Electron spin separation without magnetic field

Abstract

A nanodevice capable of separating spins of two electrons confined in a quantum dot formed in a gated semiconductor nanowire is proposed. Two electrons confined initially in a single quantum dot in the singlet state are transformed into the system of two electrons confined in two spatially separated quantum dots with opposite spins. In order to separate the electrons' spins we exploit transitions between the singlet and the triplet state, which are induced by resonantly oscillating Rashba spin-orbit coupling strength. The proposed device is all electrically controlled and the electron spin separation can be realized within tens of picoseconds. The results are supported by solving numerically the quasi-one-dimensional time-dependent Schroedinger equation for two electrons, where the electron-electron correlations are taken into account in the exact manner.

Oscillating spin-orbit interaction in two-dimensional superlattices: Sharp transmission resonances and time-dependent spin-polarized currents

“…6(b) represent the spin orientation (29) separately for the two, opposite input spin directions [see the first line of Eq. (33)], the incoherent sum of which constitutes the input density matrix (33). More precisely, the arrows visualize the spin direction in a local coordinate system; they point from (x,0,0) to (x + S x ,S y ,S z ).…”

All-electric single-electron spin-to-charge conversion

“…The solidstate qubit based on electron spin in electrostatic quantum dots is the easiest to implement and is one of a few promising candidates for quantum computing 24 . The Rashba type spin-orbit coupling (RSOI) 25,26 , which couples orbital and spin degrees of freedom, allows for efficient manipulation of the spin qubit [27][28][29][30][31][32][33][34][35][36] . Moreover, there are several possibilities to obtain a scalable quantum computation architecture consisting of multiple electron spins.…”

Electric-field-induced interferometric resonance of a one-dimensional spin-orbit-coupled electron

“…Being an intrinsic property of condensed-matter materials, spin-orbit coupling (SOC) mixes the orbital and spin degrees of particles, and opens the possibility of electric control of the electron spin via its orbit, apart from the well-known magnetic responses1234567891011121314151617. A notable example exploiting SOC in semiconductor nanostructures is called the electric-dipole spin resonance technique6789 (EDSR), in which a spin-orbit qubit is encoded into a SOC-hybridized spin doublet and an oscillating electric field is further applied to manipulate this qubit on its Bloch sphere.…”

“…For example, utilizing this technique, the single spin-orbit qubit operation has been achieved13 and the spin-orbit effective field can also be determined15, which reflects its potential application in quantum information processing and parameters measurement. In addition, the SOC-assisted spin control, such as the magnetic-free spin filtering1617 where the SOC serves as a necessary ingredient to spatially and electrically separate electrons with different spins, has also been achieved. In contrast to the conventional fully-magnetic control, the introduction of electric passage via SOC paves a much more experimentally feasible way to locally address electron spin, which may impact spintronics18.…”