Approaching the Heisenberg limit without single-particle detection

TL;DR

This paper introduces a method for quantum phase estimation that approaches the Heisenberg limit without single-particle detection, using interaction-based readout to amplify signals in entangled states, even amid noise and dissipation.

Contribution

It demonstrates that one-axis twisting interactions can be used to amplify signals for phase estimation, enabling near-Heisenberg-limited precision without single-particle resolution.

Findings

Achieves Heisenberg scaling in phase sensitivity with oversqueezed states.

Maintains high precision despite large detection noise.

Applicable in dissipative systems like optical cavities and Rydberg dressing.

Abstract

We propose an approach to quantum phase estimation that can attain precision near the Heisenberg limit without requiring single-particle-resolved state detection. We show that the "one-axis twisting" interaction, well known for generating spin squeezing in atomic ensembles, can also amplify the output signal of an entanglement-enhanced interferometer to facilitate readout. Applying this interaction-based readout to oversqueezed, non-Gaussian states yields a Heisenberg scaling in phase sensitivity, which persists in the presence of detection noise as large as the quantum projection noise of an unentangled ensemble. Even in dissipative implementations -- e.g., employing light-mediated interactions in an optical cavity or Rydberg dressing -- the method significantly relaxes the detection resolution required for spectroscopy beyond the standard quantum limit.