1 loring New States of Matter in the p-orbi Bands of Optical Lattices Congjun Wu Kavli Institute for Theoretical Physics, UCSB . Wu, D. Bergman, L. Balents, and S. Das Sarma, cond-mat/0701788. . Wu, W. V. Liu, J. Moore and S. Das Sarma, PRL 97, 190406 (2006). . V. Liu and C. Wu, PRA 74, 13607 (2006). University of Maryland, 02/05/2007
46
Embed
Exploring New States of Matter in the p -orbital Bands of Optical Lattices
Exploring New States of Matter in the p -orbital Bands of Optical Lattices. Congjun Wu. Kavli Institute for Theoretical Physics, UCSB. C. Wu, D. Bergman, L. Balents, and S. Das Sarma, cond-mat/0701788. C. Wu, W. V. Liu, J. Moore and S. Das Sarma, PRL 97, 190406 (2006). - PowerPoint PPT Presentation
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Exploring New States of Matter in the p-orbitalBands of Optical Lattices
Congjun Wu
Kavli Institute for Theoretical Physics, UCSB
C. Wu, D. Bergman, L. Balents, and S. Das Sarma, cond-mat/0701788.C. Wu, W. V. Liu, J. Moore and S. Das Sarma, PRL 97, 190406 (2006).W. V. Liu and C. Wu, PRA 74, 13607 (2006).
University of Maryland, 02/05/2007
2
Collaborators
L. Balents UCSB
Many thanks to I. Bloch, L. M. Duan, T. L. Ho, T. Mueller, Z. Nussinov for very helpful discussions.
D. Bergman UCSB
W. V. Liu Univ. of Pittsburg
S. Das Sarma Univ. of Maryland
J. Moore Berkeley
3
Outline
• Introduction.
• New features of orbital physics in optical lattices.
- Rapid progress of cold atom physics in optical lattices.
Bosons: novel superfluidity with time-reversal symmetry breaking (square, triangular lattices).
- New direction: orbital physics in high-orbital bands; pioneering experiments.
Fermions: flat bands and crystallization in honeycomb lattice.
4
M. H. Anderson et al., Science 269, 198 (1995)
Bose-Einstein condensation
314 cm10~1~ nKTBEC
• Bosons in magnetic traps: dilute and weakly interacting systems.
5
New era: optical lattices• New opportunity to study strongly correlated systems.
• Interaction effects are tunable by varying laser intensity.
U
tt : inter-site tunnelingU: on-site interaction
6
Superfluid-Mott insulator transitionSuperfluid
Greiner et al., Nature (2001).
Rb87
Mott insulator
t<<Ut>>U
7
)()()()()( 212121 GkkknknknknG
• 1st order coherence disappears in the Mott-insulating state.
)(kn
• Noise correlation function oscillates at reciprocal lattice vectors; bunching effect of bosons.
Noise correlation (time of flight) in Mott-insulators
Folling et al., Nature 434, 481 (2005); Altman et al., PRA 70, 13603 (2004).
1k
2k
8
Two dimensional superfluid-Mott insulator transition
I. B. Spielman et al., cond-mat/0606216.
12/ REV 20/ REV 21/ REV
9
Fermionic atoms in optical lattices
U
t
ii
iji i
iji
n
nnUcctH
,,
• Observation of Fermi surface.
Low density: metal high density: band insulator
2
7
2
9
2
9
2
940 ,: FmK
Esslinger et al., PRL 94:80403 (2005)
• Quantum simulations to the Hubbard model.e.g. can 2D Hubbard model describe high Tc cuprates?
10
Good timing: pioneering experiments; double-well lattice (NIST) and square lattice (Mainz).
New direction: orbital physics in optical lattices
• Orbital physics: studying new physics of fermions and bosons in high-orbital bands.
J. J. Sebby-Strabley, et al., PRA 73, 33605 (2006); T. Mueller and I. Bloch et al.