Multicomponent systems of ultracold atoms Eugene Demler Harvard University Dynamical instability of spiral states In collaboration with Robert Cherng,

Slides:

Advertisements

Similar presentations

Competing instabilities in ultracold Fermi gases $$ NSF, AFOSR MURI, DARPA ARO Harvard-MIT David Pekker (Harvard), Mehrtash Babadi (Harvard), Lode Pollet.

Advertisements

Learning about order from noise Quantum noise studies of ultracold atoms Eugene Demler Harvard University Funded by NSF, Harvard-MIT CUA, AFOSR, DARPA,

Superfluid insulator transition in a moving condensate Anatoli Polkovnikov Harvard University Ehud Altman, Eugene Demler, Bertrand Halperin, Misha Lukin.

Interference of one dimensional condensates Experiments: Schmiedmayer et al., Nature Physics (2005,2006) Transverse imaging long. imaging trans. imaging.

Magnetism in systems of ultracold atoms: New problems of quantum many-body dynamics E. Altman (Weizmann), P. Barmettler (Frieburg), V. Gritsev (Harvard,

Nonequilibrium dynamics of ultracold atoms in optical lattices. Lattice modulation experiments and more Ehud Altman Weizmann Institute Peter Barmettler.

Nonequilibrium dynamics of ultracold fermions Theoretical work: Mehrtash Babadi, David Pekker, Rajdeep Sensarma, Ehud Altman, Eugene Demler $$ NSF, MURI,

Eugene Demler Harvard University

Lattice modulation experiments with fermions in optical lattice Dynamics of Hubbard model Ehud Altman Weizmann Institute David Pekker Harvard University.

Condensed Matter models for many-body systems of ultracold atoms Eugene Demler Harvard University Collaborators: Ehud Altman, Robert Cherng, Adilet Imambekov,

Quantum dynamics in low dimensional systems. Anatoli Polkovnikov, Boston University AFOSR Superconductivity and Superfluidity in Finite Systems, U of Wisconsin,

Hubbard model(s) Eugene Demler Harvard University Collaboration with

Interference experiments with ultracold atoms Collaborators: Ehud Altman, Anton Burkov, Robert Cherng, Adilet Imambekov, Serena Fagnocchi, Vladimir Gritsev,

Breakdown of the adiabatic approximation in low-dimensional gapless systems Anatoli Polkovnikov, Boston University Vladimir Gritsev Harvard University.

Nonequilibrium spin dynamics in systems of ultracold atoms Funded by NSF, DARPA, MURI, AFOSR, Harvard-MIT CUA Collaborators: Ehud Altman, Robert Cherng,

World of zero temperature --- introduction to systems of ultracold atoms National Tsing-Hua University Daw-Wei Wang.

Magnetism in ultracold Fermi gases and New physics with ultracold ions: many-body systems with non-equilibrium noise $$ NSF, AFOSR MURI, DARPA Harvard-MIT.

Measuring correlation functions in interacting systems of cold atoms Anatoli Polkovnikov Boston University Ehud Altman Weizmann Vladimir Gritsev Harvard.

Competing instabilities in ultracold Fermi gases $$ NSF, AFOSR MURI, DARPA ARO Harvard-MIT David Pekker (Harvard) Mehrtash Babadi (Harvard) Lode Pollet.

Spinor condensates beyond mean-field

Quantum noise studies of ultracold atoms Eugene Demler Harvard University Funded by NSF, Harvard-MIT CUA, AFOSR, DARPA, MURI Collaborators: Ehud Altman,

E. Altman (Weizmann), P. Barmettler (Frieburg), V. Gritsev (Harvard, Freiburg), E. Dalla Torre (Weizmann), T. Giamarchi (Geneva), M. Lukin (Harvard), A.Polkovnikov.

Competing instabilities in ultracold Fermi gases $$ NSF, AFOSR MURI, DARPA Motivated by experiments of G.-B. Jo et al., Science (2009) Harvard-MIT David.

Strongly Correlated Systems of Ultracold Atoms Theory work at CUA.

Eugene Demler Harvard University Collaborators:

Fractional Quantum Hall states in optical lattices Anders Sorensen Ehud Altman Mikhail Lukin Eugene Demler Physics Department, Harvard University.

Quantum Simulation MURI Review Theoretical work by groups lead by Luming Duan (Michigan) Mikhail Lukin (Harvard) Subir Sachdev (Harvard) Peter Zoller (Innsbruck)

Measuring correlation functions in interacting systems of cold atoms

Superfluid insulator transition in a moving condensate Anatoli Polkovnikov Harvard University Ehud Altman, Eugene Demler, Bertrand Halperin, Misha Lukin.

Dipolar interactions and magnetoroton softening in spinor condensates Funded by NSF, DARPA, MURI, AFOSR, Harvard-MIT CUA Collaborators: Vladimir Gritsev.

Quantum simulator theory

Quantum dynamics in low dimensional isolated systems. Anatoli Polkovnikov, Boston University AFOSR Condensed Matter Colloquium, 04/03/2008 Roman Barankov.

Eugene Demler Harvard University Robert Cherng, Adilet Imambekov,

Nonequilibrium dynamics of ultracold atoms in optical lattices

Probing interacting systems of cold atoms using interference experiments Harvard-MIT CUA Vladimir Gritsev Harvard Adilet Imambekov Harvard Anton Burkov.

Probing many-body systems of ultracold atoms E. Altman (Weizmann), A. Aspect (CNRS, Paris), M. Greiner (Harvard), V. Gritsev (Freiburg), S. Hofferberth.

Strongly correlated systems: from electronic materials to cold atoms Collaborators: E. Altman, R. Barnett, I. Cirac, L. Duan, V. Gritsev, W. Hofstetter,

Quantum dynamics in low dimensional isolated systems. Anatoli Polkovnikov, Boston University AFOSR Joint Atomic Physics Colloquium, 02/27/2008 Roman Barankov.

Non-equilibrium dynamics of cold atoms in optical lattices Vladimir Gritsev Harvard Anatoli Polkovnikov Harvard/Boston University Ehud Altman Harvard/Weizmann.

Learning about order from noise Quantum noise studies of ultracold atoms Eugene Demler Harvard University Collaborators: Takuya Kitagawa, Susanne Pielawa,

Nonequilibrium dynamics of ultracold atoms in optical lattices. Lattice modulation experiments and more Ehud Altman Weizmann Institute Peter Barmettler.

Nonequilibrium dynamics of bosons in optical lattices $$ NSF, AFOSR MURI, DARPA, RFBR Harvard-MIT Eugene Demler Harvard University.

Vladimir Gritsev Harvard Adilet Imambekov Harvard Anton Burkov Harvard Robert Cherng Harvard Anatoli Polkovnikov Harvard/Boston University Ehud Altman.

Dipolar interactions in F=1 ferromagnetic spinor condensates. Roton instabilities and possible supersolid phase Eugene Demler Harvard University Funded.

Learning about order from noise Quantum noise studies of ultracold atoms Eugene Demler Harvard University Collaborators: Takuya Kitagawa, Susanne Pielawa,

Nonequilibrium dynamics of interacting systems of cold atoms Collaborators: Ehud Altman, Anton Burkov, Robert Cherng, Adilet Imambekov, Vladimir Gritsev,

Magnetism of spinor BEC in an optical lattice

Nonequilibrium dynamics of ultracold atoms in optical lattices David Pekker, Rajdeep Sensarma, Takuya Kitagawa, Susanne Pielawa, Vladmir Gritsev, Mikhail.

The Center for Ultracold Atoms at MIT and Harvard Quantum noise as probe of many-body systems Advisory Committee Visit, May 13-14, 2010.

Pairing and magnetism near Feshbach resonance $$ NSF, AFOSR MURI, DARPA, ARO Harvard-MIT David Pekker (Harvard/Caltech) Mehrtash Babadi (Harvard) Lode.

Interference of fluctuating condensates Anatoli Polkovnikov Harvard/Boston University Ehud Altman Harvard/Weizmann Vladimir Gritsev Harvard Mikhail Lukin.

Outline of these lectures Introduction. Systems of ultracold atoms. Cold atoms in optical lattices. Bose Hubbard model. Equilibrium and dynamics Bose mixtures.

T. Kitagawa (Harvard), S. Pielawa (Harvard), D. Pekker (Harvard), R. Sensarma (Harvard/JQI), V. Gritsev (Fribourg), M. Lukin (Harvard), Lode Pollet (Harvard)

Dynamics of repulsively bound pairs in fermionic Hubbard model David Pekker, Harvard University Rajdeep Sensarma, Harvard University Ehud Altman, Weizmann.

New physics with polar molecules Eugene Demler Harvard University Outline: Measurements of molecular wavefunctions using noise correlations Quantum critical.

University of Trento INFM. BOSE-EINSTEIN CONDENSATION IN TRENTO SUPERFLUIDITY IN TRAPPED GASES University of Trento Inauguration meeting, Trento

Eugene Demler Harvard University

Many-body quench dynamics in ultracold atoms Surprising applications to recent experiments $$ NSF, AFOSR MURI, DARPA Harvard-MIT Eugene Demler (Harvard)

Measuring correlation functions in interacting systems of cold atoms Anatoli Polkovnikov Harvard/Boston University Ehud Altman Harvard/Weizmann Vladimir.

Atoms in optical lattices and the Quantum Hall effect Anders S. Sørensen Niels Bohr Institute, Copenhagen.

Optical lattice emulator Strongly correlated systems: from electronic materials to ultracold atoms.

Quantum magnetism of ultracold atoms $$ NSF, AFOSR MURI, DARPA Harvard-MIT Theory collaborators: Robert Cherng, Adilet Imambekov, Vladimir Gritsev, Takuya.

The Center for Ultracold Atoms at MIT and Harvard Strongly Correlated Many-Body Systems Theoretical work in the CUA Advisory Committee Visit, May 13-14,

Exploring many-body physics with synthetic matter

Precision collective excitation measurements in the BEC-BCS crossover regime 15/06/2005, Strong correlations in Fermi systems A. Altmeyer 1, S. Riedl 12,

Probing interacting systems of cold atoms using interference experiments Vladimir Gritsev, Adilet Imambekov, Anton Burkov, Robert Cherng, Anatoli Polkovnikov,

Analysis of quantum noise

Ehud Altman Anatoli Polkovnikov Bertrand Halperin Mikhail Lukin

Part II New challenges in quantum many-body theory:

Dynamics of spinor condensates: dipolar interactions and more

Presentation transcript:

Multicomponent systems of ultracold atoms Eugene Demler Harvard University Dynamical instability of spiral states In collaboration with Robert Cherng, Vladimir Gritsev. Thanks to Dan Stamper-Kurn Many-body decoherence of Ramsey interference In collaboration with Artur Widera, Stefan Trotzky, Patrick Chainet, Fabrice Gerbier, Simon Folling, Immanuel Bloch (Mainz), Vladimir Gritsev, Mikhail Lukin Bose-Fermi mixtures in optical lattices In collaboration with Gil Refael (Caltech) Funded by NSF, MURI, AFOSR, Harvard-MIT CUA

Dynamical Instability of the Spiral State of F=1 Ferromagnetic Condensate Connections to spintronics in electron systems

Ferromagnetic spin textures created by D. Stamper-Kurn et al.

F=1 condensates Spinor order parameter Vector representation Ferromagnetic State Polar (nematic) state Ferromagnetic state realized for g s > 0

Spiral Ferromagnetic State of F=1 condensate Gross-Pitaevski equation Mean-field spiral state The nature of the mean-field state depends on the system preparation. Sudden twisting Instabillities can be obtained from the analysis of collective modes Adiabatic limit: q determined from the condition of the stationary state.

Collective modes

Instabilities of the spiral state Adiabatic limitSudden limit

Mean-field energy Inflection point suggests instability Uniform spiral Non-uniform spiral Negative value of shows that the system can lower its energy by making a non-uniform spiral winding

Instabilities of the spiral state Adiabatic limitSudden limit Beyond mean-field: thermal and quantum phase slips?

Many-body decoherence and Ramsey interferometry Connections to one dimensional electron systems. New feature: application of Luttinger liquid model for describing non-equilibrium dynamics

Working with N atoms improves the precision by. Need spin squeezed states to improve frequency spectroscopy Ramsey interference t 0 1

Squeezed spin states for spectroscopy Generation of spin squeezing using interactions. Two component BEC. Single mode approximation Motivation: improved spectroscopy, e.g. Wineland et. al. PRA 50:67 (1994) Kitagawa, Ueda, PRA 47:5138 (1993) In the single mode approximation we can neglect kinetic energy terms

Interaction induced collapse of Ramsey fringes Experiments in 1d tubes: A. Widera, I. Bloch et al. time Ramsey fringe visibility - volume of the system

Spin echo. Time reversal experiments Single mode approximation Predicts perfect spin echo The Hamiltonian can be reversed by changing a 12

Spin echo. Time reversal experiments No revival? Expts: A. Widera, I. Bloch et al. Experiments done in array of tubes. Strong fluctuations in 1d systems. Single mode approximation does not apply. Need to analyze the full model

Interaction induced collapse of Ramsey fringes. Multimode analysis Luttinger model Changing the sign of the interaction reverses the interaction part of the Hamiltonian but not the kinetic energy Time dependent harmonic oscillators can be analyzed exactly Low energy effective theory: Luttinger liquid approach

Time-dependent harmonic oscillator Explicit quantum mechanical wavefunction can be found From the solution of classical problem We solve this problem for each momentum component See e.g. Lewis, Riesengeld (1969) Malkin, Man’ko (1970)

Interaction induced collapse of Ramsey fringes in one dimensional systems Fundamental limit on Ramsey interferometry Only q=0 mode shows complete spin echo Finite q modes continue decay The net visibility is a result of competition between q=0 and other modes Conceptually similar to experiments with dynamics of split condensates. T. Schumm’s talk

Boson Fermion mixtures Connections to polaronic effects in electron-phonon systems. New feature: quantum regime of bosons

Boson Fermion mixtures BEC Experiments: ENS, Florence, JILA, MIT, ETH, Hamburg, Rice, Duke, Mainz, … Bosons provide cooling for fermions and mediate interactions. They create non-local attraction between fermions Charge Density Wave Phase Periodic arrangement of atoms Non-local Fermion Pairing P-wave, D-wave, … Theory: Pu, Illuminati, Efremov, Das, Wang, Matera, Lewenstein, Buchler, …

Boson Fermion mixtures “Phonons” : Bogoliubov (phase) mode Effective fermion-”phonon” interaction Fermion-”phonon” vertex Similar to electron-phonon systems

Suppression of superfluidity of bosons by fermions Similar observation for Bose-Bose mixtures, see Catani et al., arXiv: Bose-Fermi mixture in a three dimensional optical lattice Gunter et al, PRL 96: (2006) See also Ospelkaus et al, PRL 96: (2006) Issue of heating needs to be sorted out, see e.g. Pollet et al., cond-mat/

Orthogonality catastrophy due to fermions. Polaronic dressing of bosons. Favors Mott insulating state of bosons Fermions Bosons Fermions Competing effects of fermions on bosons Fermions provide screening. Favors superfluid state of bosons

Quantum regime of bosons A better starting point: Mott insulating state of bosons Free Fermi sea Theoretical approach: generalized Weiss theory

Weiss theory of magnetism Heisenberg model Mean field: a single spin in a self-consistent field

Weiss theory of the superfluid to Mott transition of bosons in an optical lattice Mean-field: a single site in a self-consistent field

Weiss theory: quantum action O(2) rotor: Conjugate variables SF-Mott transition: expansion for small r Self-consistency condition

Adding fermions Screening Orthogonality catastrophy X-Ray edge singularity: Roule, Gavoret, Nozieres (1969) Ohmic dissipation: Caldeira, Leggett (1983) Fermions Bosons Fermions

SF-Mott transition in the presence of fermions Competition of screening and orthogonality catastrophy Effect of fast fermions t F /U=5Effect of slow fermions t F /U=0.7

Summary Dynamical instability of spiral states In collaboration with Robert Cherng, Vladimir Gritsev. Thanks to Dan Stamper-Kurn Many-body decoherence of Ramsey interference In collaboration with Artur Widera, Stefan Trotzky, Patrick Chainet, Fabrice Gerbier, Simon Folling, Immanuel Bloch (Mainz), Vladimir Gritsev, Mikhail Lukin Bose-Fermi mixtures in optical lattices In collaboration with Gil Refael (Caltech)