NMR quantum computing

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Reply to Comment on Spin-selective reactions of radical pairs act as quantum measurements

ArXiv 1104.0604 (2011)

Authors:

JA Jones, Kiminori Maeda, UE Steiner, PJ Hore

Abstract:

In his Comment on a recent paper by two of us Kominis claims that the recently proposed quantum measurement model for spin-selective reactions of radical pairs leads to ambiguous predictions in a simple case. Here we show that this claim is based on a confusion between the unreacted and unrecombined portions of the radical pairs, and to an incorrect interpretation of the improper density matrices used in both our model and the conventional Haberkorn model of such reactions. We further show that if this error is corrected then the supposed ambiguity is resolved.

Reaction operators for spin-selective chemical reactions of radical pairs

(2011)

Authors:

Jonathan A Jones, Kiminori Maeda, Peter J Hore

Reaction operators for spin-selective chemical reactions of radical pairs

ArXiv 1103.5875 (2011)

Authors:

Jonathan A Jones, Kiminori Maeda, Peter J Hore

Abstract:

Spin-selective reactions of radical pairs have traditionally been modelled theoretically by adding phenomenological rate equations to the quantum mechanical equation of motion of the radical pair spin density matrix. More recently an alternative set of rate expressions, based on a quantum measurement approach, has been suggested. Here we show how these two reaction operators can be seen as limiting cases of a more general reaction scheme.

Quantum Computing with NMR

(2010)

Magnetic field sensors using 13-spin cat states

Physical Review A - Atomic, Molecular, and Optical Physics 82:2 (2010)

Authors:

S Simmons, JA Jones, SD Karlen, A Ardavan, JJL Morton

Abstract:

Measurement devices could benefit from entangled correlations to yield a measurement sensitivity approaching the physical Heisenberg limit. Building upon previous magnetometric work using pseudoentangled spin states in solution-state NMR, we present two conceptual advancements to better prepare and interpret the pseudoentanglement resource. We apply these to a 13-spin cat state to measure the local magnetic field with a 12.2 sensitivity increase over an equivalent number of isolated spins. 漏 2010 The American Physical Society.