Mach-Zehnder Interferometry at the Heisenberg Limit with coherent and squeezed-vacuum light

Abstract

We show that the phase sensitivity $\Delta \theta$ of a Mach-Zehnder interferometer fed by a coherent state in one input port and squeezed-vacuum in the other one is i) independent from the true value of the phase shift and ii) can reach the Heisenberg limit $\Delta \theta \sim 1/N_T$, where $N_T$ is the average number of particles of the input states. We also show that the Cramer-Rao lower bound, $\Delta \theta \propto 1/\sqrt{|\alpha {|}^2{e}^{2r}+{\sinh }^{2}r}$, can be saturated for arbitrary values of the squeezing parameter $r$ and the amplitude of the coherent mode $|\alpha |$ by a Bayesian phase inference protocol.

4 pages, 4 figures

References in corpus (5)

• Observation of -9 dB quadrature squeezing with improvement of phase stability in homodyne measurement
• Coherent control of vacuum squeezing in the Gravitational-Wave Detection Band
• Phase detection at the quantum limit with multi-photon Mach-Zehnder interferometry
• Quantum entanglement of a large number of photons
• Demonstration of a squeezed light enhanced power- and signal-recycled Michelson interferometer

Cited by in corpus (3)

• All path-symmetric pure states achieve their maximal phase sensitivity in conventional two-path interferometry
• Optimized Double-well quantum interferometry with Gaussian squeezed-states
• Quantum enhancement of N-photon phase sensitivity by interferometric addition of down-converted photon pairs to weak coherent light