01204nas a2200181 4500008004100000245007100041210006900112260001500181490000800196520064500204100002700849700001900876700001900895700002700914700002000941700002500961856003600986 2018 eng d00aSpectrum estimation of density operators with alkaline-earth atoms0 aSpectrum estimation of density operators with alkalineearth atom c2018/01/090 v1203 aWe show that Ramsey spectroscopy of fermionic alkaline-earth atoms in a square-well trap provides an efficient and accurate estimate for the eigenspectrum of a density matrix whose *n *copies are stored in the nuclear spins of *n *such atoms. This spectrum estimation is enabled by the high symmetry of the interaction Hamiltonian, dictated, in turn, by the decoupling of the nuclear spin from the electrons and by the shape of the square-well trap. Practical performance of this procedure and its potential applications to quantum computing, quantum simulation, and time-keeping with alkalineearth atoms are discussed.

1 aBeverland, Michael, E.1 aHaah, Jeongwan1 aAlagic, Gorjan1 aCampbell, Gretchen, K.1 aRey, Ana, Maria1 aGorshkov, Alexey, V. uhttp://arxiv.org/abs/1608.0204509346nas a2200181 4500008004100000245005500041210005400096260001500150520881500165100001908980700001608999700002309015700002409038700002009062700002009082700002509102856003709127 2016 eng d00aSteady-state superradiance with Rydberg polaritons0 aSteadystate superradiance with Rydberg polaritons c2016/11/023 aA steady-state superradiant laser can be used to generate ultranarrow-linewidth light, and thus has important applications in the fields of quantum information and precision metrology. However, the light produced by such a laser is still essentially classical. Here, we show that the introduction of a Rydberg medium into a cavity containing atoms with a narrow optical transition can lead to the steady-state superradiant emission of ultranarrow-linewidth nonclassical light. The cavity nonlinearity induced by the Rydberg medium strongly modifies the superradiance threshold, and leads to a Mollow triplet in the cavity output spectrum−this behavior can be understood as an unusual analogue of resonance fluorescence. The cavity output spectrum has an extremely sharp central peak, with a linewidth that can be far narrower than that of a classical superradiant laser. This unprecedented spectral sharpness, together with the nonclassical nature of the light, could lead to new applications in which spectrally pure quantum light is desired.

1 aGong, Zhe-Xuan1 aXu, Minghui1 aFoss-Feig, Michael1 aThompson, James, K.1 aRey, Ana, Maria1 aHolland, Murray1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/1611.0079702029nas a2200241 4500008004100000245006600041210006500107260001400172490000800186520133800194100002601532700001801558700002301576700001201599700002201611700002101633700002001654700002301674700001201697700002101709700002001730856003701750 2014 eng d00aMany-body dynamics of dipolar molecules in an optical lattice0 aManybody dynamics of dipolar molecules in an optical lattice c2014/11/70 v1133 a 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.
1 aHazzard, Kaden, R. A.1 aGadway, Bryce1 aFoss-Feig, Michael1 aYan, Bo1 aMoses, Steven, A.1 aCovey, Jacob, P.1 aYao, Norman, Y.1 aLukin, Mikhail, D.1 aYe, Jun1 aJin, Deborah, S.1 aRey, Ana, Maria uhttp://arxiv.org/abs/1402.2354v101850nas a2200205 4500008004100000245008200041210006900123260001500192490000700207520120600214100002601420700002601446700002301472700002701495700002701522700001701549700002101566700002001587856003701607 2014 eng d00aQuantum correlations and entanglement in far-from-equilibrium spin systems
0 aQuantum correlations and entanglement in farfromequilibrium spin c2014/12/150 v903 a 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.
1 aHazzard, Kaden, R. A.1 avan den Worm, Mauritz1 aFoss-Feig, Michael1 aManmana, Salvatore, R.1 aTorre, Emanuele, Dalla1 aPfau, Tilman1 aKastner, Michael1 aRey, Ana, Maria uhttp://arxiv.org/abs/1406.0937v102020nas a2200265 4500008004100000245009000041210006900131260001400200490000800214520123900222100001501461700001801476700002301494700002801517700001801545700002601563700001201589700002201601700002101623700002101644700001201665700002001677700002001697856003701717 2014 eng d00aSuppressing the loss of ultracold molecules via the continuous quantum Zeno effect
0 aSuppressing the loss of ultracold molecules via the continuous q c2014/2/200 v1123 a 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.
1 aZhu, Bihui1 aGadway, Bryce1 aFoss-Feig, Michael1 aSchachenmayer, Johannes1 aWall, Michael1 aHazzard, Kaden, R. A.1 aYan, Bo1 aMoses, Steven, A.1 aCovey, Jacob, P.1 aJin, Deborah, S.1 aYe, Jun1 aHolland, Murray1 aRey, Ana, Maria uhttp://arxiv.org/abs/1310.2221v202138nas a2200181 4500008004100000245011400041210006900155260001500224300001100239490000700250520155000257100002301807700002401830700002301854700002001877700002201897856003701919 2013 eng d00aDynamical quantum correlations of Ising models on an arbitrary lattice and their resilience to decoherence
0 aDynamical quantum correlations of Ising models on an arbitrary l c2013/11/07 a1130080 v153 a Ising models, and the physical systems described by them, play a central role
in generating entangled states for use in quantum metrology and quantum
information. In particular, ultracold atomic gases, trapped ion systems, and
Rydberg atoms realize long-ranged Ising models, which even in the absence of a
transverse field can give rise to highly non-classical dynamics and long-range
quantum correlations. In the first part of this paper, we present a detailed
theoretical framework for studying the dynamics of such systems driven (at time
t=0) into arbitrary unentangled non-equilibrium states, thus greatly extending
and unifying the work of Ref. [1]. Specifically, we derive exact expressions
for closed-time-path ordered correlation functions, and use these to study
experimentally relevant observables, e.g. Bloch vector and spin-squeezing
dynamics. In the second part, these correlation functions are then used to
derive closed-form expressions for the dynamics of arbitrary spin-spin
correlation functions in the presence of both T_1 (spontaneous spin
relaxation/excitation) and T_2 (dephasing) type decoherence processes. Even
though the decoherence is local, our solution reveals that the competition
between Ising dynamics and T_1 decoherence gives rise to an emergent non-local
dephasing effect, thereby drastically amplifying the degradation of quantum
correlations. In addition to identifying the mechanism of this deleterious
effect, our solution points toward a scheme to eliminate it via
measurement-based coherent feedback.
1 aFoss-Feig, Michael1 aHazzard, Kaden, R A1 aBollinger, John, J1 aRey, Ana, Maria1 aClark, Charles, W uhttp://arxiv.org/abs/1306.0172v101291nas a2200157 4500008004100000245007400041210006900115260001400184490000800198520079400206100002601000700002701026700002301053700002001076856003701096 2013 eng d00aFar from equilibrium quantum magnetism with ultracold polar molecules0 aFar from equilibrium quantum magnetism with ultracold polar mole c2013/2/110 v1103 a 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.
1 aHazzard, Kaden, R. A.1 aManmana, Salvatore, R.1 aFoss-Feig, Michael1 aRey, Ana, Maria uhttp://arxiv.org/abs/1209.4076v101632nas a2200157 4500008004100000245007100041210006900112260001500181300001600196490000800212520114600220100002501366700002601391700002001417856003701437 2013 eng d00aKitaev honeycomb and other exotic spin models with polar molecules0 aKitaev honeycomb and other exotic spin models with polar molecul c2013/01/01 a1908 - 19160 v1113 a 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.
1 aGorshkov, Alexey, V.1 aHazzard, Kaden, R. A.1 aRey, Ana, Maria uhttp://arxiv.org/abs/1301.5636v101346nas a2200157 4500008004100000245008400041210006900125260001300194490000700207520084400214100002301058700002601081700002401107700002001131856003701151 2013 eng d00aNon-equilibrium dynamics of Ising models with decoherence: an exact solution
0 aNonequilibrium dynamics of Ising models with decoherence an exac c2013/4/30 v873 a 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.
1 aFoss-Feig, Michael1 aHazzard, Kaden, R. A.1 aBollinger, John, J.1 aRey, Ana, Maria uhttp://arxiv.org/abs/1209.5795v201446nas a2200169 4500008004100000245006700041210006600108260001400174490000700188520092200195100002701117700002401144700002601168700002001194700002501214856003701239 2013 eng d00aTopological phases in ultracold polar-molecule quantum magnets0 aTopological phases in ultracold polarmolecule quantum magnets c2013/2/260 v873 a 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.
1 aManmana, Salvatore, R.1 aStoudenmire, E., M.1 aHazzard, Kaden, R. A.1 aRey, Ana, Maria1 aGorshkov, Alexey, V. uhttp://arxiv.org/abs/1210.5518v201519nas a2200217 4500008004100000245008300041210006900124260001400193490000800207520087700215100002001092700002101112700002201133700001201155700002101167700002301188700002001211700002101231700001201252856003701264 2012 eng d00aLong-lived dipolar molecules and Feshbach molecules in a 3D optical lattice
0 aLonglived dipolar molecules and Feshbach molecules in a 3D optic c2012/2/230 v1083 a We have realized long-lived ground-state polar molecules in a 3D optical
lattice, with a lifetime of up to 25 s, which is limited only by off-resonant
scattering of the trapping light. Starting from a 2D optical lattice, we
observe that the lifetime increases dramatically as a small lattice potential
is added along the tube-shaped lattice traps. The 3D optical lattice also
dramatically increases the lifetime for weakly bound Feshbach molecules. For a
pure gas of Feshbach molecules, we observe a lifetime of >20 s in a 3D optical
lattice; this represents a 100-fold improvement over previous results. This
lifetime is also limited by off-resonant scattering, the rate of which is
related to the size of the Feshbach molecule. Individually trapped Feshbach
molecules in the 3D lattice can be converted to pairs of K and Rb atoms and
back with nearly 100% efficiency.
1 aChotia, Amodsen1 aNeyenhuis, Brian1 aMoses, Steven, A.1 aYan, Bo1 aCovey, Jacob, P.1 aFoss-Feig, Michael1 aRey, Ana, Maria1 aJin, Deborah, S.1 aYe, Jun uhttp://arxiv.org/abs/1110.4420v101233nas a2200157 4500008004100000245006500041210006300106260001400169490000800183520075800191100002300949700002200972700002400994700002001018856003701038 2012 eng d00aSteady-state many-body entanglement of hot reactive fermions0 aSteadystate manybody entanglement of hot reactive fermions c2012/12/40 v1093 a Entanglement is typically created via systematic intervention in the time
evolution of an initially unentangled state, which can be achieved by coherent
control, carefully tailored non-demolition measurements, or dissipation in the
presence of properly engineered reservoirs. In this paper we show that
two-component Fermi gases at ~\mu K temperatures naturally evolve, in the
presence of reactive two-body collisions, into states with highly entangled
(Dicke-type) spin wavefunctions. The entanglement is a steady-state property
that emerges---without any intervention---from uncorrelated initial states, and
could be used to improve the accuracy of spectroscopy in experiments with
fermionic alkaline earth atoms or fermionic groundstate molecules.
1 aFoss-Feig, Michael1 aDaley, Andrew, J.1 aThompson, James, K.1 aRey, Ana, Maria uhttp://arxiv.org/abs/1207.4741v101352nas a2200145 4500008004100000245007400041210006900115260001500184490000700199520089800206100002001104700002001124700002501144856003701169 2011 eng d00ad-Wave Superfluidity in Optical Lattices of Ultracold Polar Molecules0 adWave Superfluidity in Optical Lattices of Ultracold Polar Molec c2011/12/290 v843 a Recent work on ultracold polar molecules, governed by a generalization of the
t-J Hamiltonian, suggests that molecules may be better suited than atoms for
studying d-wave superfluidity due to stronger interactions and larger
tunability of the system. We compute the phase diagram for polar molecules in a
checkerboard lattice consisting of weakly coupled square plaquettes. In the
simplest experimentally realizable case where there is only tunneling and an
XX-type spin-spin interaction, we identify the parameter regime where d-wave
superfluidity occurs. We also find that the inclusion of a density-density
interaction destroys the superfluid phase and that the inclusion of a
spin-density or an Ising-type spin-spin interaction can enhance the superfluid
phase. We also propose schemes for experimentally realizing the perturbative
calculations exhibiting enhanced d-wave superfluidity.
1 aKuns, Kevin, A.1 aRey, Ana, Maria1 aGorshkov, Alexey, V. uhttp://arxiv.org/abs/1110.5330v201461nas a2200133 4500008004100000245005000041210004900091260001500140490000700155520108500162100002301247700002001270856003701290 2011 eng d00aPhase diagram of the Bose Kondo-Hubbard model0 aPhase diagram of the Bose KondoHubbard model c2011/11/160 v843 a We study a bosonic version of the Kondo lattice model with an on-site
repulsion in the conduction band, implemented with alkali atoms in two bands of
an optical lattice. Using both weak and strong-coupling perturbation theory, we
find that at unit filling of the conduction bosons the superfluid to Mott
insulator transition should be accompanied by a magnetic transition from a
ferromagnet (in the superfluid) to a paramagnet (in the Mott insulator).
Furthermore, an analytic treatment of Gutzwiller mean-field theory reveals that
quantum spin fluctuations induced by the Kondo exchange cause the otherwise
continuous superfluid to Mott-insulator phase transition to be first order. We
show that lattice separability imposes a serious constraint on proposals to
exploit excited bands for quantum simulations, and discuss a way to overcome
this constraint in the context of our model by using an experimentally realized
non-separable lattice. A method to probe the first-order nature of the
transition based on collapses and revivals of the matter-wave field is also
discussed.
1 aFoss-Feig, Michael1 aRey, Ana, Maria uhttp://arxiv.org/abs/1103.0245v201573nas a2200181 4500008004100000245004700041210004700088260001400135490000700149520106900156100002501225700002701250700001501277700001901292700002301311700002001334856003701354 2011 eng d00aQuantum Magnetism with Polar Alkali Dimers0 aQuantum Magnetism with Polar Alkali Dimers c2011/9/150 v843 a 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.
1 aGorshkov, Alexey, V.1 aManmana, Salvatore, R.1 aChen, Gang1 aDemler, Eugene1 aLukin, Mikhail, D.1 aRey, Ana, Maria uhttp://arxiv.org/abs/1106.1655v101287nas a2200181 4500008004100000245007300041210006900114260001400183490000800197520074600205100002000951700001400971700002600985700002501011700001201036700002001048856003701068 2011 eng d00aResolved atomic interaction sidebands in an optical clock transition0 aResolved atomic interaction sidebands in an optical clock transi c2011/6/220 v1063 a We report the observation of resolved atomic interaction sidebands (ISB) in
the ${}^{87}$Sr optical clock transition when atoms at microkelvin temperatures
are confined in a two-dimensional (2D) optical lattice. The ISB are a
manifestation of the strong interactions that occur between atoms confined in a
quasi-one-dimensional geometry and disappear when the confinement is relaxed
along one dimension. The emergence of ISB is linked to the recently observed
suppression of collisional frequency shifts in [1]. At the current
temperatures, the ISB can be resolved but are broad. At lower temperatures, ISB
are predicted to be substantially narrower and usable as powerful spectroscopic
tools in strongly interacting alkaline-earth gases.
1 aBishof, Michael1 aLin, Yige1 aSwallows, Matthew, D.1 aGorshkov, Alexey, V.1 aYe, Jun1 aRey, Ana, Maria uhttp://arxiv.org/abs/1102.1016v201707nas a2200145 4500008004100000245006800041210006800109260001300177490000700190520125600197100002601453700002501479700002001504856003701524 2011 eng d00aSpectroscopy of dipolar fermions in 2D pancakes and 3D lattices0 aSpectroscopy of dipolar fermions in 2D pancakes and 3D lattices c2011/9/60 v843 a 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.
1 aHazzard, Kaden, R. A.1 aGorshkov, Alexey, V.1 aRey, Ana, Maria uhttp://arxiv.org/abs/1106.1718v101551nas a2200193 4500008004100000245008200041210006900123260001300192490000800205520096600213100002501179700002701204700001501231700001201246700001901258700002301277700002001300856003701320 2011 eng d00aTunable Superfluidity and Quantum Magnetism with Ultracold Polar Molecules
0 aTunable Superfluidity and Quantum Magnetism with Ultracold Polar c2011/9/80 v1073 a 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.
1 aGorshkov, Alexey, V.1 aManmana, Salvatore, R.1 aChen, Gang1 aYe, Jun1 aDemler, Eugene1 aLukin, Mikhail, D.1 aRey, Ana, Maria uhttp://arxiv.org/abs/1106.1644v101646nas a2200157 4500008004100000245004100041210004100082260001500123490000700138520122200145100002301367700002101390700002001411700002001431856003701451 2010 eng d00aHeavy fermions in an optical lattice0 aHeavy fermions in an optical lattice c2010/11/220 v823 a We employ a mean-field theory to study ground-state properties and transport
of a two-dimensional gas of ultracold alklaline-earth metal atoms governed by
the Kondo Lattice Hamiltonian plus a parabolic confining potential. In a
homogenous system this mean-field theory is believed to give a qualitatively
correct description of heavy fermion metals and Kondo insulators: it reproduces
the Kondo-like scaling of the quasiparticle mass in the former, and the same
scaling of the excitation gap in the latter. In order to understand
ground-state properties in a trap we extend this mean-field theory via
local-density approximation. We find that the Kondo insulator gap manifests as
a shell structure in the trapped density profile. In addition, a strong
signature of the large Fermi surface expected for heavy fermion systems
survives the confinement, and could be probed in time-of-flight experiments.
From a full self-consistent diagonalization of the mean-field theory we are
able to study dynamics in the trap. We find that the mass enhancement of
quasiparticle excitations in the heavy Fermi liquid phase manifests as slowing
of the dipole oscillations that result from a sudden displacement of the trap
center.
1 aFoss-Feig, Michael1 aHermele, Michael1 aGurarie, Victor1 aRey, Ana, Maria uhttp://arxiv.org/abs/1007.5083v100925nas a2200145 4500008004100000245006200041210006200103260001300165490000700178520049300185100002300678700002100701700002000722856003700742 2010 eng d00aProbing the Kondo Lattice Model with Alkaline Earth Atoms0 aProbing the Kondo Lattice Model with Alkaline Earth Atoms c2010/5/70 v813 a We study transport properties of alkaline-earth atoms governed by the Kondo
Lattice Hamiltonian plus a harmonic confining potential, and suggest simple
dynamical probes of several different regimes of the phase diagram that can be
implemented with current experimental techniques. In particular, we show how
Kondo physics at strong coupling, low density, and in the heavy fermion phase
is manifest in the dipole oscillations of the conduction band upon displacement
of the trap center.
1 aFoss-Feig, Michael1 aHermele, Michael1 aRey, Ana, Maria uhttp://arxiv.org/abs/0912.4762v101223nas a2200193 4500008004100000245006200041210005900103260001400162490000800176520066700184100002500851700002000876700002200896700002100918700001200939700001800951700002300969856003700992 2009 eng d00aAlkaline-Earth-Metal Atoms as Few-Qubit Quantum Registers0 aAlkalineEarthMetal Atoms as FewQubit Quantum Registers c2009/3/180 v1023 a We propose and analyze a novel approach to quantum information processing, in
which multiple qubits can be encoded and manipulated using electronic and
nuclear degrees of freedom associated with individual alkaline-earth atoms
trapped in an optical lattice. Specifically, we describe how the qubits within
each register can be individually manipulated and measured with sub-wavelength
optical resolution. We also show how such few-qubit registers can be coupled to
each other in optical superlattices via conditional tunneling to form a
scalable quantum network. Finally, potential applications to quantum
computation and precision measurements are discussed.
1 aGorshkov, Alexey, V.1 aRey, Ana, Maria1 aDaley, Andrew, J.1 aBoyd, Martin, M.1 aYe, Jun1 aZoller, Peter1 aLukin, Mikhail, D. uhttp://arxiv.org/abs/0812.3660v201812nas a2200169 4500008004100000245010200041210006900143260001300212490000700225520125500232100002601487700002001513700001901533700002301552700002301575856004401598 2006 eng d00aMean-field treatment of the damping of the oscillations of a 1D Bose gas in an optical lattice
0 aMeanfield treatment of the damping of the oscillations of a 1D B c2006/1/90 v733 a We present a theoretical treatment of the surprisingly large damping observed
recently in one-dimensional Bose-Einstein atomic condensates in optical
lattices. We show that time-dependent Hartree-Fock-Bogoliubov (HFB)
calculations can describe qualitatively the main features of the damping
observed over a range of lattice depths. We also derive a formula of the
fluctuation-dissipation type for the damping, based on a picture in which the
coherent motion of the condensate atoms is disrupted as they try to flow
through the random local potential created by the irregular motion of
noncondensate atoms. We expect this irregular motion to result from the
well-known dynamical instability exhibited by the mean-field theory for these
systems. When parameters for the characteristic strength and correlation times
of the fluctuations, obtained from the HFB calculations, are substituted in the
damping formula, we find very good agreement with the experimentally-observed
damping, as long as the lattice is shallow enough for the fraction of atoms in
the Mott insulator phase to be negligible. We also include, for completeness,
the results of other calculations based on the Gutzwiller ansatz, which appear
to work better for the deeper lattices.
1 aGea-Banacloche, Julio1 aRey, Ana, Maria1 aPupillo, Guido1 aWilliams, Carl, J.1 aClark, Charles, W. uhttp://arxiv.org/abs/cond-mat/0410677v401217nas a2200169 4500008004100000245006000041210005800101260001500159300001400174490000600188520072400194100001900918700002000937700002300957700002300980856004401003 2006 eng d00aPseudo-fermionization of 1-D bosons in optical lattices0 aPseudofermionization of 1D bosons in optical lattices c2006/08/30 a161 - 1610 v83 a We present a model that generalizes the Bose-Fermi mapping for strongly
correlated 1D bosons in an optical lattice, to cases in which the average
number of atoms per site is larger than one. This model gives an accurate
account of equilibrium properties of such systems, in parameter regimes
relevant to current experiments. The application of this model to
non-equilibrium phenomena is explored by a study of the dynamics of an atom
cloud subject to a sudden displacement of the confining potential. Good
agreement is found with results of recent experiments. The simplicity and
intuitive appeal of this model make it attractive as a general tool for
understanding bosonic systems in the strongly correlated regime.
1 aPupillo, Guido1 aRey, Ana, Maria1 aWilliams, Carl, J.1 aClark, Charles, W. uhttp://arxiv.org/abs/cond-mat/0505325v201431nas a2200169 4500008004100000245007100041210006900112260001400181490000700195520091200202100002001114700001801134700001901152700002301171700002301194856004401217 2005 eng d00aBragg Spectroscopy of ultracold atoms loaded in an optical lattice0 aBragg Spectroscopy of ultracold atoms loaded in an optical latti c2005/8/120 v723 a We study Bragg spectroscopy of ultra-cold atoms in one-dimensional optical
lattices as a method for probing the excitation spectrum in the Mott insulator
phase, in particular the one particle-hole excitation band. Within the
framework of perturbation theory we obtain an analytical expression for the
dynamic structure factor $S(q,\omega)$ and use it to calculate the imparted
energy which has shown to be a relevant observable in recent experiments. We
test the accuracy of our approximations by comparing them with numerically
exact solutions of the Bose-Hubbard model in restricted cases and establish the
limits of validity of our linear response analysis. Finally we show that when
the system is deep in the Mott insulator regime, its response to the Bragg
perturbation is temperature dependent. We suggest that this dependence might be
used as a tool to probe temperatures of order of the Mott gap.
1 aRey, Ana, Maria1 aBlakie, Blair1 aPupillo, Guido1 aWilliams, Carl, J.1 aClark, Charles, W. uhttp://arxiv.org/abs/cond-mat/0406552v201428nas a2200181 4500008004100000245008400041210006900125260001500194300001600209490000700225520086200232100002301094700001901117700002001136700002301156700002301179856004401202 2005 eng d00aScalable register initialization for quantum computing in an optical lattice
0 aScalable register initialization for quantum computing in an opt c2005/06/14 a1687 - 16940 v383 a The Mott insulator state created by loading an atomic Bose-Einstein
condensate (BEC) into an optical lattice may be used as a means to prepare a
register of atomic qubits in a quantum computer. Such architecture requires a
lattice commensurately filled with atoms, which corresponds to the insulator
state only in the limit of zero inter-well tunneling. We show that a lattice
with spatial inhomogeneity created by a quadratic magnetic trapping potential
can be used to isolate a subspace in the center which is impervious to
hole-hoping. Components of the wavefunction with more than one atom in any well
can be projected out by selective measurement on a molecular photo-associative
transition. Maintaining the molecular coupling induces a quantum Zeno effect
that can sustain a commensurately filled register for the duration of a quantum
computation.
1 aBrennen, Gavin, K.1 aPupillo, Guido1 aRey, Ana, Maria1 aClark, Charles, W.1 aWilliams, Carl, J. uhttp://arxiv.org/abs/quant-ph/0312069v101494nas a2200157 4500008004100000245010300041210006900144260001400213490000700227520097300234100002001207700001901227700002301246700002301269856004401292 2005 eng d00aUltracold atoms confined in an optical lattice plus parabolic potential: a closed-form approach
0 aUltracold atoms confined in an optical lattice plus parabolic po c2005/9/220 v723 a We discuss interacting and non-interacting one dimensional atomic systems
trapped in an optical lattice plus a parabolic potential. We show that, in the
tight-binding approximation, the non-interacting problem is exactly solvable in
terms of Mathieu functions. We use the analytic solutions to study the
collective oscillations of ideal bosonic and fermionic ensembles induced by
small displacements of the parabolic potential. We treat the interacting boson
problem by numerical diagonalization of the Bose-Hubbard Hamiltonian. From
analysis of the dependence upon lattice depth of the low-energy excitation
spectrum of the interacting system, we consider the problems of
"fermionization" of a Bose gas, and the superfluid-Mott insulator transition.
The spectrum of the noninteracting system turns out to provide a useful guide
to understanding the collective oscillations of the interacting system,
throughout a large and experimentally relevant parameter regime.
1 aRey, Ana, Maria1 aPupillo, Guido1 aClark, Charles, W.1 aWilliams, Carl, J. uhttp://arxiv.org/abs/cond-mat/0503477v201546nas a2200181 4500008004100000245007100041210006900112260001500181300001600196490000700212520099700219100001901216700002001235700001901255700002301274700002301297856004401320 2004 eng d00aScalable quantum computation in systems with Bose-Hubbard dynamics0 aScalable quantum computation in systems with BoseHubbard dynamic c2004/02/15 a2395 - 24040 v513 a Several proposals for quantum computation utilize a lattice type architecture
with qubits trapped by a periodic potential. For systems undergoing many body
interactions described by the Bose-Hubbard Hamiltonian, the ground state of the
system carries number fluctuations that scale with the number of qubits. This
process degrades the initialization of the quantum computer register and can
introduce errors during error correction. In an earlier manuscript we proposed
a solution to this problem tailored to the loading of cold atoms into an
optical lattice via the Mott Insulator phase transition. It was shown that by
adding an inhomogeneity to the lattice and performing a continuous measurement,
the unit filled state suitable for a quantum computer register can be
maintained. Here, we give a more rigorous derivation of the register fidelity
in homogeneous and inhomogeneous lattices and provide evidence that the
protocol is effective in the finite temperature regime.
1 aPupillo, Guido1 aRey, Ana, Maria1 aBrennen, Gavin1 aWilliams, Carl, J.1 aClark, Charles, W. uhttp://arxiv.org/abs/quant-ph/0403052v201370nas a2200193 4500008004100000245007200041210006900113260001500182300001400197490000700211520079400218100002001012700001901032700001701051700001801068700002301086700002301109856004401132 2003 eng d00aBogoliubov approach to superfluidity of atoms in an optical lattice0 aBogoliubov approach to superfluidity of atoms in an optical latt c2003/03/14 a825 - 8410 v363 a 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.
1 aRey, Ana, Maria1 aBurnett, Keith1 aRoth, Robert1 aEdwards, Mark1 aWilliams, Carl, J.1 aClark, Charles, W. uhttp://arxiv.org/abs/cond-mat/0210550v2