Resonant excitations of a Bose Einstein condensate in an optical lattice

Abstract

We investigate experimentally a Bose Einstein condensate placed in a 1D optical lattice whose phase or amplitude is modulated in a frequency range resonant with the first bands of the band structure. We study the combined effect of the strength of interactions and external confinement on the 1 and 2-phonon transitions. We identify lines immune or sensitive to atom-atom interactions. Experimental results are in good agreement with numerical simulations. Using the band mapping technique, we get a direct access to the populations that have undergone n-phonon transitions for each modulation frequency.

Chaos-assisted tunneling resonances in a synthetic Floquet superlattice

“…We superimpose to the horizontal optical dipole beam ( x axis) of the trap a 1D optical lattice obtained from the interference of two counter-propagating laser beams. We engineer the phase and amplitude of the lattice via three acousto-optic modulators ( 72 ): One is dedicated to the control of the lattice laser intensity, and the others, driven by phase-locked synthesizers, control the relative phase, φ, between the two lattice beams. Introducing the dimensionless variables p = 2π P /( m ω d ), x = 2π X / d , where m is the atomic mass, d = 532 nm is the lattice spacing, and X and P are the position and momentum along the standing wave and normalizing the time t to the modulation angular frequency ω, the Hamiltonian that governs the dynamics reads ( 40 , 41 ) …”

“…To experimentally implement this Hamiltonian, we first load the BEC in a static lattice by a smooth increase of the lattice intensity ( 72 ). We then apply the protocol ( 41 ) described in Fig.…”

Quantum State Control of a Bose-Einstein Condensate in an Optical Lattice

“…Interestingly, it is possible to produce in a fast manner quantum states that cannot be reached by adiabatic transformations. This method enables us to efficiently prepare lattice eigenstates in a straightforward way, as compared to periodic modulations of phase or amplitude [63], and is also robust to the presence of a small external confinement.…”

Parametric Instabilities of Interacting Bosons in Periodically Driven 1D Optical Lattices

“…In time-periodic systems, energy conservation is relaxed due to the possibility to absorb and emit energy quanta from the drive, and any driven ergodic system is expected to eventually heat up to infinite temperature [23,24]. Recent experiments [25][26][27][28][29] have addressed this problem for interacting atoms in shaken optical lattices. In particular, it has been shown [27,[30][31][32][33] that heating rates are well captured by a Floquet Fermi's golden rule (FFGR) approach, if they are evaluated at sufficiently long times.…”