Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Acta Physica Polonica A

Carrier Spin Dephasing during Spin-Preserving Tunneling in Coupled Quantum Dots

Mateusz Krzykowski, Michał Gawełczyk, Paweł Machnikowski

Published Nov 1, 2016• 4 citations
Publisher

Abstract

In this contribution we study carrier tunneling in a system consisting of a pair of coupled quantum dots.We predict the presence of a spin dephasing channel in such a system, which is associated with a "welcher-weg" type of decoherence process occurring during carrier tunneling.In our model such a process is caused by a mismatch of g-factor values in two quantum dots in the presence of external magnetic field.This leads to a mismatch in spin Zeeman splitting between the dots and, in consequence, to the distinguishability of phonons emitted during the tunneling of carriers with opposite spins.Thus we demonstrate a process of spin dephasing without any direct spin-environment coupling present in the model.

DOI
10.12693/aphyspola.130.1165

Related papers

Controllable electron spin dephasing due to phonon state distinguishability in a coupled quantum dot system

Michał Gawełczyk, Mateusz Krzykowski, Krzysztof Gawarecki +1 more

We predict a spin pure dephasing channel in electron relaxation between states with unequal Zeeman splittings, exemplified by a spin-preserving electron tunneling between quantum dots in a magnetic field. The dephasing is caused by a mismatch in electron $g$ factors in the dots leading to distinguishability of phonons emitted during tunneling with opposite spins. Combining multiband $\mathbit{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{p}$ modeling and dynamical simulations via a master equation, we show that this fundamental effect of spin measurement effected by the phonon bath may be widely controlled by the size and composition of the dots or on demand via tuning of external fields. By comparing the numerically simulated degree of dephasing with the predictions of general theory based on distinguishability of environment states, we show that the proposed mechanism is the dominant phonon-related spin dephasing channel and may limit spin coherence time in tunnel-coupled structures at cryogenic temperatures.

arXiv:1707.06155•Physical review. B./Physical review. B•Aug 3, 2018•11 citations

Electron Spin Dephasing in a Double Quantum Dot Canceled via a Magnetic-Field Gradient

Michał Gawełczyk

Phonon-assisted tunneling of electrons between nonidentical quantum dots in a magnetic field has been recently shown to be affected by a spin pure dephasing.The process is due to the mismatch of the Zeeman splittings caused by the difference of effective electron g-factors in the two dots.Based on both analytical estimation and an accurate numerical modeling of a double quantum dot system, we show that this dephasing can be canceled by applying an appropriately tuned magnetic-field gradient that compensates for the built-in inequality of the Zeeman splittings.

Acta Physica Polonica A•Oct 1, 2018•1 citation

Indirect spin dephasing via charge-state decoherence in optical control schemes in quantum dots

Anna Grodecka, Paweł Machnikowski, Jens Förstner

We demonstrate that an optically driven spin of a carrier in a quantum dot undergoes indirect dephasing via conditional optically induced charge evolution even in the absence of any direct interaction between the spin and its environment. A generic model for the indirect dephasing with a three-component system with spin, charge, and reservoir is proposed. This indirect decoherence channel is studied for the optical spin manipulation in a quantum dot with a microscopic description of the charge-phonon interaction taking into account its non-Markovian nature.

arXiv:0811.2108•Physical Review A•Apr 23, 2009•4 citations

Spin-spin coupling in electrostatically coupled quantum dots

Mircea Trif, Vitaly N. Golovach, Daniel Loss

We study the spin-spin coupling between two single-electron quantum dots due to the Coulomb and spin-orbit interactions, in the absence of tunneling between the dots. We find an anisotropic $XY$ spin-spin interaction that is proportional to the Zeeman splitting produced by the external magnetic field. This interaction is studied both in the limit of weak and strong Coulomb repulsion with respect to the level spacing of the dot. The interaction is found to be a nonmonotonic function of interdot distance ${a}_{0}$ and external magnetic field and, moreover, vanishes for some special values of ${a}_{0}$ and/or magnetic field orientation. This mechanism thus provides a new way to generate and tune spin interaction between quantum dots. We propose a scheme to measure this spin-spin interaction based on the spin-relaxation-measurement technique.

arXiv:cond-mat/0608512•Physical Review B•Feb 7, 2007•50 citations

Two-spin dephasing by electron-phonon interaction in semiconductor double quantum dots

Xuedong Hu

We study electron-phonon interaction induced decoherence between two-electron singlet and triplet states in a semiconductor double quantum dot using a spin-boson model. We investigate the onset and time evolution of this dephasing, and study its dependence on quantum dot parameters such as dot size and double dot separations, as well as the host materials (GaAs and Si). At the short time limit, electron-phonon interaction only causes an incomplete initial Gaussian decay of the off-diagonal density matrix element in the singlet-triplet Hilbert space; a complete long-time exponential decay due to phonon relaxation would eventually dominate over two-spin decoherence. We analyze two-spin decoherence in both symmetric and biased double quantum dots, identifying their difference in electron-phonon coupling and the relevant consequences.

arXiv:1010.4093•Physical Review B•Apr 29, 2011•37 citations

Phonon-Induced Pure Dephasing of Two-Electron Spin States in Vertical Quantum Dot Molecules

Katarzyna Roszak, Paweł Machnikowski

Phonon-induced dephasing of two-electron spin states in two vertically stacked self-assembled GaAs/InGaAs quantum dots is studied.A pure dephasing process due to elastic phonon scattering is found to dominate at low temperatures.This process is independent of the spin-orbit coupling and does not require the presence of a magnetic field.It relies on interdot tunneling and the Pauli principle, which make the double quantum dot gate for spin based quantum computing possible, and therefore cannot be avoided.

Acta Physica Polonica A•Nov 1, 2009•1 citation
In this contribution we study carrier tunneling in a system consisting of a pair of coupled quantum dots.We predict the presence of a spin dephasing channel in such a system, which is associated with a "welcher-weg" type of decoherence process occurring during carrier tunneling.In our model such a process is caused by a mismatch of g-factor values in two quantum dots in the presence of external magnetic field.This leads to a mismatch in spin Zeeman splitting between the dots and, in consequence, to the distinguishability of phonons emitted during the tunneling of carriers with opposite spins.Thus we demonstrate a process of spin dephasing without any direct spin-environment coupling present in the model.
We predict a spin pure dephasing channel in electron relaxation between states with unequal Zeeman splittings, exemplified by a spin-preserving electron tunneling between quantum dots in a magnetic field. The dephasing is caused by a mismatch in electron ggg factors in the dots leading to distinguishability of phonons emitted during tunneling with opposite spins. Combining multiband $\mathbit{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{p}$ modeling and dynamical simulations via a master equation, we show that this fundamental effect of spin measurement effected by the phonon bath may be widely controlled by the size and composition of the dots or on demand via tuning of external fields. By comparing the numerically simulated degree of dephasing with the predictions of general theory based on distinguishability of environment states, we show that the proposed mechanism is the dominant phonon-related spin dephasing channel and may limit spin coherence time in tunnel-coupled structures at cryogenic temperatures.
Phonon-assisted tunneling of electrons between nonidentical quantum dots in a magnetic field has been recently shown to be affected by a spin pure dephasing.The process is due to the mismatch of the Zeeman splittings caused by the difference of effective electron g-factors in the two dots.Based on both analytical estimation and an accurate numerical modeling of a double quantum dot system, we show that this dephasing can be canceled by applying an appropriately tuned magnetic-field gradient that compensates for the built-in inequality of the Zeeman splittings.
We demonstrate that an optically driven spin of a carrier in a quantum dot undergoes indirect dephasing via conditional optically induced charge evolution even in the absence of any direct interaction between the spin and its environment. A generic model for the indirect dephasing with a three-component system with spin, charge, and reservoir is proposed. This indirect decoherence channel is studied for the optical spin manipulation in a quantum dot with a microscopic description of the charge-phonon interaction taking into account its non-Markovian nature.
We study the spin-spin coupling between two single-electron quantum dots due to the Coulomb and spin-orbit interactions, in the absence of tunneling between the dots. We find an anisotropic XYXYXY spin-spin interaction that is proportional to the Zeeman splitting produced by the external magnetic field. This interaction is studied both in the limit of weak and strong Coulomb repulsion with respect to the level spacing of the dot. The interaction is found to be a nonmonotonic function of interdot distance a0{a}_{0}a0​ and external magnetic field and, moreover, vanishes for some special values of a0{a}_{0}a0​ and/or magnetic field orientation. This mechanism thus provides a new way to generate and tune spin interaction between quantum dots. We propose a scheme to measure this spin-spin interaction based on the spin-relaxation-measurement technique.
We study electron-phonon interaction induced decoherence between two-electron singlet and triplet states in a semiconductor double quantum dot using a spin-boson model. We investigate the onset and time evolution of this dephasing, and study its dependence on quantum dot parameters such as dot size and double dot separations, as well as the host materials (GaAs and Si). At the short time limit, electron-phonon interaction only causes an incomplete initial Gaussian decay of the off-diagonal density matrix element in the singlet-triplet Hilbert space; a complete long-time exponential decay due to phonon relaxation would eventually dominate over two-spin decoherence. We analyze two-spin decoherence in both symmetric and biased double quantum dots, identifying their difference in electron-phonon coupling and the relevant consequences.
Phonon-induced dephasing of two-electron spin states in two vertically stacked self-assembled GaAs/InGaAs quantum dots is studied.A pure dephasing process due to elastic phonon scattering is found to dominate at low temperatures.This process is independent of the spin-orbit coupling and does not require the presence of a magnetic field.It relies on interdot tunneling and the Pauli principle, which make the double quantum dot gate for spin based quantum computing possible, and therefore cannot be avoided.