IQIS Quantum Institute Seminar: Dominic Berry

  • Date: 04/25/2012
  • Time: 15:00
Dominic Berry

University of Calgary


Universality of the Heisenberg limit for estimates of random phase shifts




The Heisenberg limit traditionally provides a lower bound on
the phase uncertainty scaling as 1/N, where N is the mean number of
photons in the probe. However, this limit has a number of loopholes
which potentially might be exploited, to achieve measurements with even
greater accuracy. We have closed these loopholes by proving a completely
rigorous form of the Heisenberg limit for the average error over all
phase shifts. Our result gives the first completely general,
constraint-free and non-asymptotic statement of the Heisenberg limit. It
holds for all phase estimation schemes, including multiple passes,
nonlinear phase shifts, multimode probes, and arbitrary measurements.

Other Information: 

Location: SB 148


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