Disorder-induced valley-orbit hybrid states in Si quantum dots
نویسندگان
چکیده
Quantum dots in silicon are promising candidates for the implementation of solid-state quantum information processing. It is important to understand the effects of the multiple conduction band valleys of silicon on the properties of these devices. Here we present a systematic effective mass theory of valley-orbit coupling in disordered silicon systems. This theory reveals valley-orbit hybridization effects that are detrimental for storing quantum information in the valley degree of freedom, including nonvanishing dipole matrix elements between valley states and altered intervalley tunneling.
منابع مشابه
Theory of valley-orbit coupling in a Si/SiGe quantum dot
Electron states are studied for quantum dots in a strained Si quantum well, taking into account both valley and orbital physics. Realistic geometries are considered, including circular and elliptical dot shapes, parallel and perpendicular magnetic fields, and most importantly for valley coupling the small local tilt of the quantum-well interface away from the crystallographic axes. In absence o...
متن کاملTwo-electron dephasing in single Si and GaAs quantum dots
We study the dephasing of two-electron states in a single quantum dot in both GaAs and Si. We investigate dephasing induced by electron-phonon coupling and by charge noise analytically for pure orbital excitations in GaAs and Si, as well as for pure valley excitations in Si. In GaAs, polar optical phonons give rise to the most important contribution, leading to a typical dephasing rate of ∼5.9 ...
متن کاملSpin-Orbit Coupling, Quantum Dots, and Qubits in Monolayer Transition Metal Dichalcogenides
We derive an effective Hamiltonian that describes the dynamics of electrons in the conduction band of monolayer transition metal dichalcogenides (TMDC) in the presence of perpendicular electric and magnetic fields. We discuss in detail both the intrinsic and the Bychkov-Rashba spin-orbit coupling induced by an external electric field. We point out interesting differences in the spin-split condu...
متن کاملDephasing and hyperfine interaction in carbon nanotube double quantum dots: The clean limit
We consider theoretically 13C-hyperfine interaction-induced dephasing in carbon nanotubes double quantum dots with curvature-induced spin-orbit coupling. For two electrons initially occupying a single dot, we calculate the average return probability after separation into the two dots, which have random nuclear spin configurations. We focus on the long-time saturation value of the return probabi...
متن کاملSpin-valley blockade in carbon nanotube double quantum dots
We present a theoretical study of the Pauli or spin-valley blockade for double quantum dots in semiconducting carbon nanotubes. In our model, we take into account the following characteristic features of carbon nanotubes: i fourfold spin and valley degeneracy of the quantum-dot levels, ii the intrinsic spin-orbit interaction which is enhanced by the tube curvature, and iii valley mixing due to ...
متن کامل