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arXiv · 2603.16487

Achieving Sub-Zeptonewton Force Sensitivity and Spin-Motion Entanglement in Levitated Diamond via Pulsed Backaction Evasion

Gayathrini Premawardhana·Jonathan Beaumariage·M. V. Gurudev Dutt·David Pekker·Thomas Purdy·Jacob M. Taylor
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Abstract

We propose a system to achieve sub-zeptonewton force sensing and robust spin-mechanical entanglement in a levitated diamond system. By coupling a nitrogen-vacancy (NV) center spin to the motion of its host diamond within a magnetic trap, we develop a platform designed to surpass the standard quantum limit. We develop and compare three distinct pulse sequences -- Ramsey, Hahn echo, and Carr-Purcell-Meiboom-Gill (CPMG) -- to create increasing amounts of backaction evasion while mitigating the effects of shot noise and thermal decoherence. Our results show that the CPMG sequences yield the most significant performance gains, reaching a force sensitivity of better than $10^{-23} \text{ N}/\sqrt{\text{Hz}}$ for broadband sensing around $10^4 \text{ Hz}$. Furthermore, we derive an entanglement witness protocol that accounts for pulsed dynamical decoupling, proving that spin-motion entanglement remains detectable even when occurring much faster than the mechanical period. These findings provide a more practical path for using levitated nanodiamonds both as high-precision sensors and as non-classical mechanical systems for fundamental tests of quantum mechanics.

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Gayathrini Premawardhana, Jonathan Beaumariage, M. V. Gurudev Dutt, David Pekker, Thomas Purdy, Jacob M. Taylor. 2026-03-17. Achieving Sub-Zeptonewton Force Sensitivity and Spin-Motion Entanglement in Levitated Diamond via Pulsed Backaction Evasion. https://arxiv.org/abs/2603.16487

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