1202.3591 (P-A. Huynh et al.)

Quantum coherence engineering in the integer quantum Hall regime    [PDF]

P-A. Huynh, F. Portier, H. le Sueur, G. Faini, U. Gennser, D. Mailly, F. Pierre, W. Wegscheider, P. Roche

We present an experiment where the quantum coherence in the edge states of
the integer quantum Hall regime is tuned with a decoupling gate. The coherence
length is determined by measuring the visibility of quantum interferences in a
Mach-Zehnder interferometer as a function of temperature, in the quantum Hall
regime at filling factor two. The temperature dependence of the coherence
length can be varied by a factor of two. The strengthening of the phase
coherence at finite temperature is shown to arise from a reduction of the
coupling between co-propagating edge states. This opens the way for a strong
improvement of the phase coherence of Quantum Hall systems. The decoupling gate
also allows us to investigate how inter-edge state coupling influence the
quantum interferences' dependence on the injection bias. We find that the
finite bias visibility can be decomposed into two contributions: a Gaussian
envelop which is surprisingly insensitive to the coupling, and a beating
component which, on the contrary, is strongly affected by the coupling.

View original: http://arxiv.org/abs/1202.3591