Weak value amplification of atomic cat states

TL;DR

This paper demonstrates how weak value amplification enhances the detection of quantum interference and phase shifts in atomic cat states, enabling discrimination of closely lying states with improved sensitivity.

Contribution

It introduces a method using weak value amplification to observe and amplify quantum interference effects in atomic cat states, improving state discrimination.

Findings

Amplification factor of 15 achieved with 10 atoms.

Atomic cat states become more nonclassical with certain post-selections.

Method enables discrimination of close quantum states on the Bloch sphere.

Abstract

We show the utility of the weak value amplification to observe the quantum interference between two close lying atomic coherent states in a post-selected atomic cat state, produced in a system of $N$ identical two-level atoms weakly interacting with a single photon field. Through the observation of the negative parts of the Wigner distribution of the post-selected atomic cat state, we find that the post-selected atomic cat state becomes more nonclassical when the post-selected polarization state of the single photon field tends toward becoming orthogonal to its pre-selected state. We show that the small phase shift in the post-selected atomic cat state can be amplified via measuring the peak shift of its phase distribution when the post-selected state of the single photon field is nearly orthogonal to its pre-selected state. We find that the amplification factor of 15 [5] can be obtained for a sample of 10 [100] atoms. This effectively provides us with a method to discriminate two close lying states on the Bloch sphere. We discuss possible experimental implementation of the scheme, and conclude with a discussion of the Fisher information.