Quantum entanglement at ambient conditions in a macroscopic solid-state spin ensemble.

Area of Science:

• Quantum Information Science
• Condensed Matter Physics
• Materials Science

Background:

• Entanglement is crucial for quantum computing, communication, and sensing.
• Macroscopic spin ensembles offer long coherence and strong signals but typically require extreme conditions.
• Previous methods for creating entangled spin states demanded high magnetic fields, cryogenic temperatures, or photochemical reactions.

Purpose of the Study:

• To demonstrate the creation of entangled states in solid-state spin ensembles under ambient conditions.
• To explore the potential of hybrid electron-nuclear spin registers for quantum applications.

Main Methods:

• Utilized hybrid registers of electron-nuclear spin pairs localized at color-center defects in a silicon carbide (SiC) wafer.
• Optically initialized 10^3 identical registers within a 40-μm^3 volume.
• Deterministically prepared registers into maximally entangled Bell states.

Main Results:

• Achieved deterministic preparation of entangled Bell states with a fidelity of 0.88 ± 0.07.
• Developed a register-specific quantum-state tomography protocol to verify entanglement.
• Successfully created entanglement in a macroscopic solid-state spin ensemble at room temperature.

Conclusions:

• Realizing entanglement in solid-state spin ensembles at ambient conditions is a significant advancement.
• This work moves practical quantum technology closer to reality by overcoming previous environmental limitations.
• Hybrid spin registers in SiC offer a promising platform for scalable quantum information processing.