TY - JOUR T1 - Floquet engineering of optical lattices with spatial features and periodicity below the diffraction limit Y1 - 2019 A1 - S. Subhankar A1 - P. Bienias A1 - P. Titum A1 - T-C. Tsui A1 - Y. Wang A1 - Alexey V. Gorshkov A1 - S. L. Rolston A1 - J. V. Porto AB -

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.

UR - https://arxiv.org/abs/1906.07646 ER - TY - JOUR T1 - Coherent optical nano-tweezers for ultra-cold atoms Y1 - 2018 A1 - P. Bienias A1 - S. Subhankar A1 - Y. Wang A1 - T-C Tsui A1 - F. Jendrzejewski A1 - T. Tiecke A1 - G. Juzeliūnas A1 - L. Jiang A1 - S. L. Rolston A1 - J. V. Porto A1 - Alexey V. Gorshkov AB -

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.

UR - https://arxiv.org/abs/1808.02487 ER -