Electron spin dephasing due to hyperfine-mediated interactions in the nuclear bath

Łukasz Cywiński, Wayne M. Witzel, S. Das Sarma

Daniela Pagliero, Pablo R. Zangara, Jacob Henshaw +5 more

C magnetic resonance signal. Unexpectedly, we find good thermal contact throughout the nuclear spin bath, virtually independent of the hyperfine coupling strength, which we attribute to effective carbon-carbon interactions mediated by the electronic spin ensemble. In particular, observations across the full range of hyperfine couplings indicate the nuclear spin diffusion constant takes values up to two orders of magnitude greater than that expected from homo-nuclear spin couplings.

Ren‐Bao Liu

Rui Li

We theoretically investigate the dephasing of a central spin-1 model. An interesting mechanism of spin decoherence is found with this model, namely, hyperfine mediated spectral diffusion. This mechanism contains the features of both the dipolar-interactions-induced spectral diffusion and the hyperfine mediated interactions. We also find an anomalous magnetic field dependence of decoherence, which is caused by the competition between crystal field splitting and Zeeman splitting of the central spin. As the external magnetic field increases, in the V type level structure regime, the decoherence rate becomes much stronger; while in the cascade type level structure regime, just like localized electron spin in quantum dots, the decoherence rate becomes much weaker.

Nan Zhao, Wei Hua Yang, Sai-Wah Ho +5 more

Marko J. Rančić, Guido Burkard

We theoretically study the interplay of spin-orbit and hyperfine interactions in dynamical nuclear polarization in two-electron semiconductor double quantum dots near the singlet-triplet ($S\ensuremath{-}{T}_{+}$) anticrossing. The goal of the scheme under study is to extend the singlet-triplet ($S\ensuremath{-}{T}_{0}$) qubit decoherence time ${T}_{2}^{*}$ by dynamically transferring the polarization from the electron spins to the nuclear spins. This polarization transfer is achieved by cycling the electron spins over the $S\ensuremath{-}{T}_{+}$ anticrossing. Here, we investigate, both quantitatively and qualitatively, how this hyperfine-mediated dynamical polarization transfer is influenced by the Rashba and Dresselhaus spin-orbit interaction. In addition to ${T}_{2}^{*}$, we determine the singlet return probability ${P}_{s}$, a quantity that can be measured in experiments. Our results suggest that the spin-orbit interaction establishes a mechanism that can polarize the nuclear spins in the direction opposite to that of hyperfine-mediated nuclear spin polarization. In materials with relatively strong spin-orbit coupling, this interplay of spin-orbit and hyperfine-mediated nuclear spin polarizations prevents any notable increase in the $S\ensuremath{-}{T}_{0}$ qubit decoherence time ${T}_{2}^{*}$.