dorsal/arxiv
View SchemaIntroduction to NMR Quantum Information Processing
| Authors | R. Laflamme, E. Knill, D. G. Cory, E. M. Fortunato, T. Havel, C. Miquel, R. Martinez, C. Negrevergne, G. Ortiz, M. A. Pravia, Y. Sharf, S. Sinha, R. Somma, L. Viola |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0207172 |
| URL | https://arxiv.org/abs/quant-ph/0207172 |
Abstract
After a general introduction to nuclear magnetic resonance (NMR), we give the basics of implementing quantum algorithms. We describe how qubits are realized and controlled with RF pulses, their internal interactions, and gradient fields. A peculiarity of NMR is that the internal interactions (given by the internal Hamiltonian) are always on. We discuss how they can be effectively turned off with the help of a standard NMR method called ``refocusing''. Liquid state NMR experiments are done at room temperature, leading to an extremely mixed (that is, nearly random) initial state. Despite this high degree of randomness, it is possible to investigate QIP because the relaxation time (the time scale over which useful signal from a computation is lost) is sufficiently long. We explain how this feature leads to the crucial ability of simulating a pure (non-random) state by using ``pseudopure'' states. We discuss how the ``answer'' provided by a computation is obtained by measurement and how this measurement differs from the ideal, projective measurement of QIP. We then give implementations of some simple quantum algorithms with a typical experimental result. We conclude with a discussion of what we have learned from NMR QIP so far and what the prospects for future NMR QIP experiments are.
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"abstract": "After a general introduction to nuclear magnetic resonance (NMR), we give the\nbasics of implementing quantum algorithms. We describe how qubits are realized\nand controlled with RF pulses, their internal interactions, and gradient\nfields. A peculiarity of NMR is that the internal interactions (given by the\ninternal Hamiltonian) are always on. We discuss how they can be effectively\nturned off with the help of a standard NMR method called ``refocusing\u0027\u0027. Liquid\nstate NMR experiments are done at room temperature, leading to an extremely\nmixed (that is, nearly random) initial state. Despite this high degree of\nrandomness, it is possible to investigate QIP because the relaxation time (the\ntime scale over which useful signal from a computation is lost) is sufficiently\nlong. We explain how this feature leads to the crucial ability of simulating a\npure (non-random) state by using ``pseudopure\u0027\u0027 states. We discuss how the\n``answer\u0027\u0027 provided by a computation is obtained by measurement and how this\nmeasurement differs from the ideal, projective measurement of QIP. We then give\nimplementations of some simple quantum algorithms with a typical experimental\nresult. We conclude with a discussion of what we have learned from NMR QIP so\nfar and what the prospects for future NMR QIP experiments are.",
"arxiv_id": "quant-ph/0207172",
"authors": [
"R. Laflamme",
"E. Knill",
"D. G. Cory",
"E. M. Fortunato",
"T. Havel",
"C. Miquel",
"R. Martinez",
"C. Negrevergne",
"G. Ortiz",
"M. A. Pravia",
"Y. Sharf",
"S. Sinha",
"R. Somma",
"L. Viola"
],
"categories": [
"quant-ph"
],
"title": "Introduction to NMR Quantum Information Processing",
"url": "https://arxiv.org/abs/quant-ph/0207172"
},
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