Phys Rev Lett. 2013 Jun 21;110(25):250404. doi: 10.1103/PhysRevLett.110.250404. Epub 2013 Jun 21.

Nonsymmetrized correlations in quantum noninvasive measurements.

Physical review letters

Adam Bednorz, Christoph Bruder, Bertrand Reulet, Wolfgang Belzig

PMID: 23829718 DOI: 10.1103/PhysRevLett.110.250404

Abstract

A long-standing problem in quantum mesoscopic physics is which operator order corresponds to noise expressions like , where I(ω) is the measured current at frequency ω. Symmetrized order describes a classical measurement while nonsymmetrized order corresponds to a quantum detector, e.g., one sensitive to either emission or absorption of photons. We show that both order schemes can be embedded in quantum weak-measurement theory taking into account measurements with memory, characterized by a memory function which is independent of a particular experimental detection scheme. We discuss the resulting quasiprobabilities for different detector temperatures and how their negativity can be tested on the level of second-order correlation functions already. Experimentally, this negativity can be related to the squeezing of the many-body state of the transported electrons in an ac-driven tunnel junction.

Publication Types

• Journal Article