Anomalous magnetotransport through reflection-symmetric artificial molecules

TL;DR

This paper investigates magnetotransport oscillations in reflection-symmetric triple quantum-dot molecules, revealing that odd harmonics can dominate and that flux-independence occurs under certain symmetries, aligning with recent experimental observations.

Contribution

It demonstrates that reflection symmetry in triple quantum dots leads to flux-independent current and dominant odd harmonics, challenging previous dark-state localization predictions.

Findings

Odd harmonics can dominate over even harmonics in symmetric systems.

Flux-independent current occurs in reflection-symmetric Aharonov-Bohm networks.

Effects are observable despite typical dephasing sources.

Abstract

We calculate magnetotransport oscillations in current through a triple-quantum-dot molecule, accounting for higher harmonics (having flux period h/ne, with n an integer). For a reflection-symmetric triple quantum dot, we find that harmonics with n odd can dominate over those with n even. This is opposite to the behavior theoretically predicted due to `dark-state' localization, but has been observed in recent experiments [L. Gaudreau et al., Phys. Rev. B, 80, 075415 (2009)], albeit in a triple-dot that may not exhibit reflection symmetry. This feature arises from a more general result: In the weak-coupling limit, we find that the current is flux-independent for an arbitrary reflection-symmetric Aharonov-Bohm network. We further show that these effects are observable in nanoscale systems even in the presence of typical dephasing sources.