Hi all,
Our guest Normand Beaudry will give a talk this Thursday at 4pm in HIT K51.
Hope you can make it.
Roger
--- "Squashing Models for Optical Measurements in Quantum Communication"
Photodetection devices are naturally described by the infinite-dimensional Fock space of one or several modes. However, for many quantum communication applications, it is required that measurements are performed on single photons, or qubits. I will outline a model, which describes a full measurement on many modes as a composition of a mapping (squashing) of the signal into a small-dimensional Hilbert space followed by a specified target measurement. Using this model, we can show that security proofs of qubit quantum key distribution protocols can be generalised to include the protocol's full optical implementation. For example, the BB84 protocol's polarization measurement has a squashing model, while surprisingly the corresponding six-state protocol measurement does not. In addition, I will also show how any full measurement can have a squashing model with respect to any target measurement, provided a modification of the full measurement. Time permitting, I will discuss the implications of the squashing model in the context of entanglement verification.