Precision phase measurement in Mach-Zehnder interferometer with three-photon by using a weak coherent and a squeezed vacuum state

TL;DR

This paper investigates phase measurement in a Mach-Zehnder interferometer using a combination of weak coherent and squeezed vacuum states, demonstrating that optimal ratios can achieve Heisenberg-limited sensitivity.

Contribution

It introduces a method to quantify phase sensitivity in MZI with combined quantum states, reaching the Heisenberg limit at optimal ratios.

Findings

Phase sensitivity reaches the Heisenberg limit at optimal ratios.

The measured three-photon coincidence varies with the ratio of coherent to squeezed vacuum.

The approach provides a new way to quantify phase sensitivity in quantum metrology.

Abstract

We quantitatively investigate phase measurement in a Mach-Zehnder interferometer (MZI), which is injected with a weak coherent and a squeezed vacuum generated from a spontaneous parametric down-conversion. The measured three-photon coincidence in this system is quantified as a function of a ratio between the amplitude of the coherent state and the squeezed parameter of squeezed vacuum when the photon number is detected at one output of MZI. It shows that the phase sensitivity reaches the Heisenberg limit when an optimal ratio is chosen. This may introduce one approach to quantify phase sensitivity in precision phase measurement.