Stanford Advisors

All Publications

  • Photon-Mediated Peierls Transition of a 1D Gas in a Multimode Optical Cavity PHYSICAL REVIEW LETTERS Rylands, C., Guo, Y., Lev, B. L., Keeling, J., Galitski, V. 2020; 125 (1)
  • Dynamical Spin-Orbit Coupling of a Quantum Gas PHYSICAL REVIEW LETTERS Kroeze, R. M., Guo, Y., Lev, B. L. 2019; 123 (16)
  • Sign-Changing Photon-Mediated Atom Interactions in Multimode Cavity Quantum Electrodynamics PHYSICAL REVIEW LETTERS Guo, Y., Kroeze, R. M., Vaidya, V. D., Keeling, J., Lev, B. L. 2019; 122 (19): 193601


    Sign-changing interactions constitute a crucial ingredient in the creation of frustrated many-body systems such as spin glasses. We present here the demonstration of a photon-mediated sign-changing interaction between Bose-Einstein-condensed atoms in a confocal cavity. The interaction between two atoms is of an unusual, nonlocal form proportional to the cosine of the inner product of the atoms' position vectors. This interaction arises from the differing Gouy phase shifts of the cavity's degenerate modes. The interaction drives a nonequilibrium Dicke-type phase transition in the system leading to atomic checkerboard density-wave order. Because of the Gouy phase anomalies, the checkerboard pattern can assume either a sinelike or cosinelike character. This state is detected via the holographic imaging of the cavity's superradiant emission. Together with a companion paper [Y. Guo, V. D. Vaidya, R. M. Kroeze, R. A. Lunney, B. L. Lev, and J. Keeling, Emergent and broken symmetries of atomic self-organization arising from Gouy phases in multimode cavity QED, Phys. Rev. A 99, 053818 (2019)PLRAAN2469-992610.1103/PhysRevA.99.053818], we explore this interaction's influence on superradiant phase transitions in multimode cavities. Employing this interaction in cavity QED spin systems may enable the creation of artificial spin glasses and quantum neural networks.

    View details for DOI 10.1103/PhysRevLett.122.193601

    View details for Web of Science ID 000468228200005

    View details for PubMedID 31144918

  • Emergent and broken symmetries of atomic self-organization arising from Gouy phase shifts in multimode cavity QED PHYSICAL REVIEW A Guo, Y., Vaidya, V. D., Kroeze, R. M., Lunney, R. A., Lev, B. L., Keeling, J. 2019; 99 (5)
  • Spinor Self-Ordering of a Quantum Gas in a Cavity PHYSICAL REVIEW LETTERS Kroeze, R. M., Guo, Y., Vaidya, V. D., Keeling, J., Lev, B. L. 2018; 121 (16)
  • Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED PHYSICAL REVIEW X Vaidya, V. D., Guo, Y., Kroeze, R. M., Ballantine, K. E., Kollar, A. J., Keeling, J., Lev, B. L. 2018; 8 (1)
  • Spinor Self-Ordering of a Quantum Gas in a Cavity. Physical review letters Kroeze, R. M., Guo, Y. n., Vaidya, V. D., Keeling, J. n., Lev, B. L. 2018; 121 (16): 163601


    We observe the joint spin-spatial (spinor) self-organization of a two-component Bose-Einstein condensate (BEC) strongly coupled to an optical cavity. This unusual nonequilibrium Hepp-Lieb-Dicke phase transition is driven by an off-resonant Raman transition formed from a classical pump field and the emergent quantum dynamical cavity field. This mediates a spinor-spinor interaction that, above a critical strength, simultaneously organizes opposite spinor states of the BEC on opposite checkerboard configurations of an emergent 2D lattice. The resulting spinor density-wave polariton condensate is observed by directly detecting the atomic spin and momentum state and by holographically reconstructing the phase of the emitted cavity field. The latter provides a direct measure of the spin state, and a spin-spatial domain wall is observed. The photon-mediated spin interactions demonstrated here may be engineered to create dynamical gauge fields and quantum spin glasses.

    View details for PubMedID 30387632

  • Supermode-density-wave-polariton condensation with a Bose-Einstein condensate in a multimode cavity. Nature communications Kollár, A. J., Papageorge, A. T., Vaidya, V. D., Guo, Y., Keeling, J., Lev, B. L. 2017; 8: 14386-?


    Phase transitions, where observable properties of a many-body system change discontinuously, can occur in both open and closed systems. By placing cold atoms in optical cavities and inducing strong coupling between light and excitations of the atoms, one can experimentally study phase transitions of open quantum systems. Here we observe and study a non-equilibrium phase transition, the condensation of supermode-density-wave polaritons. These polaritons are formed from a superposition of cavity photon eigenmodes (a supermode), coupled to atomic density waves of a quantum gas. As the cavity supports multiple photon spatial modes and because the light-matter coupling can be comparable to the energy splitting of these modes, the composition of the supermode polariton is changed by the light-matter coupling on condensation. By demonstrating the ability to observe and understand density-wave-polariton condensation in the few-mode-degenerate cavity regime, our results show the potential to study similar questions in fully multimode cavities.

    View details for DOI 10.1038/ncomms14386

    View details for PubMedID 28211455

    View details for PubMedCentralID PMC5321730