Long-Lived Mechanically-Detected Molecular Spins for Quantum Sensing

• URL: http://arxiv.org/abs/2603.04708v1
• Date: Thu, 05 Mar 2026 01:18:10 GMT
• Title: Long-Lived Mechanically-Detected Molecular Spins for Quantum Sensing
• Authors: Sahand Tabatabaei, Pritam Priyadarsi, Daniel Tay, Namanish Singh, Pardis Sahafi, Andrew Jordan, Raffi Budakian,
• Abstract summary: Quantum sensors based on individual spins provide unprecedented access to local magnetic fields in condensed matter, chemistry, and biology.<n>We present a nanoscale sensing platform that combines molecular electron spins, ultrasensitive mechanical readout, and Hamiltonian engineering.
• Score: 0.9368753183086049
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Quantum sensors based on individual spins provide unprecedented access to local magnetic fields in condensed matter, chemistry, and biology, with solid-state defect spins emerging as the leading platform. However, their molecular-sensing capabilities are limited by confinement to a host lattice, which prevents placement in close proximity to a target molecule. Molecular spins offer an alternative, enabling chemical tunability and flexible positioning relative to the target system. Here we present a nanoscale sensing platform that combines molecular electron spins, ultrasensitive mechanical readout, and Hamiltonian engineering. Using a modified XYXY dipolar decoupling sequence, we suppress electron-electron dipolar interactions across a broad distribution of control fields, extending coherence times to $\sim 400~μ$s in an attoliter-scale droplet containing $\sim$100 trityl-OX063 radicals. Leveraging this sequence, we demonstrate frequency-selective detection of nanotesla-scale AC fields and perform sensing and spectroscopy of small, local nuclear-spin ensembles. Collectively, these results establish SQUINT (Spin-based QUantum Integrated Nanomechanical Transduction) as a framework for quantum sensing that affords molecular-level control over sensor properties and enables direct integration into complex molecular targets.

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