Quantum rings as electron spin beam splitters

Abstract

Quantum interference and spin-orbit interaction in a one-dimensional mesoscopic semiconductor ring with one input and two output leads can act as a spin beam splitter. Different polarization can be achieved in the two output channels from an originally totally unpolarized incoming spin state, very much like in a Stern-Gerlach apparatus. We determine the relevant parameters such that the device has unit efficiency.Comment: 4 pages, 3 figures; minor change

Spin filtering in all-electrical three-terminal interferometers

“…This symmetric case was explored in a ring interferometer in Ref. 23. However, the conditions (26) can be fulfilled also when the two arms of the interferometer are not precisely identical, since the condition y b = y c does not require the arms bd and cd to be identical.…”

“…[13][14][15][16][17] Alternatively, one may increase the number of terminals connected to the device and thus generate a finite spin polarization without exploiting ferromagnetic electrodes and without applying magnetic fields. Allelectrical single-loop spin filters based on three-terminal devices have been studied before; [20][21][22][23][24] in particular, Földi et al 23 demonstrated that a symmetric-ring interferometer attached to one source and two drain terminals can act as a spin beam-splitter, which polarizes the electrons in the output leads along tunable directions. In the first part of this paper we extend this result to a more realistic setup.…”

Filtering and analyzing mobile qubit information via Rashba–Dresselhaus–Aharonov–Bohm interferometers

“…Some papers also suggested to connect the loop to three leads, as in a Stern-Gerlach experiment. 52,53 However, the calculated criteria for filtering in these papers were usually energy-dependent, and there was no systematic discussion of these criteria and of the polarization of the transmitted spins. An alternative geometry replaces the circular loop by a diamond-shaped square, with a SOI on its four edges (which determine ω) and with a penetrating AB flux, see Fig.…”

Stable switch action based on quantum interference effect

“…Earlier works have proposed junction S matrix for solving the scattering problem of a ring [10][11][12][13][14][15][16][17]23,24 where the following conditions are satisfied at the junction: (a) conservation of current, (b) continuity of wave function and (c) unitarity of S matrix. However, earlier models do not account for channel mixing and also do not allow us to include evanescent modes.…”

“…These devices can be exploited if we achieve the technology that can reduce or control the phase fluctuations to a small fraction of 2π 9 . A lot of work has been done in one dimensional quantum rings [9][10][11][12][13][14][15][16][17][18] . However, the experimental rings are always in two dimension or in three dimension.…”