479 research outputs found
Quantum Wires and Quantum Dots for Neutral Atoms
By placing changeable nanofabricated structures (wires, dots, etc.) on an
atom mirror one can design guiding and trapping potentials for atoms. These
potentials are similar to the electrostatic potentials which trap and guide
electrons in semiconductor quantum devices like quantum wires and quantum dots.
This technique will allow the fabrication of nanoscale atom optical devices.Comment: 6 pages, 3 figures, EPJ D in prin
Dephasing in two decoupled one-dimensional Bose-Einstein condensates and the subexponential decay of the interwell coherence
We provide a simple physical picture of the loss of coherence between two
coherently split one-dimensional Bose-Einstein condensates. The source of the
dephasing is identified with nonlinear corrections to the elementary excitation
energies in either of the two independent condensates. We retrieve the result
by Burkov, Lukin and Demler [Phys. Rev. Lett. 98, 200404 (2007)] on the
subexponential decay of the cocherence for the large time, however, the scaling
of the characteristic decoherence time differs.Comment: revtex4, no figure
Guiding Neutral Atoms with a Wire
We demonstrate guiding of cold neutral atoms along a current carrying wire.
Atoms either move in Kepler-like orbits around the wire or are guided in a
potential tube on the side of the wire which is created by applying an
additional homogeneous bias field. These atom guides are very versatile and
promising for applications in atom optics.Comment: 4 pages, 6 figures, submitted to PR
Rydberg Atoms in Magnetic Quadrupole Traps
We investigate the electronic structure and properties of Rydberg atoms
exposed to a magnetic quadrupole field. It is shown that the spatial as well as
generalized time reversal symmetries lead to a two-fold degeneracy of the
electronic states in the presence of the external field. A delicate interplay
between the Coulomb and magnetic interactions in the inhomogeneous field leads
to an unusual weak field splitting of the energy levels as well as complex
spatial patterns of the corresponding spin polarization density of individual
Rydberg states. Remarkably the magnetic quadrupole field induces a permanent
electric dipole moment of the atom.Comment: 8 pages, 5 figures, accepted for publication in EP
One-dimensional atomic superfluids as a model system for quantum thermodynamics
In this chapter we will present the one-dimensional (1d) quantum degenerate
Bose gas (1d superfluid) as a testbed to experimentally illustrate some of the
key aspects of quantum thermodynamics. Hard-core bosons in one-dimension are
described by the integrable Lieb-Lininger model. Realistic systems, as they can
be implemented, are only approximately integrable, and let us investigate the
cross over to 'thermalisation'. They show such fundamental properties as
pre-thermalisation, general Gibbs ensembles and light-cone like spreading of
de-coherence. On the other hand they are complex enough to illustrate that our
limited ability to measure only (local) few-body observables determines the
relevant description of the many-body system and its physics. One consequence
is the observation of quantum recurrences in systems with thousand of
interacting particles. The relaxation observed in 1D superfluids is universal
for a large class of many-body systems, those where the relevant physics can be
described by a set of 'long lived' collective modes. The time window where the
'close to integrable' dynamics can be observed is given by the 'lifetime' of
the quasi-particles associated with the collective modes. Based on these
observations one can view (in a quantum field theory sense) a many-body quantum
system at T=0 as 'vacuum' and its excitations as the system to experiment with.
This viewpoint leads to a new way to build thermal machines from the
quasi-particles in 1D superfluids. We will give examples of how to realise
these systems and point to a few interesting questions that might be addressed.Comment: 16 pages, 11 figures; Chapter of the upcoming book "Thermodynamics in
the Quantum Regime - Recent Progress and Outlook", eds. F. Binder, L. A.
Correa, C. Gogolin, J. Anders, and G. Adesso; comments welcom
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