%0 Journal Article
%J Physical Review Letters
%D 2014
%T Many-body dynamics of dipolar molecules in an optical lattice
%A Kaden R. A. Hazzard
%A Bryce Gadway
%A Michael Foss-Feig
%A Bo Yan
%A Steven A. Moses
%A Jacob P. Covey
%A Norman Y. Yao
%A Mikhail D. Lukin
%A Jun Ye
%A Deborah S. Jin
%A Ana Maria Rey
%X 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.
%B Physical Review Letters
%V 113
%8 2014/11/7
%G eng
%U http://arxiv.org/abs/1402.2354v1
%N 19
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.113.195302
%0 Journal Article
%J Physical Review A
%D 2014
%T Quantum correlations and entanglement in far-from-equilibrium spin systems
%A Kaden R. A. Hazzard
%A Mauritz van den Worm
%A Michael Foss-Feig
%A Salvatore R. Manmana
%A Emanuele Dalla Torre
%A Tilman Pfau
%A Michael Kastner
%A Ana Maria Rey
%X 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.
%B Physical Review A
%V 90
%8 2014/12/15
%G eng
%U http://arxiv.org/abs/1406.0937v1
%N 6
%! Phys. Rev. A
%R 10.1103/PhysRevA.90.063622
%0 Journal Article
%J Physical Review Letters
%D 2014
%T Suppressing the loss of ultracold molecules via the continuous quantum Zeno effect
%A Bihui Zhu
%A Bryce Gadway
%A Michael Foss-Feig
%A Johannes Schachenmayer
%A Michael Wall
%A Kaden R. A. Hazzard
%A Bo Yan
%A Steven A. Moses
%A Jacob P. Covey
%A Deborah S. Jin
%A Jun Ye
%A Murray Holland
%A Ana Maria Rey
%X 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.
%B Physical Review Letters
%V 112
%8 2014/2/20
%G eng
%U http://arxiv.org/abs/1310.2221v2
%N 7
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.112.070404
%0 Journal Article
%J Physical Review Letters
%D 2013
%T Far from equilibrium quantum magnetism with ultracold polar molecules
%A Kaden R. A. Hazzard
%A Salvatore R. Manmana
%A Michael Foss-Feig
%A Ana Maria Rey
%X 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.
%B Physical Review Letters
%V 110
%8 2013/2/11
%G eng
%U http://arxiv.org/abs/1209.4076v1
%N 7
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.110.075301
%0 Journal Article
%J Molecular Physics
%D 2013
%T Kitaev honeycomb and other exotic spin models with polar molecules
%A Alexey V. Gorshkov
%A Kaden R. A. Hazzard
%A Ana Maria Rey
%X 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.
%B Molecular Physics
%V 111
%P 1908 - 1916
%8 2013/01/01
%G eng
%U http://arxiv.org/abs/1301.5636v1
%N 12-13
%! Molecular Physics
%R 10.1080/00268976.2013.800604
%0 Journal Article
%J Physical Review A
%D 2013
%T Non-equilibrium dynamics of Ising models with decoherence: an exact solution
%A Michael Foss-Feig
%A Kaden R. A. Hazzard
%A John J. Bollinger
%A Ana Maria Rey
%X 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.
%B Physical Review A
%V 87
%8 2013/4/3
%G eng
%U http://arxiv.org/abs/1209.5795v2
%N 4
%! Phys. Rev. A
%R 10.1103/PhysRevA.87.042101
%0 Journal Article
%J Physical Review B
%D 2013
%T Topological phases in ultracold polar-molecule quantum magnets
%A Salvatore R. Manmana
%A E. M. Stoudenmire
%A Kaden R. A. Hazzard
%A Ana Maria Rey
%A Alexey V. Gorshkov
%X 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.
%B Physical Review B
%V 87
%8 2013/2/26
%G eng
%U http://arxiv.org/abs/1210.5518v2
%N 8
%! Phys. Rev. B
%R 10.1103/PhysRevB.87.081106
%0 Journal Article
%J Physical Review A
%D 2011
%T Spectroscopy of dipolar fermions in 2D pancakes and 3D lattices
%A Kaden R. A. Hazzard
%A Alexey V. Gorshkov
%A Ana Maria Rey
%X 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.
%B Physical Review A
%V 84
%8 2011/9/6
%G eng
%U http://arxiv.org/abs/1106.1718v1
%N 3
%! Phys. Rev. A
%R 10.1103/PhysRevA.84.033608