Mach-Zehnder Interferometry at the Heisenberg Limit with Coherent and Squeezed-Vacuum Light

2007/05/31 by Luca Pezzè, L. Pezze', Augusto Smerzi +1 · 2 citations
Computer Science · Physics and Astronomy · #Neural Networks and Reservoir Computing #Quantum Information and Cryptography #Quantum optics and atomic interactions #cond-mat.other #quant-ph

paper · pdf · doi:10.1103/physrevlett.100.073601

4 pages, 4 figures

arxiv created 2007/05/31 · openalex publication_date 2008/02/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We show that the phase sensitivity \ensuremathΔ\ensuremathθ 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 \ensuremathΔ\ensuremathθ\ensuremath∼1/N_T, where N_T is the average number of input particles. We also demonstrate that the Cramer-Rao lower bound of phase sensitivity, \ensuremathΔ\ensuremathθ\ensuremath∼\phantom\rule0ex0ex1/√|\ensuremathα|²e^2r+sinh²r, can be saturated for arbitrary values of the squeezing parameter r and the amplitude of the coherent mode \ensuremathα by using a Bayesian phase inference protocol.

Citations

• Quantum-enhanced measurements: beating the standard quantum limit
• Quantum Entanglement of a Large Number of Photons
• Adaptive Homodyne Measurement of Optical Phase

Cited by

• All path-symmetric pure states achieve their maximal phase sensitivity in conventional two-path interferometry
• Quantum information with conserved quantities