Generating nonlinearities from conditional linear operations, squeezing and measurement for quantum computation and super-Heisenberg sensing

TL;DR

This paper introduces a novel protocol to generate large optical nonlinearities using conditional linear operations, measurement, and correction, enabling creation of cat-states and super-Heisenberg sensing with potential atomic ensemble implementation.

Contribution

The paper presents a new method to produce large optical nonlinearities through conditional linear operations and measurements, advancing quantum computation and sensing capabilities.

Findings

Protocol can generate high-quality optical Schrödinger cat states

Enables sensing with super-Heisenberg scaling

Potential implementation with atomic ensembles via Faraday effect

Abstract

Large optical nonlinearities can have numerous applications, ranging from the generation of cat-states for optical quantum computation, through to quantum sensing where the sensitivity exceeds Heisenberg scaling in the resources. However, the generation of ultra-large optical nonlinearities has proved immensely challenging experimentally. We describe a novel protocol where one can effectively generate large optical nonlinearities via the conditional application of a linear operation on an optical mode by an ancilla mode, followed by a measurement of the ancilla and corrective operation on the probe mode. Our protocol can generate high quality optical Schr{\"{o}}dinger cat states useful for optical quantum computing and can be used to perform sensing of an unknown rotation or displacement in phase space, with super-Heisenberg scaling in the resources. We finally describe a potential experimental implementation using atomic ensembles interacting with optical modes via the Faraday effect.