Prof Arzhang Ardavan: Publications

Coherent state transfer between an electron- and nuclear spin in 15N@C60

(2010)

Authors:

Richard M Brown, Alexei M Tyryshkin, Kyriakos Porfyrakis, Erik M Gauger, Brendon W Lovett, Arzhang Ardavan, SA Lyon, G Andrew D Briggs, John JL Morton

Quantum interference between photo-excited states in a solid-state Mott insulator

Lasers and Electro Optics Quantum Electronics and Laser Science Conference 2010 Laser Science to Photonic Applications CLEO QELS 2010 (2010)

Authors:

S Wall, D Brida, SR Clark, HP Ehrke, D Jaksch, A Ardavan, S Bonora, H Uemura, Y Takahashi, T Hasegawa, H Okamoto, G Cerullo, A Cavalleri

Abstract:

By exciting with sub-10-fs 1.6-μm pulses the quasi-one-dimensional Mott insulator ETF2TCNQ, we observe prompt collapse of the Mott gap modulated by 24-THz oscillations of the gap, which are assigned to quantum interference between holon-doublon excitations. © 2010 Optical Society of America.

Storage of multiple coherent microwave excitations in an electron spin ensemble.

Phys Rev Lett 105:14 (2010) 140503

Authors:

Hua Wu, Richard E George, Janus H Wesenberg, Klaus Mølmer, David I Schuster, Robert J Schoelkopf, Kohei M Itoh, Arzhang Ardavan, John JL Morton, G Andrew D Briggs

Abstract:

Strong coupling between a microwave photon and electron spins, which could enable a long-lived quantum memory element for superconducting qubits, is possible using a large ensemble of spins. This represents an inefficient use of resources unless multiple photons, or qubits, can be orthogonally stored and retrieved. Here we employ holographic techniques to realize a coherent memory using a pulsed magnetic field gradient and demonstrate the storage and retrieval of up to 100 weak 10 GHz coherent excitations in collective states of an electron spin ensemble. We further show that such collective excitations in the electron spin can then be stored in nuclear spin states, which offer coherence times in excess of seconds.

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. © 2010 The American Physical Society.

Electron spin coherence in metallofullerenes: Y, Sc, and La@C82

Physical Review B Condensed Matter and Materials Physics 82:3 (2010)

Authors:

RM Brown, Y Ito, JH Warner, A Ardavan, H Shinohara, GAD Briggs, JJL Morton

Abstract:

Endohedral fullerenes encapsulating a spin-active atom or ion within a carbon cage offer a route to self-assembled arrays such as spin chains. In the case of metallofullerenes the charge transfer between the atom and the fullerene cage has been thought to limit the electron spin phase coherence time (T 2) to the order of a few microseconds. We study electron spin relaxation in several species of metallofullerene as a function of temperature and solvent environment, yielding a maximum T2 in deuterated o-terphenyl greater than 200 μs for Y, Sc, and La@C82. The mechanisms governing relaxation (T1, T2) arise from metal-cage vibrational modes, spin-orbit coupling and the nuclear spin environment. The T2 times are over 2 orders of magnitude longer than previously reported and consequently make metallofullerenes of interest in areas such as spin labeling, spintronics, and quantum computing. © 2010 The American Physical Society.

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