Physics – Condensed Matter – Mesoscale and Nanoscale Physics
Scientific paper
2012-04-12
Physics
Condensed Matter
Mesoscale and Nanoscale Physics
25 pages, 26 figures
Scientific paper
The central spin decoherence problem has been researched for over 50 years in the context of both nuclear magnetic resonance and electron spin resonance. Until recently, theoretical models have employed phenomenological stochastic descriptions of the bath-induced noise. During the last few years, cluster expansion methods have provided a microscopic, quantum theory to study the spectral diffusion of a central spin. These methods have proven to be very accurate and efficient for problems of nuclear-induced electron spin decoherence in which hyperfine interactions with the central electron spin are much stronger than dipolar interactions among the nuclei. We provide an in-depth study of central spin decoherence for a canonical scale-invariant all-dipolar spin system. We show how cluster methods may be adapted to treat this problem in which central and bath spin interactions are of comparable strength. Our extensive numerical work shows that a properly modified cluster theory is convergent for this problem even as simple perturbative arguments begin to break down. By treating clusters in the presence of energy detunings due to the long-range (diagonal) dipolar interactions of the surrounding environment and carefully avaraging the effects over different spin states, we find that the nontrivial flip-flop dynamics among the spins becomes effectively localized by disorder in the energy splittings of the spins. This localization effect allows for a robust calculation of the spin echo signal in a dipolarly-coupled bath of spins of the same kind, while considering clusters of no more than 6 spins. We connect these microscopic calculation results to the existing stochastic models. We furthermore present calculations for a series of related problems of interest for candidate solid state quantum bits including donors and quantum dots in silicon as well as nitrogen-vacancy centers in diamond.
Carroll Malcolm S.
Cywinski Lukasz
Sarma Sankar Das
Witzel Wayne M.
No associations
LandOfFree
Quantum Decoherence of the Central Spin in a Sparse System of Dipolar Coupled Spins does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Quantum Decoherence of the Central Spin in a Sparse System of Dipolar Coupled Spins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quantum Decoherence of the Central Spin in a Sparse System of Dipolar Coupled Spins will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-142837