Long-lived mesoscopic entanglement outside the Lamb-Dicke regime

Abstract

We create entangled states of the spin and motion of a single ${}^{40}$Ca${}^{+}$ ion in a linear ion trap. The motional part consists of coherent states of large separation and long coherence time. The states are created by driving the motion using counterpropagating laser beams. We theoretically study and experimentally observe the behaviour outside the Lamb-Dicke regime, where the trajectory in phase space is modified and the coherent states become squeezed. We directly observe the modification of the return time of the trajectory, and infer the squeezing. The mesoscopic entanglement is observed up to $\Delta \alpha =5.1$ with coherence time 170 microseconds and mean phonon excitation $\nbar = 16$.

5 pages, 3 figures. Revised version after editor comments

References in corpus (1)

• Scalable multi-particle entanglement of trapped ions

Cited by in corpus (4)

• Deterministic entanglement and tomography of ion spin qubits
• Probing the quantum coherence of a nanomechanical resonator using a superconducting qubit: I. Echo scheme
• Ramsey interferometry with a spin embedded in a Coulomb chain
• Quantum interference structures in trapped ion dynamics beyond the Lamb-Dicke and rotating wave approximations