DQC Seminar Series: Rare-earth Ion Qubits: A Path to Scalable Quantum Networking

Presenter: Andrei Ruskuc, Postdoc, Harvard University

Quantum networks unlock a broad range of applications in quantum information science, ranging from secure communication to distributed sensing and computation. My talk will explore an experimental platform based on rare-earth ion qubits: emitters inherently shielded from environmental perturbations, creating near-pristine atomic systems in the solid-state. I will present three key advancements:

1. A novel solid-state platform where 171Yb3+ ions in YVO4 are coupled to nanophotonic cavities and utilized as highly coherent optically addressed qubits.
2. Deterministic memory registers based on nuclear spin ensembles, capable of storing and retrieving quantum states on demand
3. Multiplexed entanglement links which utilize multiple rare-earth ions to eliminate quantum communication rate bottlenecks between remote nodes.

I will conclude with a vision on scaling these rare-earth ion systems for a range of quantum communication applications such as quantum repeaters and cluster-state generation.
Time-permitting, I will also discuss ongoing postdoctoral research on quantum networking with 87Rb atom arrays. The goal is to use high-finesse Fabry-Perot cavities to interface with telecommunication-band optical transitions, enabling seamless integration with silicon photonics and entanglement over metropolitan distances.
---
Andrei Ruskuc is a postdoctoral fellow in the Lukin group at Harvard, researching atomic platforms for quantum networking. He completed his PhD in 2023 at Caltech under Andrei Faraon, focusing on rare-earth ion-based quantum networking technologies. He holds bachelor's and master's degrees from the University of Cambridge (2017). His expertise spans quantum networking with both solid-state and neutral atom platforms.