Orbital-angular-momentum-enhanced estimation of sub-Heisenberg-limited angular displacement with two-mode squeezed vacuum and parity detection

TL;DR

This paper presents an enhanced angular displacement estimation method using orbital angular momentum and two-mode squeezed vacuum, achieving sub-Heisenberg sensitivity and robustness against realistic noise factors.

Contribution

It introduces a scheme that improves sensitivity and robustness in angular displacement estimation by leveraging orbital angular momentum without increasing photon number.

Findings

Achieves sub-Heisenberg-limited sensitivity in ideal conditions.

Raising orbital angular momentum quantum number offsets effects of noise.

System robustness and practicality are improved without increasing mean photon number.

Abstract

We report on an orbital-angular-momentum-enhanced scheme for angular displacement estimation based on two-mode squeezed vacuum and parity detection. The sub-Heisenberg-limited sensitivity for angular displacement estimation is obtained in an ideal situation. Several realistic factors are also considered, including photon loss, dark counts, response-time delay, and thermal photon noise. Our results indicate that the effects of the realistic factors on the sensitivity can be offset by raising orbital angular momentum quantum number $\ell$. This reflects that the robustness and the practicability of the system can be improved via raising $\ell$ without changing mean photon number $N$.