Measurement of physical quantities is central to all sciences, and improvements in precision have lead to not only more detailed knowledge, but also new fundamental understanding. A crucial question is with what precision such measurements can be made. The laws of quantum theory put lower bounds on the precision that can be achieved in an experiment. It is known that in some cases quantum states of light can be used to increase the precision of phase measurements. The so-called NOON states of light, in which two modes (a and b) of the electromagnetic field are in a superposition of having N photons in mode a and 0 in mode b and 0 photons in mode a and N photons in mode b, are one example where quantum states improve precision. However, when one considers cases in which photon loss occurs, such quantum-enhanced schemes are not always the optimal approach. I present recent results demonstrating heralded NOON states, which represents a first step towards facing the reality of photon loss.


Seminar, November 20, 2008, 17:00. Seminar Room

Hosted by Prof. Morgan Mitchell