Negativity of the excess noise in a quantum wire capacitively coupled to a gate
Abstract
The electrical current noise of a quantum wire is expected to increase with increasing applied voltage. We show that this intuition can be wrong. Specifically, we consider a singlechannel quantum wire with impurities and with a capacitive coupling to nearby metallic gates and find that its excess noise, defined as the change in the noise caused by the finite voltage, can be negative at zero temperature. This feature is present both for large (c≫c_{q}) and small (c≪c_{q}) capacitive coupling, where c is the geometrical and c_{q} the quantum capacitance of the wire. In particular, for c≫c_{q} , negativity of the excess noise can occur at finite frequency when the transmission coefficients are energy dependent—i.e., in the presence of FabryPérot resonances or band curvature. In the opposite regime c≲c_{q} , a nontrivial voltage dependence of the noise arises even for energyindependent transmission coefficients: at zero frequency the noise decreases with voltage as a power law when c<c_{q}/3 , while, at finite frequency, regions of negative excess noise are present due to Andreevtype resonances.
 Publication:

Physical Review B
 Pub Date:
 January 2007
 DOI:
 10.1103/PhysRevB.75.045332
 arXiv:
 arXiv:condmat/0609227
 Bibcode:
 2007PhRvB..75d5332D
 Keywords:

 73.23.b;
 72.70.+m;
 72.10.d;
 Electronic transport in mesoscopic systems;
 Noise processes and phenomena;
 Theory of electronic transport;
 scattering mechanisms;
 Condensed Matter  Strongly Correlated Electrons;
 Condensed Matter  Mesoscopic Systems and Quantum Hall Effect
 EPrint:
 11 pages, 5 figures. Revised version, references and technical details added, typos corrected