%0 Journal Article
%J Phys. Rev. Lett.
%D 2007
%T Trapped Ion Chain as a Neural Network: Error Resistant Quantum Computation
%A M. Pons
%A V. Ahufinger
%A C. Wunderlich
%A A. Sanpera
%A S. Braungardt
%A A. Sen(De)
%A U. Sen
%A M. Lewenstein
%X We demonstrate the possibility of realizing a neural network in a chain of trapped ions with induced long range interactions. Such models permit one to store information distributed over the whole system. The storage capacity of such a network, which depends on the phonon spectrum of the system, can be controlled by changing the external trapping potential. We analyze the implementation of error resistant universal quantum information processing in such systems.
%B Phys. Rev. Lett.
%I American Physical Society
%V 98
%P 023003
%8 Jan
%U http://link.aps.org/doi/10.1103/PhysRevLett.98.023003
%R 10.1103/PhysRevLett.98.023003
%0 Journal Article
%J Advances in Physics
%D 2007
%T Ultracold atomic gases in optical lattices: mimicking condensed matter physics and beyond
%A M. Lewenstein
%A A. Sanpera
%A V. Ahufinger
%A B. Damski
%A A. Sen(De)
%A U. Sen
%K disordered systems
%K frustrated systems
%K Hubbard models
%K quantum information
%K spinor gases
%K Ultracold atomic and molecular gases
%X We review recent developments in the physics of ultracold atomic and molecular gases in optical lattices. Such systems are nearly perfect realisations of various kinds of Hubbard models, and as such may very well serve to mimic condensed matter phenomena. We show how these systems may be employed as quantum simulators to answer some challenging open questions of condensed matter, and even high energy physics. After a short presentation of the models and the methods of treatment of such systems, we discuss in detail, which challenges of condensed matter physics can be addressed with (i) disordered ultracold lattice gases, (ii) frustrated ultracold gases, (iii) spinor lattice gases, (iv) lattice gases in ``artificial'' magnetic fields, and, last but not least, (v) quantum information processing in lattice gases. For completeness, also some recent progress related to the above topics with trapped cold gases will be discussed.
%B Advances in Physics
%I {TAYLOR & FRANCIS LTD}
%C {4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}
%V 56
%P 243-379
%R 10.1080/00018730701223200
%0 Journal Article
%J Phys. Rev. A
%D 2006
%T Quantum-information processing in disordered and complex quantum systems
%A A. Sen(De)
%A U. Sen
%A V. Ahufinger
%A H. J. Briegel
%A A. Sanpera
%A M. Lewenstein
%X We study quantum information processing in complex disordered many body systems that can be implemented by using lattices of ultracold atomic gases and trapped ions. We demonstrate, first in the short range case, the generation of entanglement and the local realization of quantum gates in a disordered magnetic model describing a quantum spin glass. We show that in this case it is possible to achieve fidelities of quantum gates higher than in the classical case. Complex systems with long range interactions, such as ions chains or dipolar atomic gases, can be used to model neural network Hamiltonians. For such systems, where both long range interactions and disorder appear, it is possible to generate long range bipartite entanglement. We provide an efficient analytical method to calculate the time evolution of a given initial state, which in turn allows us to calculate its quantum correlations.
%B Phys. Rev. A
%I American Physical Society
%V 74
%P 062309
%8 Dec
%U http://link.aps.org/doi/10.1103/PhysRevA.74.062309
%R 10.1103/PhysRevA.74.062309
%0 Conference Paper
%B Laser Spectroscopy
%D 2005
%T Disordered complex systems using cold gases and trapped ions
%A A. Sen(De)
%A U. Sen
%A M. Lewenstein
%A V. Ahufinger
%A M. Pons
%A A. Sanpera
%E E. A. Hinds
%E A. Ferguson
%E E. Riis
%X We report our research on disordered complex systems using cold gases and trapped ions and address the possibility of using complex systems for quantum information processing. Two simple paradigmatic models of disordered complex systems are here revisited. The first one corresponds to a short range disordered Ising Hamiltonian (spin glasses) which can be implemented with a bose-fermi (bose-bose) mixture in a disordered optical lattice. The second model we address here is a long range disordered Hamiltonian characteristic of neural networks (Hopfield model) which can be implemented in a chain of trapped ions with appropriately designed interactions.
%B Laser Spectroscopy
%C PO BOX 128 FARRER RD, SINGAPORE 9128, SINGAPORE
%P {158-166}
%@ 981-256-659-7
%9 {Proceedings Paper}