Long-time electron spin storage via dynamical suppression of hyperfine-induced decoherence in a quantum dot

TitleLong-time electron spin storage via dynamical suppression of hyperfine-induced decoherence in a quantum dot
Publication TypeJournal Article
Year of Publication2008
AuthorsZhang WX, Konstantinidis NP, Dobrovitski VV, Harmon BN, Santos LF, Viola L
Journal TitlePhysical Review B
Volume77
Pages125336
Date PublishedMar
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberISI:000254543000108
KeywordsCOMPUTATION, CONVERGENCE, COUPLED ELECTRON, ENTANGLEMENT, magnetization, MAGNUS EXPANSION, NANOSTRUCTURES, NUCLEI, relaxation, systems
Abstract

The coherence time of an electron spin decohered by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron to suitable dynamical decoupling sequences. We analyze the performance of high-level decoupling protocols by using a combination of analytical and exact numerical methods, and by paying special attention to the regimes of large interpulse delays and long-time dynamics, which are outside the reach of standard average Hamiltonian theory descriptions. We demonstrate that dynamical decoupling can remain efficient far beyond its formal domain of applicability, and find that a protocol exploiting concatenated design provides best performance for this system in the relevant parameter range. In situations where the initial electron state is known, protocols able to completely freeze decoherence at long times are constructed and characterized. The impact of system and control nonidealities is also assessed, including the effect of intrabath dipolar interaction, magnetic field bias and bath polarization, as well as systematic pulse imperfections. While small bias field and small bath polarization degrade the decoupling fidelity, enhanced performance and temporal modulation result from strong applied fields and high polarizations. Overall, we find that if the relative errors of the control pulse flip angles do not exceed 3%, decoupling protocols can still prolong the coherence time by up to 2 orders of magnitude.

DOI10.1103/PhysRevB.77.125336
Alternate JournalPhys. Rev. B