Experimental Preparation of High NOON States for Phonons

TL;DR

This paper presents a deterministic method for creating high NOON states of phonons, successfully generating states up to N=9, and demonstrates their quantum advantages in phase sensitivity, with broad applicability.

Contribution

The authors develop a universal, deterministic approach to generate high NOON states for phonons and experimentally realize states up to N=9, surpassing previous limitations.

Findings

NOON states up to N=9 phonons created with high fidelity.

Measured quantum Fisher information shows Heisenberg scaling.

State fidelity exceeds classical limits, confirming quantum advantage.

Abstract

Multi-party entangled states have important applications in quantum metrology and quantum computation. Experimental preparation of large entangled state, in particular, the NOON states, however, remains challenging as the particle number $N$ increases. Here we develop a deterministic method to generate arbitrarily high NOON states for phonons and experimentally create the states up to $N=9$ phonons in two radial modes of a single trapped \Yb ion. We demonstrate that the fidelity of the NOON states are significantly above the classical limit by measuring the interference contrast and the population through the projective phonon measurement of two motional modes. We also measure the quantum Fisher information of the generated NOON state and observe the Heisenberg scaling in the lower bounds of the phase sensitivity as the $N$ increases. Our scheme is generic and applicable to other photonic or phononic systems.