%0 Journal Article %D 2019 %T Floquet engineering of optical lattices with spatial features and periodicity below the diffraction limit %A S. Subhankar %A P. Bienias %A P. Titum %A T-C. Tsui %A Y. Wang %A Alexey V. Gorshkov %A S. L. Rolston %A J. V. Porto %X

Floquet engineering or coherent time periodic driving of quantum systems has been successfully used to synthesize Hamiltonians with novel properties. In ultracold atomic systems, this has led to experimental realizations of artificial gauge fields, topological band structures, and observation of dynamical localization, to name just a few. Here we present a Floquet-based framework to stroboscopically engineer Hamiltonians with spatial features and periodicity below the diffraction limit of light used to create them by time-averaging over various configurations of a 1D optical Kronig-Penney (KP) lattice. The KP potential is a lattice of narrow subwavelength barriers spaced by half the optical wavelength (λ/2) and arises from the non-linear optical response of the atomic dark state. Stroboscopic control over the strength and position of this lattice requires time-dependent adiabatic manipulation of the dark state spin composition. We investigate adiabaticity requirements and shape our time-dependent light fields to respect the requirements. We apply this framework to show that a λ/4-spaced lattice can be synthesized using realistic experimental parameters as an example, discuss mechanisms that limit lifetimes in these lattices, explore candidate systems and their limitations, and treat adiabatic loading into the ground band of these lattices.

%8 06/18/2019 %G eng %U https://arxiv.org/abs/1906.07646 %0 Journal Article %D 2018 %T Coherent optical nano-tweezers for ultra-cold atoms %A P. Bienias %A S. Subhankar %A Y. Wang %A T-C Tsui %A F. Jendrzejewski %A T. Tiecke %A G. Juzeliūnas %A L. Jiang %A S. L. Rolston %A J. V. Porto %A Alexey V. Gorshkov %X

There has been a recent surge of interest and progress in creating subwavelength free-space optical potentials for ultra-cold atoms. A key open question is whether geometric potentials, which are repulsive and ubiquitous in the creation of subwavelength free-space potentials, forbid the creation of narrow traps with long lifetimes. Here, we show that it is possible to create such traps. We propose two schemes for realizing subwavelength traps and demonstrate their superiority over existing proposals. We analyze the lifetime of atoms in such traps and show that long-lived bound states are possible. This work opens a new frontier for the subwavelength control and manipulation of ultracold matter, with applications in quantum chemistry and quantum simulation.

%G eng %U https://arxiv.org/abs/1808.02487 %0 Journal Article %J Physical Review Letters %D 2016 %T Anomalous broadening in driven dissipative Rydberg systems %A E. A. Goldschmidt %A T. Boulier %A R. C. Brown %A S. B. Koller %A J. T. Young %A Alexey V. Gorshkov %A S. L. Rolston %A J. V. Porto %X We observe interaction-induced broadening of the two-photon 5s-18s transition in 87Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly two orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with spontaneously created populations of nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms. %B Physical Review Letters %V 116 %P 113001 %8 2016/03/16 %G eng %U http://arxiv.org/abs/1510.08710 %N 11 %R 10.1103/PhysRevLett.116.113001