Thursday's seminar

[CM]

CONDENSED MATTER AND STATISTICAL PHYSICS SECTION

   
SEMINAR on    Disorder and strong electron correlations




Thursday, 2 April-  11:00 a.m.




Seminar Room,  Leonardo Building - first floor






Robert S. WHITNEY    (Institut Laue-Langevin, Grenoble)




"Symmetry causes a huge conductance peak    in double quantum dots"


Abstract


We predict a huge interference effect contributing to the conductance 
through large ultra-clean quantum dots of chaotic shape. When a 
double-dot structure is made such that the dots are the mirror-image of 
each other, constructive interference can make a tunnel barrier located 
on the symmetry axis effectively transparent. We show (via theoretical 
analysis and numerical simulation) that this effect can be orders of 
magnitude larger than the well-known universal conductance fluctuations 
and weak-localization (both less than a conductance quantum). A small 
magnetic field destroys the effect, massively reducing the double-dot 
conductance; thus a magnetic field detector is obtained, with a similar 
sensitivity to a SQUID, but requiring no superconductors.

[Robert S. Whitney, P. Marconcini, M. Macucci, to appear in Phys. Rev. 
Lett. (2009) arXiv:0902.3099]