Control of the transmission phase in an asymmetric four-terminal Aharonov-Bohm interferometer

TL;DR

This study demonstrates electrostatic control of the transmission phase in an asymmetric four-terminal Aharonov-Bohm interferometer, revealing how geometry and measurement circuitry influence phase coherence and dephasing mechanisms.

Contribution

It introduces a method to control the transmission phase electrostatically in an asymmetric four-terminal AB interferometer and analyzes the effects of geometry and circuitry on decoherence.

Findings

Phase control achieved via electrostatic tuning.

Geometry breaks phase rigidity, enabling continuous phase shifts.

Measurement circuitry affects dephasing mechanisms.

Abstract

Phase sensitivity and thermal dephasing in coherent electron transport in quasi one-dimensional (1D) waveguide rings of an asymmetric four-terminal geometry are studied by magnetotransport measurements. We demonstrate the electrostatic control of the phase in Aharonov-Bohm (AB) resistance oscillations and investigate the impact of the measurement circuitry on decoherence. Phase rigidity is broken due to the ring geometry: Orthogonal waveguide cross-junctions and 1D leads minimize reflections and resonances between leads allowing for a continuous electron transmission phase shift. The measurement circuitry influences dephasing: Thermal averaging dominates in the non-local measurement configuration while additional influence of potential fluctuations becomes relevant in the local configuration.