Quantum limited measurements of atomic scattering properties

TL;DR

This paper introduces a quantum measurement technique that leverages entanglement and spin squeezing to achieve ultra-precise atomic interaction measurements, surpassing classical limits even with decoherence.

Contribution

It presents a novel method for precision atomic scattering measurements using spin squeezing, reducing fundamental measurement limits and demonstrating robustness against decoherence.

Findings

Achieves measurement precision scaling as N^(-2) due to spin squeezing.

Entangled states outperform non-entangled states under decoherence.

Proposes two experimental implementations with Bose-Einstein condensates and optical lattices.

Abstract

We propose a method to perform precision measurements of the interaction parameters in systems of N ultra-cold spin 1/2 atoms. The spectroscopy is realized by first creating a coherent spin superposition of the two relevant internal states of each atom and then letting the atoms evolve under a squeezing Hamiltonian. The non-linear nature of the Hamiltonian decreases the fundamental limit imposed by the Heisenberg uncertainty principle to N^(-2), a factor of N smaller than the fundamental limit achievable with non-interacting atoms. We study the effect of decoherence and show that even with decoherence, entangled states can outperform the signal to noise limit of non-entangled states. We present two possible experimental implementations of the method using Bose-Einstein spinor condensates and fermionic atoms loaded in optical lattices and discuss their advantages and disadvantages.