Robust helical edge transport in quantum spin Hall quantum wells
Rafal Skolasinski (TU Delft - Quantum Computing Division, Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre)
D. Pikulin (Microsoft Quantum Lab Delft, TU Delft - QN/Theoretical Physics)
Jason Alicea (California Institute of Technology)
Michael Wimmer (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - QRD/Wimmer Group)
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Abstract
We show that edge-state transport in semiconductor-based quantum spin Hall systems is unexpectedly robust to magnetic fields. The origin for this robustness lies in an intrinsic suppression of the edge-state g-factor and the fact that the edge-state Dirac point is typically hidden in the valence band. A detailed k·p band-structure analysis reveals that both InAs/GaSb and HgTe/CdTe quantum wells exhibit such buried Dirac points for a wide range of well thicknesses. By simulating transport in a disordered system described within an effective model, we demonstrate that edge-state transport remains nearly quantized up to large magnetic fields, consistent with recent experiments.
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