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arXiv · 2609.19317

Observing and evading quantum back-action on a kilogram-scale oscillator

Begüm Kabagöz·Eric Oelker·Dhruva Ganapathy·Nergis Mavalvala·Vivishek Sudhir·Vladimir Bossilkov·Joseph Betzweiser·Valery V. Frolov·Anamaria Effler·Adam Mullavey·Lisa Barsotti·Evan D. Hall·Peter Fritschel·R. Abbott·I. Abouelfettouh·R. X. Adhikari·A. Ananyeva·S. Appert·S. K. Apple·K. Arai·N. Aritomi·S. M. Aston·M. Ball·S. W. Ballmer·D. Barker·B. K. Berger·D. Bhattacharjee·G. Billingsley·S. Biscans·C. D. Blair·N. Bode·E. Bonilla·A. Branch·A. F. Brooks·D. D. Brown·J. Bryant·C. Cahillane·A. Calafat·S. R. Callos·H. Cao·E. Capote·F. Clara·J. Collins·C. M. Compton·G. Connolly·R. Cottingham·D. C. Coyne·R. Crouch·J. Csizmazia·A. Cumming·L. P. Dartez·D. Davis·N. Demos·E. Dohmen·K. L. Dooley·J. C. Driggers·S. E. Dwyer·A. Ejlli·T. Etzel·M. Evans·J. Feicht·R. Frey·W. Frischhertz·M. Fuentes-Garcia·P. Fulda·M. Fyffe·B. Gateley·T. Gayer·J. A. Giaime·K. D. Giardina·J. Glanzer·E. Goetz·R. Goetz·A. W. Goodwin-Jones·S. Gras·C. Gray·D. Griffith·H. Grote·T. Guidry·J. Gurs·J. Hanks·J. Hanson·M. C. Heintze·A. F. Helmling-Cornell·N. A. Holland·D. Hoyland·H. Y. Huang·Y. Inoue·A. L. James·A. Jamies·R. Jaume·A. Jennings·W. Jia·D. H. Jones·S. Karat·S. Karki·M. Kasprzack·K. Kawabe·N. Kijbunchoo·P. J. King
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Abstract

Continuous quantum displacement measurements are fundamentally limited by a trade-off between readout imprecision and measurement back-action, constrained by the Heisenberg uncertainty principle. In the Laser Interferometric Gravitational-Wave Observatory (LIGO), these two quantum noise components dominate much of the observation band, making it an excellent testbed. We induce a sub-Hz-linewidth optomechanical mode by trapping the differential motion of the 40-kg mirrors in a band where radiation-pressure back-action dominates the motion. Engineering the quantum state entering the dark port creates correlations between imprecision and back-action that partially cancel their contributions, reducing observed motion near resonance by ~47%. A framework resolving the imprecision, back-action, and correlation terms identifies the origin of this suppression. These results demonstrate quantum back-action evasion and quantum reservoir engineering in a macroscopic optomechanical system.

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Begüm Kabagöz, Eric Oelker, Dhruva Ganapathy, Nergis Mavalvala, Vivishek Sudhir, Vladimir Bossilkov, Joseph Betzweiser, Valery V. Frolov, Anamaria Effler, Adam Mullavey, Lisa Barsotti, Evan D. Hall, Peter Fritschel, R. Abbott, I. Abouelfettouh, R. X. Adhikari, A. Ananyeva, S. Appert, S. K. Apple, K. Arai, N. Aritomi, S. M. Aston, M. Ball, S. W. Ballmer, D. Barker, B. K. Berger, D. Bhattacharjee, G. Billingsley, S. Biscans, C. D. Blair, N. Bode, E. Bonilla, A. Branch, A. F. Brooks, D. D. Brown, J. Bryant, C. Cahillane, A. Calafat, S. R. Callos, H. Cao, E. Capote, F. Clara, J. Collins, C. M. Compton, G. Connolly, R. Cottingham, D. C. Coyne, R. Crouch, J. Csizmazia, A. Cumming, L. P. Dartez, D. Davis, N. Demos, E. Dohmen, K. L. Dooley, J. C. Driggers, S. E. Dwyer, A. Ejlli, T. Etzel, M. Evans, J. Feicht, R. Frey, W. Frischhertz, M. Fuentes-Garcia, P. Fulda, M. Fyffe, B. Gateley, T. Gayer, J. A. Giaime, K. D. Giardina, J. Glanzer, E. Goetz, R. Goetz, A. W. Goodwin-Jones, S. Gras, C. Gray, D. Griffith, H. Grote, T. Guidry, J. Gurs, J. Hanks, J. Hanson, M. C. Heintze, A. F. Helmling-Cornell, N. A. Holland, D. Hoyland, H. Y. Huang, Y. Inoue, A. L. James, A. Jamies, R. Jaume, A. Jennings, W. Jia, D. H. Jones, S. Karat, S. Karki, M. Kasprzack, K. Kawabe, N. Kijbunchoo, P. J. King. 2026-09-16. Observing and evading quantum back-action on a kilogram-scale oscillator. https://arxiv.org/abs/2609.19317

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