EGAS41 - Swansea University

41 st EGAS CP 132 Gdańsk 2009
Phase dynamics of atoms in micro-traps
B. O’Sullivan, S. McEndoo, T. Busch ∗
Physics Department, University College Cork, Cork, Ireland
∗ Corresponding author: thbusch@phys.ucc.ie,
Controlling the phase of a single quantum system with high fidelity while not compromising
fast time scales is one of the goals in developing quantum information devices. This
usually requires excellent time-dependent control over several experimental parameters,
making it technically challenging. For not-completely time-critical applications, however,
adiabatic techniques can be used that allow to transfer time-dependent control into fixed
system parameters.
Here we investigate techniques for state preparation of single, ultracold atoms in systems
of spatially separated micro-traps. For such systems coherent transport can be
achieved by tunneling and it was recently shown that an analogue to the celebrated threelevel
STIRAP technique in optics can be constructed [1]. However, spatial atom-optical
systems posess various additional degrees of freedom as compared to optical systems
(e.g. multiple spatial dimensions, particle interactions, quantum statistics, etc.). They
therefore hold a large promise for developing new and exciting techniques based on dark
states.
In this work we consider the influence of dynamical as well as geometrical phases
on atoms in dark states for different experimental geometries. We first investigate the
stability of angular momentum carrying states in the standard STIRAP process and show
that it can be used for controlled phase engineering. In a second example we consider
a four trap diamond arrangement in two dimensions and show that an atom trapped
initially in a single trap can be transferred into an arbitrary, but well defined, spatial
superposition state. This is due to the accumulation of a Berry phase and the process
requires only control over individual trapping frequencies and the ability to carry out a
STIRAP type positioning sequence of the traps. We show that this process does not
only allow for large fidelities when carried out perfectly, but is also robust against many
experimental uncertainties.
References
[1] K. Eckert, M. Lewenstein, R. Corbalan, G. Birkl, W. Ertmer, W. Mompart, Phys.
Rev. A 70, 023606 (2004)
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