Ultralong Room-Temperature Qubit Lifetimes of Covalent Organic Frameworks

TL;DR

This paper demonstrates that covalent organic frameworks can host stable organic radical qubits with ultralong relaxation times at room temperature, advancing quantum information technology and sensing applications.

Contribution

It introduces COFs as programmable matrices for radical qubits, achieving ultralong T1 times at room temperature, outperforming many molecular qubits and rivaling inorganic defects.

Findings

Achieved T1 > 300 μs at 298 K in COFs

Suppressed spin relaxation via rigid structures and spin distribution

Enabled room-temperature nuclear spin detection

Abstract

Molecular electron spin qubits offer atomic-level tunability and room-temperature quantum coherence. Their integration into engineered solid-state matrices can enhance performance towards ambient quantum information technologies. Herein, we demonstrate covalent organic frameworks (COFs) as programmable matrices of stable organic radical qubits allowing strategic optimization of spin-phonon and spin-spin interactions. Using two classic boronate-ester frameworks, COF-5 and COF-108, to host semiquinone-like radical qubits, we achieve ultralong spin relaxation time (T1 > 300 {\mu}s) at 298 K, which outperforms most molecular qubits and rivals inorganic spin defects. The suppression of spin relaxation is attributed to rigid and neutral structures as well as carbon-centered spin distributions that effectively weaken spin-phonon coupling. Employing dynamical decoupling methods to both COFs improves their quantum coherence and enables room-temperature detection of nuclear spins including 1H, 11B, and 13C. Our work establishes COFs as designer quantum materials, opening new avenues for quantum sensing of nuclear spins at room temperature.