Paper

{
  "raw_xml": "<entry>\n    <id>http://arxiv.org/abs/2603.02507v1</id>\n    <title>Measurement of a quantum system using spin-mechanical conversion</title>\n    <updated>2026-03-03T01:37:56Z</updated>\n    <link href='https://arxiv.org/abs/2603.02507v1' rel='alternate' type='text/html'/>\n    <link href='https://arxiv.org/pdf/2603.02507v1' rel='related' title='pdf' type='application/pdf'/>\n    <summary>Levitated macroscopic particles exhibiting quantum mechanical effects are garnering increased attention as a means for precision sensing and testing quantum mechanics. Defects in diamond, such as the nitrogen-vacancy (NV) centre possess optically-addressable spins with long coherence times at room temperature and offer an intriguing system to examine quantum spin dynamics coupled to a macroscopic classical particle. In this work, we convert the outcome of a quantum measurement on an ensemble of spins into a macroscopic rotation of the host particle via spin-mechanical coupling. Following a sequence of green laser and microwave control pulses, spin-mechanical coupling between the final qubit spin state and the host particle -- an electrically-levitated diamond -- exerts a torque on the particle that deflects a weak near-infra-red laser beam. We measure spin readout contrast in excess of 70\\%, and demonstrate pulsed mechanical detection of coherent Rabi oscillations, spin-echo interferometry and $T_1$-induced relaxation. We directly measure with temporal resolution the particle reorientation from a 60\\,attonewton-metre spin torque induced by flipping the spins. Our results open up interesting new opportunities for levitated spin-mechanical systems using pulsed control, from improved sensing to the prospect of realising macroscopic quantum superposition states.</summary>\n    <category scheme='http://arxiv.org/schemas/atom' term='quant-ph'/>\n    <published>2026-03-03T01:37:56Z</published>\n    <arxiv:comment>Manuscript + Supplement, 21pgs total, 4 main figs, 6 supp figs. Comments welcome</arxiv:comment>\n    <arxiv:primary_category term='quant-ph'/>\n    <author>\n      <name>A. A. Wood</name>\n    </author>\n    <author>\n      <name>D. S. Rice</name>\n    </author>\n    <author>\n      <name>T. Xie</name>\n    </author>\n    <author>\n      <name>F. H. Cassells</name>\n    </author>\n    <author>\n      <name>R. M. Goldblatt</name>\n    </author>\n    <author>\n      <name>T. Delord</name>\n    </author>\n    <author>\n      <name>G. Hétet</name>\n    </author>\n    <author>\n      <name>A. M. Martin</name>\n    </author>\n  </entry>"
}