Aharonov-Bohm interferometry based on helical edge states1) (Mini-review)
R. A. Niyazov+* 2), D. N. Aristov+*, V. Yu. Kachorovskii×
+Department of Physics, St. Petersburg State University, 198504 St. Petersburg, Russia
*National Research Centre "Kurchatov Institute", Petersburg Nuclear Physics Institute, 188300 Gatchina, Russia
×Ioffe Institute, 194021 St. Petersburg, Russia
We review recent studies of the spin-dependent tunneling transport via Aharonov-Bohm
interferometer (ABI) formed by helical edge states.
We focus on the experimentally relevant case of relatively high
temperature, T, as compared to level spacing, Δ. The tunneling conductance
of helical ABI is structureless in ballistic case but shows sharp
periodic antiresonances as a function of magnetic flux - with the
period hc/2e - in presence of magnetic impurities.
The incoming unpolarized electron beam acquires finite polarization
after transmission through the helical ABI provided that the edges
contain at least one magnetic impurity. The finite polarization
appears even in the fully classical regime and is therefore robust to
dephasing. There is also a quantum
contribution to the polarization, which
shows sharp identical resonances as a function of magnetic flux
with the same period as conductance. This polarization survives at
relatively high temperature. The interferometer can be described in
terms of ensemble of flux-tunable qubits
giving equal contributions to conductance and spin polarization. Hence,
with increasing the temperature number of active qubits participating in
the charge and spin transport increases.
These features of tunneling helical ABI open a wide avenue for
applications in the area of quantum computing.