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Hanns-Christoph Nägerl Institut für Experimentalphysik , Universität Innsbruck

Firenze, May 21 st 2012: New quantum states of matter in and out of equilibrium. 1700 m. Atoms with tunable interactions in optical lattice confinement. Hanns-Christoph Nägerl Institut für Experimentalphysik , Universität Innsbruck. CsIII -Project Team Members & Collaborators….

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Hanns-Christoph Nägerl Institut für Experimentalphysik , Universität Innsbruck

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  1. Firenze, May 21st 2012: New quantum states of matter in and out of equilibrium 1700 m Atoms with tunable interactions in optical lattice confinement Hanns-Christoph Nägerl InstitutfürExperimentalphysik, Universität Innsbruck

  2. CsIII-Project Team Members & Collaborators… new phd and master students: B. Rutschmann Florian Meinert Philipp Meinmann Nobie Redmon Michael Gröbner Elmar Haller (nowto Glasgow) Johann Danzl (nowto Göttingen) theory support (Strasbourg/Innsbruck/Pittsburgh): Guido Pupillo / Marcello Dalmonte / Andrew Daley Manfred Mark collaborators: P. Schmelcher (Hamburg) V. Melezhik (Dubna) H. Ritsch (Innsbruck) N. Bouloufa (Orsay) O. Dulieu (Orsay) T. Bergeman (Stony Brook) H.-P. Büchler (Stuttgart) J. Aldegunde (Durham) J. Hutson (Durham) P. S. Julienne (NIST) Katharina Lauber CsIII-Team

  3. Motivation: Bosons in lattices and confined dimensions Bose-Hubbard Physics • U<0 and U=U(n) n = particlenumberatthelatticesites

  4. E twoatoms molecule B Feshbach resonance • Tuning of interactions: Feshbach resonances scatteringlengthaS= aS(B) aS abg ¢ = coupling B0 B

  5. this talk… (let’s zoom in) • Tuning of interactions: Feshbach resonances scattering length for 2 atoms in hyperfine states (F,mF)= (3,3) broad s-resonances 10 calculations by P. Julienne et al., NIST s s 5 scattering length aS (1000 a0) 0 -5 -10 magnetic field B (Gauss)

  6. g d g g d g d …or here zero crossing make BEC here make mol’s here… • Tuning of interactions: Feshbach resonances scattering length for 2 atoms in hyperfine states (F,mF)= (3,3) narrower d-resonances verynarrow g-resonances g 2 tune here 1 0 scattering length aS (1000 a0) -1 -2 0 50 150 100 magnetic field B (Gauss) calculations by P.Julienne et al., NIST

  7. Tuning of interactions: three-body loss K3 = three-bodyloss rate coefficient Kraemer et al.,Nature 440, 315 (2006) ½3 / K31/4 recombinationlength½3(1000 a0) Efimovresonance scatteringlengthaS(1000 a0) K3 /a4

  8. Bloch bands Higher Bloch bands omitted Tunneling J Interaction U External potential ε Interaction potential Simple non-regularized pseudopotential Tunneling matrix element Interactions U’ No nearest neighbor interaction On-site interaction energy Tunneling J’ External energy shift No next nearest neighbor tunneling Basic concepts of lattice physics Approximations The standard Bose-Hubbard model

  9. Phase diagram Superfluid J»U µ/U • Delocalized particles • Coherent phase • No excitation gap insulator n=2 superfluid insulator n=1 J/U Experiment Mott insulator J«U External confinement ‘wedding cake structure’ • Localized particles • No phase coherence • Excitation gap Properties of the Bose-Hubbard (BH) model Groundstates at T=0 Exp‘s: Bloch, Esslinger, Greiner,…

  10. Experimental setup Measurement method Probe coherence by ToFmeasurements superfluid µ/U insulator n=1 J/U Lattice depth Tunneling J Lattice depth time Interaction U Scattering length External potential ε Dipole trap superfluid Mott insulator Probing the phase transition

  11. Observable Results ‘Kink’ in FWHM 212 a0 320 a0 427 a0 Phase transition point FWHM µ/U J/U Probing the phase transition aS= Mark et al.Phys. Rev. Lett. 107, 175301 (2011)

  12. Measurement method Amplitude modulation Experimental sequence Lattice depth time U 2U U Measuring the excitation spectrum MI excitation spectrum Elementary MI excitations

  13. Resonance splitting near U-peak U 2U 320 a0 U 2U U 427 a0 Density dependence Measuring the excitation spectrum Results aS=212 a0 Mark et al.Phys. Rev. Lett. 107, 175301 (2011)

  14. Three particles 3x two-particle interactions Effective interactions Two particles Johnson et al. New J. Phys. 11, 093022 (2009) Efimov physics Energy Energy +1/a -1/a dimer +a -a Busch et al.Found. ofPhysics 28, 549 (1998) Schneider et al. Phys. Rev. A 80, 013404 (2009) Büchler et al. Phys. Rev. Lett. 104, 090402 (2010) Efimov trimer Beyond the standard BH model Approximations Bloch bands Interaction potential Invalid for strong interactions Kraemer et al. Nature 440, 315 (2006)

  15. Measurement High density Intermediate Low density Density dependence U(2) 3U(3)-2U(2) U(2) 3xU(3) 427 a0 Three-body loss Double occupancy 3U(3)-U(2) 3U(3)-2U(2) U(2) 427 a0 427 a0 Mark et al.Phys. Rev. Lett. 107, 175301 (2011) Beyond the standard BH model Expectation U 3xU

  16. UBH 3U(3)-U(2) 2UBH U(2) 3U(3)-2U(2) Theory and Experiment Mark et al.Phys. Rev. Lett. 107, 175301 (2011) UBH 3U(3)-U(2) 2UBH U(2) 3U(3)-2U(2) (see also workby I. Bloch‘sgroup, S. Will et al., Nature 465, 197 (2010))

  17. J«|U| Mott insulator Γ3 Mott insulator J«|U| Superfluid J»|U| Metastable Highly excited state of the system Γ3 Attractive interactions BH model with negative U Three-body loss Γ3

  18. Lattice loading Repulsive Mott insulator Switch to attractive a Wait / modulate Γ3 Switch to repulsive a Observe overall heating Preparation of the attractive MI state depth 20 ER

  19. Stability of the attractive MI state Varying interactions hold time = 50 ms blueareas: narrowFeshbachresonances zerocrossing Mark et al.,to appear in PRL (2012)

  20. Varying the hold time -2000 a0 -240 a0 +220 a0 Stability of the attractive MI state Varying interactions hold time = 50 ms Mark et al.,to appear in PRL (2012)

  21. U(2) 3U(3)-2U(2) UBH U*(2) U(2) 3U(3)-2U(2) U*(2) ? De-excitation spectrum Excitation resonances U(2) 3U(3)-2U(2) Mark et al.,to appear in PRL (2012) -306 a0 -306 a0

  22. Three-body loss resonance Fast broadening of the resonance Three-body loss rate Three-body loss Γ3 Γ3 Rate of three-body loss without lattice Kraemer et al.,Nature 440, 315 (2006) Mark et al.,to appear in PRL (2012)

  23. Suppressed three-body loss: Quantum Zeno effect Analogy Large three-body loss stabilizes! :

  24. Comparison of loss widths Attractive interactions Repulsive interactions

  25. Comparison of loss widths Attractive interactions Repulsive interactions

  26. Comparison of loss widths Attractive interactions Repulsive interactions Γ3

  27. Comparison of loss widths Attractive interactions Repulsive interactions superfluid ofdimers? (Theroy: A. Daley et al., PRL 2009)

  28. Ongoing work Start withone-atom Mott insulator…

  29. Ongoing work Thenapplylatticetiltandcreate „doublons“… see Greiner group „quantummagnetism“

  30. Ongoing work: Doublon creation (very preliminary) in an arrayof 1D-tubes so far: 75% doubloncreation

  31. Ongoing work … andthenwatchdynamicsasthelatticedepthislowered…

  32. Thankyou!

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