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

arXiv:1306.5889 · Europhysics Letters (EPL)

Dynamical spin-spin coupling of quantum dots

Vahram L. Grigoryan, Jiang Xiao

Published Oct 1, 2013• 1 citation
arXivHTMLPDF

Abstract

We carried out a nested Schrieffer-Wolff transformation of an Anderson two-impurity Hamiltonian to study the spin-spin coupling between two dynamical quantum dots under the influence of rotating transverse magnetic field. As a result of the rotating field, we predict a novel Ising type spin-spin coupling mechanism between quantum dots, whose strength is tunable via the magnitude of the rotating field. Due to its dynamical origin, this new coupling mechanism is qualitatively different from the all existing static couplings such as RKKY, while the strength could be comparable to the strength of the RKKY coupling. The dynamical coupling with the intristic RKKY coupling enables to construct a four-level system of maximally entangled Bell states in a controllable manner.

DOI
10.1209/0295-5075/104/17008

Related papers

Entanglement dynamics of electron spins in quantum dots under a nonuniform magnetic field

Fengxue Zhou, Yihong Qi, Yueping Niu +3 more

We investigate entanglement of two coupled electron spins in quantum dots (QDs) in the presence of an inhomogeneous magnetic field. The important effects of the inhomogeneous field are discussed for the dynamics of entanglement. Due to the system’s symmetry, the inhomogeneity of the field is shown not to affect the evolution of entanglement for Φ-type Bell state while it plays a key role for Ψ-type Bell state. For the maximal entangled Bell states, the field is positive for the entanglement dynamics. The mean field can increase the entanglement revival for Φ-type Bell state while an inhomogeneous field can promote the entanglement revival for Ψ-type Bell state. For the unentangled initial states, the field is destructive for the entanglement generation induced by the coupling of the two spins.

Journal of the Korean Physical Society•Apr 1, 2012•0 citations

Tuning the Nonlocal Spin-Spin Interaction between Quantum Dots with a Magnetic Field

Gonzalo Usaj, Pablo Germán Lustemberg, C. A. Balseiro

We describe a device where the nonlocal spin-spin interaction between quantum dots (QDs) can be turned on and off with a small magnetic field. The setup consists of two QDs at the edge of two two-dimensional electron gases (2DEGs). The QDs' spins are coupled through a RKKY-like interaction mediated by the electrons in the 2DEGs. A magnetic field B(z) perpendicular to the plane of the 2DEG is used as a tuning parameter. When the cyclotron radius is commensurate with the interdot distance, the spin-spin interaction is amplified by a few orders of magnitude. The sign of the interaction is controlled by finely tuning B(z). Our setup allows for several dots to be coupled in a linear arrangement and it is not restricted to nearest-neighbor interaction.

arXiv:cond-mat/0407081•Physical Review Letters•Jan 27, 2005•17 citations

Controllable exchange coupling between two singlet-triplet qubits

Rui Li, Xuedong Hu, J. Q. You

We study controllable exchange coupling between two singlet-triplet qubits. We start from the original second quantized Hamiltonian of a quadruple quantum dot system and obtain the effective spin-spin interaction between the two qubits using the projection operator method. Under a strong uniform external magnetic field and an inhomogeneous local micromagnetic field, the effective interqubit coupling is of the Ising type, and the coupling strength can be expressed in terms of quantum dot parameters. Finally, we discuss how to generate various two-qubit operations using this controllable coupling, such as entanglement generation, and a controlled-not gate.

arXiv:1206.3112•Physical Review B•Nov 6, 2012•45 citations

Design and control of spin gates in two quantum-dot arrays

Gonzalo Usaj, C. A. Balseiro

We study the spin-spin interaction between quantum dots coupled through a two-dimensional electron gas with spin-orbit interaction. We show that the interplay between transverse electron focusing and spin-orbit coupling allows to dynamically change the symmetry of the effective spin-spin Hamiltonian. That is, the interaction can be changed from Ising-like to Heisenberg-like and vice versa. The sign and magnitude of the coupling constant can also be tuned.

arXiv:cond-mat/0506414•Applied Physics Letters•Mar 6, 2006•5 citations

Control of Kondo Quantum Dots arrays coupled to a Quantum Wire

J. Simonin

We analyze the interactions between two Kondo Quantum Dots connected to a Rashba-active Quantum Wire. We find that the Kondo-doublet interaction, at an inter-dot distance of the order of the wire Fermi length, is over an order of magnitude greater than the RKKY interaction. The effects induced on the Kondo-doublet interaction by the wire spin-orbit coupling can be used to control the Quantum Dots spin-spin correlation. These results imply that the widely used assumption that the RKKY is the dominant interaction between Anderson impurities must be revised.

arXiv:cond-mat/0607620•Jul 24, 2006•0 citations

Charge and spin qubits in interacting quantum dots coupled to Rashba-active leads

Grazia Di Bello, Fabrizio Pavan, Mattia Trama +3 more

We present a unified study of charge and spin qubits encoded in a single interacting quantum dot tunnel-coupled to Rashba fermionic leads. The dot is described by an Anderson impurity Hamiltonian with either repulsive or attractive local interactions and a magnetic field of arbitrary orientation. In the repulsive regime, a spin qubit is encoded in the singly occupied spin sector, whereas in the attractive regime, close to the degeneracy between the empty and doubly occupied configurations, these two states define a charge-qubit subspace. We combine a weak-coupling Lindblad master equation in the Markovian secular limit with numerically controlled matrix-product-state simulations of the full dot-reservoir system. In equilibrium, we identify magnetic pair breaking in the attractive regime and a weak Rashba-induced magnetic anisotropy when the magnetic field is rotated relative to the spin-orbit axis. In the dynamical regime, relaxation and decoherence are controlled by the energetic gap between the logical manifold and nearby leakage states, and are further enhanced by Rashba-dependent tunneling. These findings show that even a minimal Anderson-impurity description captures key ingredients for coherent spin and charge qubits: the energetic structure of leakage states and spin-orbit-dependent dot-lead hybridization.

cond-mat.mes-hallCross-listedarXiv:2609.27648•Sep 24, 2026•0 citations
We carried out a nested Schrieffer-Wolff transformation of an Anderson two-impurity Hamiltonian to study the spin-spin coupling between two dynamical quantum dots under the influence of rotating transverse magnetic field. As a result of the rotating field, we predict a novel Ising type spin-spin coupling mechanism between quantum dots, whose strength is tunable via the magnitude of the rotating field. Due to its dynamical origin, this new coupling mechanism is qualitatively different from the all existing static couplings such as RKKY, while the strength could be comparable to the strength of the RKKY coupling. The dynamical coupling with the intristic RKKY coupling enables to construct a four-level system of maximally entangled Bell states in a controllable manner.
We investigate entanglement of two coupled electron spins in quantum dots (QDs) in the presence of an inhomogeneous magnetic field. The important effects of the inhomogeneous field are discussed for the dynamics of entanglement. Due to the system’s symmetry, the inhomogeneity of the field is shown not to affect the evolution of entanglement for Φ-type Bell state while it plays a key role for Ψ-type Bell state. For the maximal entangled Bell states, the field is positive for the entanglement dynamics. The mean field can increase the entanglement revival for Φ-type Bell state while an inhomogeneous field can promote the entanglement revival for Ψ-type Bell state. For the unentangled initial states, the field is destructive for the entanglement generation induced by the coupling of the two spins.
We describe a device where the nonlocal spin-spin interaction between quantum dots (QDs) can be turned on and off with a small magnetic field. The setup consists of two QDs at the edge of two two-dimensional electron gases (2DEGs). The QDs' spins are coupled through a RKKY-like interaction mediated by the electrons in the 2DEGs. A magnetic field B(z) perpendicular to the plane of the 2DEG is used as a tuning parameter. When the cyclotron radius is commensurate with the interdot distance, the spin-spin interaction is amplified by a few orders of magnitude. The sign of the interaction is controlled by finely tuning B(z). Our setup allows for several dots to be coupled in a linear arrangement and it is not restricted to nearest-neighbor interaction.
We study controllable exchange coupling between two singlet-triplet qubits. We start from the original second quantized Hamiltonian of a quadruple quantum dot system and obtain the effective spin-spin interaction between the two qubits using the projection operator method. Under a strong uniform external magnetic field and an inhomogeneous local micromagnetic field, the effective interqubit coupling is of the Ising type, and the coupling strength can be expressed in terms of quantum dot parameters. Finally, we discuss how to generate various two-qubit operations using this controllable coupling, such as entanglement generation, and a controlled-not gate.
We analyze the interactions between two Kondo Quantum Dots connected to a Rashba-active Quantum Wire. We find that the Kondo-doublet interaction, at an inter-dot distance of the order of the wire Fermi length, is over an order of magnitude greater than the RKKY interaction. The effects induced on the Kondo-doublet interaction by the wire spin-orbit coupling can be used to control the Quantum Dots spin-spin correlation. These results imply that the widely used assumption that the RKKY is the dominant interaction between Anderson impurities must be revised.
We present a unified study of charge and spin qubits encoded in a single interacting quantum dot tunnel-coupled to Rashba fermionic leads. The dot is described by an Anderson impurity Hamiltonian with either repulsive or attractive local interactions and a magnetic field of arbitrary orientation. In the repulsive regime, a spin qubit is encoded in the singly occupied spin sector, whereas in the attractive regime, close to the degeneracy between the empty and doubly occupied configurations, these two states define a charge-qubit subspace. We combine a weak-coupling Lindblad master equation in the Markovian secular limit with numerically controlled matrix-product-state simulations of the full dot-reservoir system. In equilibrium, we identify magnetic pair breaking in the attractive regime and a weak Rashba-induced magnetic anisotropy when the magnetic field is rotated relative to the spin-orbit axis. In the dynamical regime, relaxation and decoherence are controlled by the energetic gap between the logical manifold and nearby leakage states, and are further enhanced by Rashba-dependent tunneling. These findings show that even a minimal Anderson-impurity description captures key ingredients for coherent spin and charge qubits: the energetic structure of leakage states and spin-orbit-dependent dot-lead hybridization.