Anomalous maqnetotransport through reflection-symmetric artificial molecules

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) (http://dx.doi.org/10.1103/PhysRevB.80.075415)]. 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.