Heisenberg-limited metrology with a squeezed vacuum state, three-mode mixing, and information recycling

TL;DR

This paper demonstrates that using a three-mode-mixing model with information recycling in quantum-enhanced atom interferometry can achieve near-Heisenberg-limited phase sensitivities even at low quantum state transfer efficiencies.

Contribution

The study introduces a three-mode-mixing model with information recycling to improve phase sensitivity in atom interferometry beyond previous beamsplitter-based approaches.

Findings

Three-mode-mixing model outperforms beamsplitter model in phase sensitivity.

Near-Heisenberg-limited sensitivities achieved at low QST efficiencies.

Quantum Fisher information confirms near optimality of the scheme.

Abstract

We have previously shown that quantum-enhanced atom interferometry can be achieved by mapping the quantum state of squeezed optical vacuum to one of the atomic inputs via a beamsplitter-like process [Phys.~Rev.~A \textbf{90}, 063630 (2014)]. Here we ask the question: is a better phase sensitivity possible if the quantum state transfer (QST) is described by a three-mode-mixing model, rather than a beamsplitter? The answer is yes, but only if the portion of the optical state not transferred to the atoms is incorporated via information recycling. Surprisingly, our scheme gives a better sensitivity for lower QST efficiencies and with a sufficiently large degree of squeezing can attain near-Heisenberg-limited sensitivities for arbitrarily small QST efficiencies. Furthermore, we use the quantum Fisher information to demonstrate the near optimality of our scheme.