QDev Seminar: Tom Stace

Cross-Kerr non-linearities for quantum non-demolition measurement of microwave photons

Various proposals exist that exploit cross-Kerr non-linearities between electromagnetic fields, for quantum non-demolition (QND) measurements, and other related protocols.  Typically, these proposals assume the existence of such non-linearities, based on a presumption that the internal dynamics of the medium can be eliminated from the problem.  I will discuss some recent work in which we explicitly include the medium, with rather surprising implications for QND counting of microwave photons.