Paper

{
  "raw_xml": "<entry>\n    <id>http://arxiv.org/abs/2603.16487v1</id>\n    <title>Achieving Sub-Zeptonewton Force Sensitivity and Spin-Motion Entanglement in Levitated Diamond via Pulsed Backaction Evasion</title>\n    <updated>2026-03-17T13:14:57Z</updated>\n    <link href='https://arxiv.org/abs/2603.16487v1' rel='alternate' type='text/html'/>\n    <link href='https://arxiv.org/pdf/2603.16487v1' rel='related' title='pdf' type='application/pdf'/>\n    <summary>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.</summary>\n    <category scheme='http://arxiv.org/schemas/atom' term='quant-ph'/>\n    <published>2026-03-17T13:14:57Z</published>\n    <arxiv:comment>15 pages. 7 figures</arxiv:comment>\n    <arxiv:primary_category term='quant-ph'/>\n    <author>\n      <name>Gayathrini Premawardhana</name>\n    </author>\n    <author>\n      <name>Jonathan Beaumariage</name>\n    </author>\n    <author>\n      <name>M. V. Gurudev Dutt</name>\n    </author>\n    <author>\n      <name>David Pekker</name>\n    </author>\n    <author>\n      <name>Thomas Purdy</name>\n    </author>\n    <author>\n      <name>Jacob M. Taylor</name>\n    </author>\n  </entry>"
}