SESSION 13: Atoms

Chair: (Poul Jessen (University of Arizona))
3:15pm-3:45pmJacob Lampen, University of Michigan
State insensitive trapping for ground and Rydberg atoms
Abstract. We create state insensitive trapping potentials for ground and Rydberg atoms by using optical lattices having wavelengths between \(1012nm\) and \(1026nm\) that correspond to magic wavelengths for states having principal quantum numbers between \(n=30\) and \(n=65\). The spatial confinement provided by the lattice results in a suppression of motional (Doppler) dephasing. The retrieved signal of the collective atomic coherence displays oscillations at the axial trap frequency, with trap lifetimes in excess of 20 microseconds. These are an order of magnitude longer than those observed for ballistically expanding atomic clouds. The observed values of magic detunings are found to be in good agreement with the values predicted theoretically and scale approximately as \((n-3.13)^{-3}\). The enhanced ground Rydberg coherence times open new opportunities for precise creation and manipulation of entangled many-atom states and for interfacing these states with quantum optical fields.
3:45pm-4:15pmMatthew Norcia, University of Colorado JILA
Exchange interactions in a strontium superradiant laser
Abstract. I will present a characterization of collective atomic interactions mediated by the exchange of cavity photons via the 1 mHz linewidth optical clock transition in an ensemble of superradiantly emitting strontium atoms. These interactions are of a form known to generate useful entanglement through one-axis twisting dynamics and to cause a suppression of decoherence through the generation of a many-body energy gap. In addition, they are key to understanding the sensitivity of superradiant frequency references to cavity detuning. We observe signatures of these effects through precision frequency measurements of the emitted superradiant light.
4:15pm-4:45pmMichael Martin, Sandia National Laboratories
A CPHASE gate between Rydberg‐dressed neutral atoms
Abstract. Neutral atom‐based qubits are highly scalable and controllable. With optical excitation of high‐lying, strongly interacting Rydberg states, one can achieve on‐demand, laser‐controlled interactions for quantum logic operations. We present studies of entangling operations within a two‐atom system employing individually trapped ultra‐cold cesium atoms that interact via single‐photon laser coupling to a Rydberg level [1], where the Rydberg‐dressed many‐body Hamiltonian permits pairwise and beyond-pairwise interaction regimes. We describe a detailed study of a two‐atom controlled‐phase (CPHASE) gate that is insensitive to the detrimental effects of atomic motion and light shifts, and that should enable high-quality entangling operations between atom pairs or within larger ensembles. We also present work towards larger‐scale systems employing reconfigurable traps formed via digital holography, with the goal of scaling the successes of the two‐atom system. [1] Y.‐Y. Jau et al., “Entangling atomic spins with a Rydberg‐dressed spin‐flip blockade,” Nat. Phys. 12, 71‐74 (2016). This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories.
4:45pm-5:15pmBharath H. M., Georgia Institute of Technology
Singular loops and their non-Abelian geometric phases in ultracold spin-1 atoms
Abstract. We use coherent control of ultracold Rubidium atoms in a dipole trap to experimentally explore the recently introduced non-Abelian geometric phases of singular loops inside the Bloch ball [1]. Non-Abelian and non-adiabatic variants of Berry's geometric phase have been pivotal in the recent advances in fault-tolerant quantum computation gates, while Berry's phase itself is at the heart of the study of topological phases of matter. In [1], geometric phase was generalized to loops on or inside the Bloch ball and was formulated as an SO(3) operator, carried by the spin-fluctuation tensor of a spin-1 system . The special class of loops inside the Bloch ball passing through the center, which we refer to as singular loops, are significant in two ways. First, their geometric phase is non-Abelian and second, their geometrical properties are qualitatively different from the nearby non-singular loops, making them akin to critical points of a quantum phase transition. [1] H. M. Bharath, “Non-Abelian geometric phases carried by the spin fluctuation tensor”, arXiv:1702.08564

SQuInT Chief Organizer
Akimasa Miyake, Assistant Professor

SQuInT Co-Organizer
Mark M. Wilde, Assistant Professor LSU

SQuInT Administrator
Gloria Cordova
505 277-1850

SQuInT Founder
Ivan Deutsch, Regents' Professor

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