@article {liang_coherence_2021,
title = {Coherence and decoherence in the {Harper}-{Hofstadter} model},
journal = {Phys. Rev. Res.},
volume = {3},
number = {2},
year = {2021},
note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article},
month = {apr},
abstract = {We quantum simulated the 2D Harper-Hofstadter (HH) lattice model in a highly elongated tube geometry-three sites in circumference-using an atomic Bose-Einstein condensate. In addition to the usual transverse (out-of-plane) magnetic flux, piercing the surface of the tube, we threaded a longitudinal flux Phi(L) down the axis of the tube. This geometry evokes an Aharonov-Bohm interferometer, where noise in Phi(L) would readily decohere the interference present in trajectories encircling the tube. We observe this behavior only when transverse flux is a rational fraction of the flux quantum and remarkably find that for irrational fractions the decoherence is absent. Furthermore, at rational values of transverse flux, we show that the time evolution averaged over the noisy longitudinal flux matches the time evolution at nearby irrational fluxes. Thus, the appealing intuitive picture of an Aharonov-Bohm interferometer is insufficient. Instead, we quantitatively explain our observations by transforming the HH model into a collection of momentum-space Aubry-Andre models.},
doi = {10.1103/PhysRevResearch.3.023058},
author = {Liang, Q-Y and Trypogeorgos, D. and Valdes-Curiel, A. and Tao, J. and Zhao, M. and Spielman, I. B.}
}
@article {valdes-curiel_topological_2021,
title = {Topological features without a lattice in {Rashba} spin-orbit coupled atoms},
journal = {Nat. Commun.},
volume = {12},
number = {1},
year = {2021},
note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article},
month = {jan},
abstract = {Topological order can be found in a wide range of physical systems, from crystalline solids, photonic meta-materials and even atmospheric waves to optomechanic, acoustic and atomic systems. Topological systems are a robust foundation for creating quantized channels for transporting electrical current, light, and atmospheric disturbances. These topological effects are quantified in terms of integer-valued {\textquoteleft}invariants{\textquoteright}, such as the Chern number, applicable to the quantum Hall effect, or the Z2 invariant suitable for topological insulators. Here, we report the engineering of Rashba spin-orbit coupling for a cold atomic gas giving non-trivial topology, without the underlying crystalline structure that conventionally yields integer Chern numbers. We validated our procedure by spectroscopically measuring both branches of the Rashba dispersion relation which touch at a single Dirac point. We then measured the quantum geometry underlying the dispersion relation using matter-wave interferometry to implement a form of quantum state tomography, giving a Berry{\textquoteright}s phase with magnitude . This implies that opening a gap at the Dirac point would give two dispersions (bands) each with half-integer Chern number, potentially implying new forms of topological transport.Here, the authors study topology in spin-orbit coupled 87Rb atoms by using time domain spectroscopy and quantum state tomography. They measure full quantum state to extract the Berry phase of the system and show signatures of a half-integer Chern index.},
issn = {2041-1723},
doi = {10.1038/s41467-020-20762-4},
author = {Valdes-Curiel, A. and Trypogeorgos, D. and Liang, Q. -Y. and Anderson, R. P. and Spielman, I. B.}
}
@article {anderson_realization_2020,
title = {Realization of a deeply subwavelength adiabatic optical lattice},
journal = {Phys. Rev. Res.},
volume = {2},
number = {1},
year = {2020},
note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article},
month = {feb},
abstract = {We propose and describe our realization of a deeply subwavelength optical lattice for ultracold neutral atoms using N resonantly Raman-coupled internal degrees of freedom. Although counterpropagating lasers with wavelength. provided two-photon Raman coupling, the resultant lattice period was lambda/2N, an N-fold reduction as compared to the conventional lambda/2 lattice period. We experimentally demonstrated this lattice built from the three F = 1 Zeeman states of a Rb-87 Bose-Einstein condensate, and generated a lattice with a lambda/6 = 132 nm period from lambda = 790 nm lasers. Lastly, we show that adding an additional rf-coupling field converts this lattice into a superlattice with N wells uniformly spaced within the original lambda/2 unit cell.},
doi = {10.1103/PhysRevResearch.2.013149},
author = {Anderson, R. P. and Trypogeorgos, D. and Valdes-Curiel, A. and Liang, Q-Y and Tao, J. and Zhao, M. and Andrijauskas, T. and Juzeliunas, G. and Spielman, I. B.}
}
@article {ISI:000423107800020,
title = {Synthetic clock transitions via continuous dynamical decoupling},
journal = {PHYSICAL REVIEW A},
volume = {97},
number = {1},
year = {2018},
month = {JAN 16},
pages = {013407},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {Decoherence of quantum systems due to uncontrolled fluctuations of the environment presents fundamental obstacles in quantum science. Clock transitions which are insensitive to such fluctuations are used to improve coherence, however, they are not present in all systems or for arbitrary system parameters. Here we create a trio of synthetic clock transitions using continuous dynamical decoupling in a spin-1 Bose-Einstein condensate in which we observe a reduction of sensitivity to magnetic-field noise of up to four orders of magnitude; this work complements the parallelwork byAnderson et al. {[}R. P. Anderson et al., following paper, Phys. Rev. A 97, 013408 (2018)]. In addition, using a concatenated scheme, we demonstrate suppression of sensitivity to fluctuations in our control fields. These field-insensitive states represent an ideal foundation for the next generation of cold-atom experiments focused on fragile many-body phases relevant to quantum magnetism, artificial gauge fields, and topological matter.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
issn = {2469-9926},
doi = {10.1103/PhysRevA.97.013407},
author = {Trypogeorgos, D. and Valdes-Curiel, A. and Lundblad, N. and Ian B Spielman}
}
@article {ISI:000387905800007,
title = {Vortex nucleation in a Bose-Einstein condensate: from the inside out},
journal = {NEW JOURNAL OF PHYSICS},
volume = {18},
year = {2016},
month = {NOV 4},
pages = {113009},
abstract = {We observed a new mechanism for vortex nucleation in Bose-Einstein condensates (BECs) subject to synthetic magnetic fields. We made use of a strong synthetic magnetic field initially localized between a pair of merging BECs to rapidly create vortices in the bulk of the merged condensate. Unlike previous implementations and in agreement with our Gross-Pitaevskii equation simulations, our dynamical process rapidly injects vortices into our system{\textquoteright}s bulk, and with initial number in excess of the system{\textquoteright}s equilibrium vortex number.},
issn = {1367-2630},
doi = {10.1088/1367-2630/18/11/113009},
author = {Price, R. M. and Trypogeorgos, D. and Campbell, D. L. and Putra, A. and Valdes-Curiel, A. and Ian B Spielman}
}