Theory of Nuclear Spin Dephasing and Relaxation by Optically Illuminated Nitrogen-Vacancy Center
Update: 2016-02-02 14:02:58      Author:

The electronic spin of the nitrogen-vacancy (NV) center in diamond and a few surrounding nuclear spins form a hybrid quantum register for applications in various quantum technologies such as quantum computation, communication, and nanoscale sensing. An important advantage of this solid-state quantum register is the long electron and nuclear spin coherence time in the dark and the capability of high-fidelity initialization and readout by optical illumination. However, the optically illuminated NV becomes a noisy environment that significantly shortens the coherence time (both the dephasing time T2 and relaxation time T1) of the nuclear spin qubits. In the past few years, this issue has been studied by many works, e.g., Dutt et al. [1] found the T2 of a strongly coupled 13C nuclear spin first increases and then saturates when the transverse magnetic field is decreased to zero. Dreau et al. [2] found the T1 of the 13C nuclear spin is also limited by optical illumination under a longitudinal magnetic field. Up to date, the understanding about these experimental results remains phenomenological and qualitative [3].



 Fig. 1: Comparison between our theory and experimentally measured T1 (left panel) from Ref. [2] and T2 (right panel) from Ref. [1].

In this year, Prof. Wen Yang and his group member bridge this gap between experimental observation and theoretical understanding by presenting a quantitative theory [4] that reveals the dependence of nuclear spin T1 and T2 on various experimentally measurable microscopic parameters. It not only provides a clear physical picture and quantitative explanation of the experimentally observed nuclear spin T1 over a wide range of magnetic field [2] (left panel of Fig. 1), but also identifies a hitherto undiscovered contribution to the nuclear spin T2 that is not suppressed even under saturated illumination and/or vanishing magnetic field. This provides a possible solution to the puzzling observation of nuclear spin dephasing in zero transverse magnetic field [1] (right panel of Fig. 1).



[1]      M. V. G. Dutt, L. Childress, L. Jiang, E. Togan, J. Maze, F. Jelezko, A. S. Zibrov, P. R. Hemmer, and M. D. Lukin, Science 316, 1312 (2007).

[2]      A. Dreau, P. Spinicelli, J. R. Maze, J. F. Roch, and V. Jacques, Phys. Rev. Lett. 110, 060502 (2013).

[3]      L. Jiang, M. V. G. Dutt, E. Togan, L. Childress, P. Cappellaro, J. M. Taylor, and M. D. Lukin, Phys. Rev. Lett. 100, 073001 (2008).

[4]      Ping Wang and Wen Yang, New J. Phys. 17, 113041 (2015).

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