Fast manipulation of Bose–Einstein condensates with an atom chip

Abstract

We present a detailed theoretical analysis of the implementation of shortcut-to-adiabaticity protocols for the fast transport of neutral atoms with atom chips. The objective is to engineer transport ramps with durations not exceeding a few hundred milliseconds to provide metrologically relevant input states for an atomic sensor. Aided by numerical simulations of the classical and quantum dynamics, we study the behavior of a Bose-Einstein condensate in an atom chip setup with realistic anharmonic trapping. We detail the implementation of fast and controlled transports over large distances of several millimeters, i.e. distances 1000 times larger than the size of the atomic cloud. A subsequent optimized release and collimation step demonstrates the capability of our transport method to generate ensembles of quantum gases with expansion speeds in the picokelvin regime. The performance of this procedure is analyzed in terms of collective excitations reflected in residual center of mass and size oscillations of the condensate. We further evaluate the robustness of the protocol against experimental imperfections.

Shortcuts to adiabaticity: Concepts, methods, and applications

“…Another phenomenological way out for some applications may be to optimize control parameters experimentally. For example Cohn et al (2018) propose an optimization of a bang-bang protocol for the external parameter to produce entangled states in a Dicke model realized in a two-dimensional array of trapped ions in a Penning trap.…”

“…Penning traps. Shortcuts have been applied as well to Penning traps:Kiely et al (2015) designed via invariants a non-adiabatic change of the magnetic field strength to change the radial spread without final excitations, andCohn et al (2018) implemented experimentally a protocol to produce entangled states in a Dicke model realized in a two dimensional array of trapped ions.Rotations. Palmero et al (2016) provided invariantbased shortcuts to perform fast rotations of an ion in a 1D trap.…”

Realistic shortcuts to adiabaticity in optical transfer

“…Devising an STA trajectory amounts to finding a non-adiabatic path that satisfies (6a):(6b). Several such trajectories were suggested in the literature [16,18,19,33,[38][39][40][41][42] and implemented experimentally [14,15,20].…”

“…Invariantbased methods, on which we focus in this work, take the system back to the adiabatic path only at the end of the process by engineering the trajectory to satisfy the boundary conditions at initial and final times and, in general, the Ermakov equation in between [2,3]. Among the many fields who can benefit from STA are quantum computation [4][5][6][7], quantum control [8][9][10][11], quantum thermodynamics [12,13] and transport [14][15][16][17][18][19][20] or manipulation [21][22][23][24][25] of ions and ultracold neutral atoms.…”

Focus on Shortcuts to Adiabaticity

“…One clear instance is in atom chip technology, where several applications have been limited by the long times required to change the location of the Bose-Einstein condensate cloud. Corgier et al [63] report the fast and controlled transport of neutral atoms in an atom chip over large distances, of order 1000 times the atomic cloud size. The authors further report expansion speeds in the picokelvin regime by tailoring the release and collimation of the atomic cloud.…”