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

Abstract

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.

23 pages, 8 figures

References in corpus (4)

• Preparation of pseudopure state in a cluster of dipolar-coupled spins with "unresolved" spectrum
• Implementation of Conditional Phase Shift gate for Quantum Information Processing by NMR, using Transition-selective pulses
• Search for optimum labeling schemes in qubit systems for Quantum Information processing by NMR
• Quantum Information Processing by NMR using strongly coupled spins

Cited by in corpus (8)

• Quantum Computing with NMR
• A solid-state NMR three-qubit homonuclear system for quantum information processing: control and characterization
• Simulation of mirror inversion of quantum states in an XY spin chain using NMR
• Geometric quantum computation using fictitious spin- 1/2 subspaces of strongly dipolar coupled nuclear spins
• Use of non-adiabatic geometric phase for quantum computing by nuclear magnetic resonance
• Controlling NMR spin systems for quantum computation
• Implementation of Liouville space search algorithm on strongly dipolar coupled nuclear spins
• Generation and Detection of Quantum Correlations and Entanglement on a Spin-Based Quantum Information Processor