Quantum spin dynamics

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A new mechanism for electron spin echo envelope modulation

Journal of Chemical Physics 122:17 (2005)

Authors:

JJL Morton, AM Tyryshkin, A Ardavan, K Porfyrakis, SA Lyon, GAD Briggs

Abstract:

Electron spin echo envelope modulation (ESEEM) has been observed for the first time from a coupled heterospin pair of electron and nucleus in liquid solution. Previously, modulation effects in spin-echo experiments have only been described in liquid solutions for a coupled pair of homonuclear spins in nuclear magnetic resonance or a pair of resonant electron spins in electron paramagnetic resonance. We observe low-frequency ESEEM (26 and 52 kHz) due to a new mechanism present for any electron spin with S>12 that is hyperfine coupled to a nuclear spin. In our case these are electron spin (S=32) and nuclear spin (I=1) in the endohedral fullerene N@ C60. The modulation is shown to arise from second-order effects in the isotropic hyperfine coupling of an electron and N14 nucleus. © 2005 American Institute of Physics.
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High Fidelity Single Qubit Operations using Pulsed EPR

(2005)

Authors:

John JL Morton, Alexei M Tyryshkin, Arzhang Ardavan, Kyriakos Porfyrakis, SA Lyon, G Andrew D Briggs
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Electron paramagnetic resonance studies of the high-spin molecule Cr10 (OMe) 20 (O2 CCMe3) 10

Applied Physics Letters 86:3 (2005) 1-3

Authors:

S Sharmin, A Ardavan, SJ Blundell, AI Coldea, EJL Mcinnes, D Low

Abstract:

We report millimeter-wave magneto-optical measurements on the high-spin molecule, Cr10 (OMe) 20 (O2 CCMe3) 10. The dependence of the electron paramagnetic resonance as a function of orientation and temperature demonstrates that this compound behaves as a single molecule magnet, and exhibits one of the smallest zero-field splittings (D=-0.045±0.004 K) yet reported for such a system. © 2005 American Institute of Physics.
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Chemical reactions inside single-walled carbon nano test-tubes

Chemical Communications (2005) 37-39

Authors:

DA Britz, AN Khlobystov, K Porfyrakis, A Ardavan, GAD Briggs

Abstract:

We report the application of SWNTs as templates for forming covalent polymeric chains from C60O reacting inside SWNTs; the resulting peapod polymer topology is different from the bulk polymer in that it is linear and unbranched.
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Measuring errors in single-qubit rotations by pulsed electron paramagnetic resonance

Physical Review A Atomic Molecular and Optical Physics 71:1 (2005)

Authors:

JJL Morton, AM Tyryshkin, A Ardavan, K Porfyrakis, SA Lyon, GAD Briggs

Abstract:

The ability to measure and reduce systematic errors in single-qubit logic gates is crucial when evaluating quantum computing implementations. We describe pulsed electron paramagnetic resonance (EPR) sequences that can be used to measure precisely even small systematic errors in rotations of electron-spin-based qubits. Using these sequences we obtain values for errors in the rotation angle and axis for single-qubit rotations using a commercial EPR spectrometer. We conclude that errors in qubit operations by pulsed EPR are not limiting factors in the implementation of electron-spin-based quantum computers. © 2005 The American Physical Society.
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