Green, FrederickThakur, Jagdish SDas, Mukunda P2009-10-272010-12-202009-10-272010-12-20Physical Review Letters 92.15 (2004): 156804/1-40031-90071079-7114http://hdl.handle.net/10440/973http://digitalcollections.anu.edu.au/handle/10440/973Reznikov et al. [Phys. Rev. Lett. 75, 3340 (1995)] have presented definitive observations of nonequilibrium noise in a quantum point contact. Especially puzzling is the “anomalous” peak structure of the excess noise measured at constant current; to date it remains unexplained. We show that their experiment directly reveals the deep link between conservation principles in the electron gas and its low-dimensional, mesoscopic behavior. The keys to that connection are gauge invariance and the compressibility sum rule. These are central not only to the experiment of Reznikov et al., but to the very nature of all mesoscopic transport.4 pagesThe author has the right to deposit the final version or the APS-prepared version on the ANU institutional repository as long the author was employed by the ANU when the paper was published and the repository is for the ANU Canberra campus only, not joint with other universities or other entities. (Email from APS, Publications Marketing Coordinator, 30/7/09). Copyright statement: © 2004 The American Physical SocietyKeywords: Carrier concentration; Compressibility; Electric conductivity; Electric current measurement; Electron devices; Electron gas; Fermi level; Mathematical models; Phonons; Chemical potential; Dynamical electron relaxation; Hot-electron noise; Quantum point co2004-04-1610.1103/PhysRevLett.92.1568042015-12-11