Quantum phases of ultracold atomic gases

Ultracold atomic gases exhibit a fascinating insulator-superfluid quantum phase transition in the presence of an applied optical lattice potential, as reviewed in this article by Barbara Levi, Physics Today, 55, April 2002, page 18. Paper 1 predicts new phases and quantum critical points which can be induced simply by applying a strong potential gradient to a Mott insulator created in this manner. Paper 2 investigates a variety of non-equilibrium processes that can be studied in the vicinity of the superfluid-insulator transition.


  1. Mott insulators in strong electric fields, S. Sachdev, K. Sengupta, and S.M. Girvin, Physical Review B 66, 075128 (2002); cond-mat/0205169.
  2. Non-equilibrium Gross-Pitaevskii dynamics of boson lattice models, A. Polkovnikov, S. Sachdev, and S.M. Girvin, Physical Review A 66, 053607 (2002); cond-mat/0206490.
  3. Scratching the Bose surface, S. Sachdev, Nature 418, 739 (2002); cond-mat/0208326.
  4. Competing density-wave orders in a one-dimensional hard-boson model, P. Fendley, K. Sengupta, and S. Sachdev, Physical Review B 69, 075106 (2004); cond-mat/0309438.
  5. Quench dynamics across quantum critical points, K. Sengupta, S. Powell, and S. Sachdev, Physical Review A 69, 053616 (2004); cond-mat/0311355.
  6. Quantum phase transition in an atomic Bose gas with a Feshbach resonance, M. W. J. Romans, R. A. Duine, S. Sachdev, and H. T. C. Stoof, Physical Review Letters 93, 020405 (2004); cond-mat/0312446.
  7. Depletion of the Bose-Einstein condensate in Bose-Fermi mixtures, S. Powell, S. Sachdev, and H. P. Büchler, Physical Review B 72, 024534 (2005); cond-mat/0502299.
  8. Quantum criticality of a Fermi gas with a spherical dispersion minimum, K. Yang and S. Sachdev, Physical Review Letters 96, 187001 (2006); cond-mat/0511641.
  9. Fermi surfaces and Luttinger's theorem in paired fermion systems, S. Sachdev and K. Yang, Physical Review B 73, 174504 (2006); cond-mat/0602032.
  10. Excited state spectra at the superfluid-insulator transition out of paired condensates, S. Powell and S. Sachdev, Physical Review A 75, 031601 (2007); cond-mat/0608611.
  11. Renormalization group fixed points, universal phase diagram, and 1/N expansion for quantum liquids with interactions near the unitarity limit, P. Nikolic and S. Sachdev, Physical Review A 75, 033608 (2007); cond-mat/0609106.
  12. Spin dynamics across the superfluid-insulator transition of spinful bosons, S. Powell and S. Sachdev, Physical Review A 76, 033612 (2007); cond-mat/0703011.
  13. Superfluid-insulator transitions of the Fermi gas with near-unitary interactions in a periodic potential, E. G. Moon, P. Nikolic, and S. Sachdev, Physical Review Letters 99, 230403 (2007); arXiv:0707.2383.
  14. Radio frequency spectroscopy of a strongly imbalanced Feshbach-resonant Fermi gas, M. Veillette, E. G. Moon, A. Lamacraft, L. Radzihovsky, S. Sachdev, and D.E. Sheehy, Physical Review A 78, 033614 (2008); arXiv:0803.2517.
  15. Dilute Fermi and Bose Gases, S. Sachdev, adapted from Chapter 16 of Quantum Phase Transitions, Second Edition, by S. Sachdev, Cambridge University Press (forthcoming); contribution to Lecture Notes in Physics, "BCS-BEC crossover and the Unitary Fermi Gas" edited by W. Zwerger; arXiv:1105.1793.
  16. Correlated phases of bosons in tilted, frustrated lattices, S. Pielawa, T. Kitagawa, E. Berg, and S. Sachdev, Physical Review B 83, 205135 (2011); arXiv:1101.2897
  17. Dicke quantum spin glass of atoms and photons, P. Strack and S. Sachdev, Physical Review Letters 107, 277202 (2011); arXiv:1109.2119
  18. Frustrated quantum Ising spins simulated by spinless bosons in a tilted lattice: from a quantum liquid to antiferromagnetic order, S. Pielawa, E. Berg, and S. Sachdev, Physical Review B 86, 184435 (2012); arXiv:1203.6653
  19. Spectral functions of the Higgs mode near two-dimensional quantum critical points, D. Podolsky and S. Sachdev, D. Podolsky and S. Sachdev, Physical Review B 86, 054508 (2012); arXiv:1205.2700
  20. Quantum charge glasses of itinerant fermions with cavity-mediated long-range interactions, M. Müller, P. Strack and S. Sachdev, Physical Review A 86, 023604 (2012); arXiv:1205.4027
  21. Mobile impurity near the superfluid-Mott insulator quantum critical point in two dimensions, M. Punk and S. Sachdev, Physical Review A 87, 033618 (2013); arXiv:1212.1161
  22. Keldysh approach for non-equilibrium phase transitions in quantum optics: beyond the Dicke model in optical cavities, E. G. Dalla Torre, S. Diehl, M. D. Lukin, S. Sachdev, and P. Strack, Physical Review A 87, 023831 (2013); arXiv:1210.3623
  23. Dicke Quantum Spin and Photon Glass in Optical Cavities: Non-equilibrium theory and experimental signatures, M. Buchhold, P. Strack, S. Sachdev, and S. Diehl, Physical Review A 87, 063622 (2013); arXiv:1304.5196