1,960 research outputs found
Implementation of a three-qubit quantum error correction code in a cavity-QED setup
The correction of errors is of fundamental importance for the development of
contemporary computing devices and of robust communication protocols. In this
paper we propose a scheme for the implementation of the three-qubit quantum
repetition code, exploiting the interaction of Rydberg atoms with the quantized
mode of a microwave cavity field. Quantum information is encoded within two
circular Rydberg states of the atoms and encoding and decoding process are
realized within two separate microwave cavities. We show that errors due to
phase noise fluctuations could be efficiently corrected using a
state-of-the-art apparatus.Comment: 9 pages, 5 figures. This is v2. Some misprints corrected, conclusions
section extended, refs added. Accepted for publication on PR
Two-photon driven nonlinear dynamics and entanglement of an atom in a non uniform cavity
In this paper we study the dynamics in the general case for a Tavis Cummings
atom in a non-uniform cavity. In addition to the dynamical Stark shift, the
center-of-mass motion of the atom and the recoil effect are considered in both
- the weak and the strong cavity atom coupling regimes. It is shown that the
spatial motion of the atom inside the cavity in the resonant case leads to a
transition between topologically different solutions. This effect is manifested
by a singularity in the inter-level transition spectrum. In the non-resonant
case, the spatial motion of the atom leads to a switching of the spin
orientation. In both effects, the key factor is the relation between the values
of the Stark shift and the cavity field coupling constant. We also investigate
the entanglement of an atom in the cavity with the radiation field. It is shown
that the entanglement between the atom and the field, usually quantified in
terms of purity, decreases with increasing the Stark shift.Comment: to appear in Phys. Rev.
Quantum Memories. A Review based on the European Integrated Project "Qubit Applications (QAP)"
We perform a review of various approaches to the implementation of quantum
memories, with an emphasis on activities within the quantum memory sub-project
of the EU Integrated Project "Qubit Applications". We begin with a brief
overview over different applications for quantum memories and different types
of quantum memories. We discuss the most important criteria for assessing
quantum memory performance and the most important physical requirements. Then
we review the different approaches represented in "Qubit Applications" in some
detail. They include solid-state atomic ensembles, NV centers, quantum dots,
single atoms, atomic gases and optical phonons in diamond. We compare the
different approaches using the discussed criteria.Comment: 22 pages, 12 figure
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