%0 Book Section
%B Quantum Information Processing
%D 2005
%T Entanglement Properties of Composite Quantum Systems
%A K. Eckert
%A O. Guehne
%A F. Hulpke
%A P. Hyllus
%A J. Korbicz
%A J. Mompart
%A D. Bruss
%A M. Lewenstein
%A A. Sanpera
%E T. Beth
%E G. Leuchs
%X We present here an overview of our work concerning entanglement properties of composite quantum systems. The characterization of entanglement, i.e. the possibility to assert if a given quantum state is entangled with others and how much entangled it is, remains one of the most fundamental open questions in quantum information theory. We discuss our recent results related to the problem of separability and distillability for distinguishable particles, employing the tool of witness operators. Finally, we also state our results concerning quantum correlations for indistinguishable particles.
%B Quantum Information Processing
%I BLACKWELL SCIENCE PUBL
%C OSNEY MEAD, OXFORD OX2 0EL, ENGLAND
%P 83-99
%@ 978-3-52760-600-9
%9 {Article; Book Chapter}
%R 10.1002/3527606009.ch7
%0 Journal Article
%J Phys. Rev. A
%D 2002
%T Quantum computing in optical microtraps based on the motional states of neutral atoms
%A K. Eckert
%A J. Mompart
%A X. X. Yi
%A J. Schliemann
%A D. Bruss
%A G. Birkl
%A M. Lewenstein
%X We investigate quantum computation with neutral atoms in optical microtraps where the qubit is implemented in the motional states of the atoms, i.e., in the two lowest vibrational states of each trap. The quantum gate operation is performed by adiabatically approaching two traps and allowing tunneling and cold collisions to take place. We demonstrate the capability of this scheme to realize a square root of swap gate, and address the problem of double occupation and excitation to other unwanted states. We expand the two-particle wave function in an orthonormal basis and analyze quantum correlations throughout the whole gate process. Fidelity of the gate operation is evaluated as a function of the degree of adiabaticity in moving the traps. Simulations are based on rubidium atoms in state-of-the-art optical microtraps with quantum gate realizations in the few tens of milliseconds duration range.
%B Phys. Rev. A
%I American Physical Society
%V 66
%P 042317
%8 Oct
%U http://link.aps.org/doi/10.1103/PhysRevA.66.042317
%R 10.1103/PhysRevA.66.042317