Hyperentanglement of divalent neutral atoms by Rydberg blockade

TL;DR

This paper demonstrates the creation of hyperentanglement in individual neutral atoms using Rydberg blockade, enabling simultaneous entanglement in electronic and nuclear qubits for advanced quantum applications.

Contribution

It introduces a method to generate hyperentanglement in neutral atoms by leveraging Rydberg blockade to entangle both electronic and nuclear qubits simultaneously.

Findings

Controlled-Z operation achieved in electronic qubits.

Simultaneous entanglement of nuclear qubits demonstrated.

Potential for new quantum technologies using neutral atoms.

Abstract

Hyperentanglement~(HE), the simultaneous entanglement between two particles in more than one degrees of freedom, is relevant to both fundamental physics and quantum technology. Previous study on HE has been focusing on photons. Here, we study HE in individual neutral atoms. In most alkaline-earth-like atoms with two valence electrons and a nonzero nuclear spin, there are two stable electronic states, the ground state and the long-lived clock state, which can define an electronic qubit. Meanwhile, their nuclear spin states can define a nuclear qubit. By the Rydberg blockade effect, we show that the controlled-Z~(C$_{\text{Z}}$) operation can be generated in the electronic qubits of two nearby atoms, and simultaneously in their nuclear qubits as well, leading to a C$_{\text{Z}}\otimes$C$_{\text{Z}}$ operation which is capable to induce HE. The possibility to induce HE in individual neutral atoms offers new opportunities to study quantum science and technology based on neutral atoms.