Phys. Rev. Lett. 100, 073601 (2008) [4 pages]Mach-Zehnder Interferometry at the Heisenberg Limit with Coherent and Squeezed-Vacuum LightReceived 31 May 2007; published 19 February 2008 We show that the phase sensitivity Δθ of a Mach-Zehnder interferometer illuminated by a coherent state in one input port and a squeezed-vacuum state in the other port is (i) independent of the true value of the phase shift and (ii) can reach the Heisenberg limit Δθ∼1/NT, where NT is the average number of input particles. We also demonstrate that the Cramer-Rao lower bound of phase sensitivity, Δθ∼ 1/√|α|2e2r+sinh2r, can be saturated for arbitrary values of the squeezing parameter r and the amplitude of the coherent mode α by using a Bayesian phase inference protocol. © 2008 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.100.073601
DOI:
10.1103/PhysRevLett.100.073601
PACS:
42.50.St, 42.50.Dv
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