Effect Of Wire Length On Quantum Coherence In Ingaas Wires

Quantum phase coherence lengths were experimentally measured in nanolithographic wires to investigate the effects of wire length on quantum decoherence, which can be limited by mechanisms such as coupling to an external classical environment. The work demonstrates that device geometry and coupling to the environment have to be taken into account in quantum coherence, of relevance in quantum technologies using electronic nanostructures. The low-temperature measurements of the quantum phase coherence lengths use quantum transport, specifically antilocalization, on wires fabricated from an InGaAs/InAlAs heterostructure. It is observed that longer wire lengths result in longer quantum phase coherence lengths, tending to an asymptotic value in long wires. The results are understood from the observation that longer wires average out the quantum decoherence introduced at the end sections by coupling to the external environment. The experimental results are quantitatively compatible with a model expressing reduced backscattered amplitude due to quantum interference at the wire ends.