Observations ofλ/4structure in a low-loss radio-frequency-dressed optical lattice

Abstract

We load a Bose-Einstein condensate into a one-dimensional (1D) optical lattice altered through the use of radiofrequency (rf) dressing. The rf resonantly couples the three levels of the 87 Rb F = 1 manifold and combines with a spin-dependent "bare" optical lattice to result in adiabatic potentials of variable shape, depth, and spatial frequency content. We choose dressing parameters such that the altered lattice is stable over lifetimes exceeding tens of ms at higher depths than in previous work. We observe significant differences between the BEC momentum distributions of the dressed lattice as compared to the bare lattice, and find general agreement with a 1D band structure calculation informed by the dressing parameters. Previous work using such lattices was limited by very shallow dressed lattices and strong Landau-Zener tunnelling loss between adiabatic potentials, equivalent to failure of the adiabatic criterion. In this work we operate with significantly stronger rf coupling (increasing the avoided-crossing gap between adiabatic potentials), observing dressed lifetimes of interest for optical lattice-based analogue solid-state physics.The optical lattice is a versatile tool for trapping and control of neutral atoms and for studying both singleparticle and many-body quantum physics. It has proven useful to optical atomic clock development [1], to the development of quantum-computing proposals [2][3][4], and to solid-state analogues and quantum simulations [5,6], including the ability to resolve these systems at the singleatom level [7][8][9]. While early work focused on simple lattices of λ/2 periodicity (where λ is the wavelength of the lattice laser), including square (2D) and cubic (3D) lattices, more complex periodic potentials were sought out in order to enhance existing lattice-physics experiments and to explore less well-understood many-body physics. Recently, new lattice geometries (including the triangular, honeycomb, kagome, double-well, and checkerboard lattice) have been explored using various techniques, including the use of dual commensurate lattice lasers [10] as well as through holography [11]. Additionally, lattice substructure in 1D has been generated using Raman transitions [12][13][14][15].Taking a wholly different approach, other work [16-18] introduced a method of altering lattice geometry and topology based on the notion of radiofrequency (rf) dressing of spin-dependent lattice potentials [19]. The theoretical work [17,18] aimed at the exploitation of the resulting adiabatic potentials' faster tunnelling timescales and higher interaction energies, as well as the associated higher temperature scale. The experimental work [16] showed that it was possible to generate 2D dressed lattices that in principle had tailored subwavelength structure, in particular pointing the way to toroidal singlesite wavefunctions [20]. This work was limited, however, to dressed lattices of rather small depth, preventing the realization of tight-binding lattice wavefunctions with lifetimes appropriate to the s...

Efficient production of an 87Rb F = 2, mF = 2 Bose-Einstein condensate in a hybrid trap

“…In our configuration of QMT and ODT, for B = B lev , the trapping force in the axial direction is 2μB lev , compared to μB lev /2 in the more common hybrid trap configuration [3,[7][8][9][10][11][12][13][14], in which the strong axis of the QMT is vertical, while the ODT is in the horizontal plane. This provides a factor of four enhancement in the peak density in our case 1 .…”

“…The hybrid trap has been successfully applied in several experiments, for 87 Rb [3,[7][8][9][10][11][12][13], 85 Rb [14], 133 Cs [8] and 23 Na [10]. In all these previous hybrid traps the symmetry axis of the QMT is placed vertically, while the ODT is in the horizontal plane, and forced evaporative cooling in the QMT is done by RF radiation.…”

Geometrical Pumping with a Bose-Einstein Condensate

“…This spatially varying effective magnetic field produces a 1D bipartite lattice [2, 32] with lattice constant a = λ R /2 with adiabatic (Born-Oppenheimer) potentials depicted in Fig. 1(c).…”

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

“…As the lattice spacing determines many of the energy scales in cold-atom lattice systems, it has been of interest to produce optical lattices with smaller spacings in order to increase relevant energy scales [10,11]. Approaches to making subwavelength-spaced optical lattices have been proposed [12] and realized [13,14] based on multiphoton effects, and on adiabatic dressing of different spin dependent lattices [15,16].…”