Alexey V. Gorshkov and Ana Maria Rey}
}