Dual epitaxial telecom spin-photon interfaces with long-lived coherence.

Area of Science:

• Quantum Information Science
• Materials Science
• Optoelectronics

Background:

• Solid-state spin qubits are promising for quantum networks due to their scalability and coherence.
• Trivalent erbium (Er3+) ions are attractive for telecom-band quantum applications.
• Existing rare-earth qubit architectures struggle with simultaneous long optical and spin coherence.

Purpose of the Study:

• To demonstrate dual spin-photon interfaces using Er3+ qubits in different lattice sites.
• To achieve simultaneous long optical and spin coherence for efficient quantum networking.
• To enable scalable quantum light-matter interfaces for telecommunication networks.

Main Methods:

• Fabrication of an epitaxial thin-film platform with high matrix crystallinity.
• Controlled placement of Er3+ dopants near surfaces and exploitation of host lattice symmetry.
• Characterization of optical linewidth and spin coherence times, including single-shot readout and microwave control.

Main Results:

• Simultaneous achievement of kilohertz-level optical linewidth and >10 ms spin coherence times for Er3+ qubits.
• Demonstration of qubits in two distinct lattice symmetry sites.
• Realization of single-shot readout and microwave coherent control in a fiber-integrated package.

Conclusions:

• High-quality rare-earth qubits assembled via bottom-up methods show significant potential for quantum networks.
• The developed platform enables scalable quantum light-matter interfaces tailored for telecommunication wavelengths.
• This work paves the way for efficient long-distance quantum communication using solid-state spin qubits.