Time-reversal Interferometry Using Cat States with Scalable Entangling Resources

TL;DR

This paper introduces a scalable method for generating Schrödinger-cat states with enhanced phase sensitivity, leveraging a time-reversal protocol and entangling resources that improve quantum metrology performance.

Contribution

A novel, efficient protocol for creating cat states with scalable entangling resources that maintains Heisenberg limit scaling under realistic conditions.

Findings

Shearing strength decreases as 1/√N with more atoms.

Generated states achieve optimal quantum Fisher information.

Protocol remains effective under realistic loss conditions.

Abstract

We propose a novel method for generating Schr\"odinger-cat states -- defined as equal superpositions of arbitrary coherent states -- using a concise sequence of rapid twist-and-turn pulses. We demonstrate that the required shearing strength for the protocol, which scales linearly with time, decreases with increasing number of atoms ($N$) in proportion to $1/\sqrt{N}$. The resulting states exhibit optimal quantum Fisher information, making them ideal for surpassing the classical limit of phase sensitivity in quantum metrology applications. Notably, our protocol is compatible with a time-reversal strategy for quantum metrology, ensuring its practical viability. Furthermore, we demonstrate that the Heisenberg limit scaling remains intact even when reducing the twisting employed in tandem with the number of atoms, thereby mitigating realistic losses such as photon scattering.