HUGO CABLE
(National University of Singapore)

QUANTUM KRISPY KREME SEMINAR:

THE POWER OF HIGH-DIMENSIONAL SINGLET STATES
FOR ULTRA-PRECISE MEASUREMENTS

ABSTRACT: Heisenberg limit of N^{-1}.  However, achieving this is hard because of
practical limits to scalability and decoherence processes. I will
explain this bigger picture,  and also my current proposal (in
collaboration with Dr Gabriel Durkin) for using two spin-j systems
combined in an overall spin-zero singlet as a quantum probe.  Singlet
states have properties which suggest their usefulness: scalable
generation using stimulated parametric down-conversion, rotational
symmetry and loss tolerance. We have found a surprisingly positive
result - that the best precision possible for our protocol using singlet
states is never worse than the best classical measuring device when
photon losses arising in transmission and detection are fully accounted for.