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Quantum information processing by NMR using a 5-qubit system formed by dipolar coupled spins in an oriented molecule

Das, Ranabir and Bhattacharyya, Rangeet and Kumar, Anil (2004) Quantum information processing by NMR using a 5-qubit system formed by dipolar coupled spins in an oriented molecule. In: Journal of Magnetic Resonance, 170 (2). pp. 310-321.


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Quantum Information processing by NMR with small number of qubits is well established. Scaling to higher number of qubits is hindered by two major requirements (i) mutual coupling among qubits and (ii) qubit addressability. It has been demonstrated that mutual coupling can be increased by using residual dipolar couplings among spins by orienting the spin system in a liquid crystalline matrix. In such a case, the heteronuclear spins are weakly coupled but the homonuclear spins become strongly coupled. In such circumstances, the strongly coupled spins can no longer be treated as qubits. However, it has been demonstrated elsewhere, that the $2^N$ energy levels of a strongly coupled N spin-1/2 system can be treated as an N-qubit system. For this purpose the various transitions have to be identified to well defined energy levels. This paper consists of two parts. In the first part, the energy level diagram of a heteronuclear 5-spin system is obtained by using a newly developed heteronuclear z-cosy (HET-Z-COSY) experiment. In the second part, implementation of logic gates, preparation of pseudopure states, creation of entanglement and entanglement transfer is demonstrated, validating the use of such systems for quantum information processing.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Elsevier Science.
Keywords: Quantum information processing;NMR;Liquid crystal
Department/Centre: Division of Chemical Sciences > Sophisticated Instruments Facility (Continued as NMR Research Centre)
Division of Physical & Mathematical Sciences > Physics
Depositing User: Ranabir Das
Date Deposited: 01 Mar 2005
Last Modified: 19 Sep 2010 04:18
URI: http://eprints.iisc.ac.in/id/eprint/2852

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