ALP Seminar: Quantum measurement through parametric amplification

Quantum states of light are central to photonic quantum technologies, and their measurement is therefore very important. But quantum states are famous for being fragile. This is true for squeezed states of light, and even more true for non-Gaussian states – which are really weird from a classical viewpoint. Fortunately, a nonlinear-optical device known as the optical parametric amplifier comes to rescue when measurement over a fragile quantum state is needed. It protects the measurement against optical losses and imperfect detection, enables addressing several modes at the same time, and can substitute homodyne detection with direct detection. In my talk I will show how, by applying parametric amplification, one can perform neat quantum measurements despite imperfect detection, characterize a multimode quantum state, and fully reconstruct the quantum state of a single mode.