Dark State Optical Lattice with a Subwavelength Spatial Structure

Abstract

We report on the experimental realization of a conservative optical lattice for cold atoms with a subwavelength spatial structure. The potential is based on the nonlinear optical response of three-level atoms in laser-dressed dark states, which is not constrained by the diffraction limit of the light generating the potential. The lattice consists of a one-dimensional array of ultranarrow barriers with widths less than 10 nm, well below the wavelength of the lattice light, physically realizing a Kronig-Penney potential. We study the band structure and dissipation of this lattice and find good agreement with theoretical predictions. Even on resonance, the observed lifetimes of atoms trapped in the lattice are as long as 44 ms, nearly 10^{5} times the excited state lifetime, and could be further improved with more laser intensity. The potential is readily generalizable to higher dimensions and different geometries, allowing, for example, nearly perfect box traps, narrow tunnel junctions for atomtronics applications, and dynamically generated lattices with subwavelength spacings.

Management of the correlations of UltracoldBosons in triple wells

“…The tilt αx renders the trapping potential similar to that of charged particles in a constant electric field and can be realized by applying a magnetic field gradient to ultracold neutral bosons in a lattice. We note the possibility of achieving, virtually, any periodic lattice in the experiment [44]. The potential is plotted in figure 1(a) for αä[0,16].…”

Floquet engineering of optical lattices with spatial features and periodicity below the diffraction limit

“…Recently, optical lattices based on the nonlinear optical response of dark states [17,18] were realized [19] with λ/2 periodicity but strongly subwavelength structure within a unit cell, consisting of a Kronig-Penney-like (KP) lattice of narrow repulsive barriers of width ;λ/50. Time averaging a stroboscopically applied lattice potential with high spatial frequency Fourier components can give rise to an average potential with periodicity and spatial features smaller than λ/2 [10].…”

“…This requirement suggests that ω T be as large as possible. As we discuss below, the particular realization of W 0 (x, t) using a darkstate lattice [19] has an additional requirement of spin adiabaticity that limits the maximum allowable ω T . The dark-state lattice is an artificial scalar gauge potential [17-19, 22, 23] experienced by an atom in the dark-state eigenfunction of a three-level Λ-system with a spatially dependent spin composition.…”

“…This spin manipulation can be seen as a stimulated Raman adiabatic passage (STIRAP) process [24] and adiabaticity requirements set an upper bound on the window for usable ω T within which the atoms are simultaneously motionally diabatic and spin adiabatic. Understanding the practical limits of these constraints requires a detailed consideration of the system dynamics, which we apply to the specific 171 Yb system previously used to demonstrate the dark-state lattice [19].…”

Topological states in the Kronig–Penney model with arbitrary scattering potentials

“…Despite its underlying simplicity that neglects interactions between the particles, it is particularly well suited to describe the behavior of electrons in metals [2][3][4][5][6][7]. More recently an experimental realization of the KP potential for ultracold atoms in optical lattices was proposed [8] and demonstrated [9] .…”