Generation and control of frequency-dependent squeezing via Einstein–Podolsky–Rosen entanglement


Quantum noise-limited displacement sensors such as gravitational wave detectors can be improved by using non-classical light1. This has been achieved in limited bands and in a single quadrature (that is, only one of a pair of conjugate variables) by injecting single-mode squeezed vacuum states2,3. Quantum noise in gravitational wave detectors, however, results from input noise in both quadratures, with the dominant quadrature being a function of Fourier frequency. Broadband reduction of this noise via squeezed light injection then requires a method of rotating this quadrature. This can be accomplished with a low-loss, all-pass optical filter with bandwidth in the low audio frequencies4,5, a substantial technical challenge. We present a proof-of-principle demonstration of a recent proposal6 to use two-mode squeezed vacuum states with Einstein–Podolsky–Rosen (EPR) entanglement, which allows the gravitational detector to simultaneously serve as the optical filter, eliminating the need for a separate apparatus.

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Fig. 1: Generation of frequency-dependent squeezing with EPR states.
Fig. 2: Noise spectrum for different test cavity detuning.
Fig. 3: Stable control of the squeezing angle.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


  1. 1.

    Kimble, H. J., Levin, Y., Matsko, A. B., Thorne, K. S. & Vyatchanin, S. P. Conversion of conventional gravitational-wave interferometers into quantum nondemolition interferometers by modifying their input and/or output optics. Phys. Rev. D 65, 022002 (2001).

    ADS  Article  Google Scholar 

  2. 2.

    Grote, H. et al. First long-term application of squeezed states of light in a gravitational-wave observatory. Phys. Rev. Lett. 110, 181101 (2013).

    ADS  Article  Google Scholar 

  3. 3.

    The LIGO Scientific Collaboration et al. Enhanced sensitivity of the LIGO gravitational wave detector by using squeezed states of light. Nat. Photon. 7, 613–619 (2013).

    Article  Google Scholar 

  4. 4.

    Oelker, E. et al. Audio-band frequency-dependent squeezing for gravitational-wave detectors. Phys. Rev. Lett. 116, 041102 (2016).

    ADS  Article  Google Scholar 

  5. 5.

    Capocasa, E. et al. Estimation of losses in a 300 m filter cavity and quantum noise reduction in the Kagra gravitational-wave detector. Phys. Rev. D 93, 082004 (2016).

    ADS  Article  Google Scholar 

  6. 6.

    Ma, Y. et al. Proposal for gravitational-wave detection beyond the standard quantum limit through EPR entanglement. Nat. Phys. 13, 776–780 (2017).

    Article  Google Scholar 

  7. 7.

    The LIGO Scientific Collaboration. Advanced LIGO. Class. Quant. Grav. 32, 074001 (2015).

  8. 8.

    The VIRGO Collaboration. Advanced VIRGO: a second-generation interferometric gravitational wave detector. Class. Quant. Grav. 32, 024001 (2015).

  9. 9.

    The LIGO Scientific Collaboration and VIRGO Collaboration. GW170817: observation of gravitational waves from a binary neutron star inspiral. Phys. Rev. Lett. 119, 161101 (2017).

  10. 10.

    Abbott, B. P. et al. Multi-messenger observations of a binary neutron star merger. Astrophys. J. Lett. 848, L12 (2017).

    ADS  Article  Google Scholar 

  11. 11.

    Caves, C. M. Quantum-mechanical noise in an interferometer. Phys. Rev. D 23, 1693–1708 (1981).

    ADS  Article  Google Scholar 

  12. 12.

    Wade, A. R. et al. Optomechanical design and construction of a vacuum-compatible optical parametric oscillator for generation of squeezed light. Rev. Sci. Instrum. 87, 063104 (2016).

    ADS  Article  Google Scholar 

  13. 13.

    Vahlbruch, H., Mehmet, M., Danzmann, K. & Schnabel, R. Detection of 15 dB squeezed states of light and their application for the absolute calibration of photoelectric quantum efficiency. Phys. Rev. Lett. 117, 110801 (2016).

    ADS  Article  Google Scholar 

  14. 14.

    Oelker, E. et al. Ultra-low phase noise squeezed vacuum source for gravitational wave detectors. Optica 3, 682–685 (2016).

    ADS  Article  Google Scholar 

  15. 15.

    Mikhailov, E. E., Goda, K., Corbitt, T. & Mavalvala, N. Frequency-dependent squeeze-amplitude attenuation and squeeze-angle rotation by electromagnetically induced transparency for gravitational-wave interferometers. Phys. Rev. A 73, 053810 (2006).

    ADS  Article  Google Scholar 

  16. 16.

    Ma, Y. et al. Narrowing the filter-cavity bandwidth in gravitational-wave detectors via optomechanical interaction. Phys. Rev. Lett. 113, 151102 (2014).

    ADS  Article  Google Scholar 

  17. 17.

    Kwee, P., Miller, J., Isogai, T., Barsotti, L. & Evans, M. Decoherence and degradation of squeezed states in quantum filter cavities. Phys. Rev. D 90, 062006 (2014).

    ADS  Article  Google Scholar 

  18. 18.

    Evans, M., Barsotti, L., Kwee, P., Harms, J. & Miao, H. Realistic filter cavities for advanced gravitational wave detectors. Phys. Rev. D 88, 022002 (2013).

    ADS  Article  Google Scholar 

  19. 19.

    Chelkowski, S. et al. Experimental characterization of frequency-dependent squeezed light. Phys. Rev. A 71, 013806 (2005).

    ADS  Article  Google Scholar 

  20. 20.

    Brown, D. D. et al. Broadband sensitivity enhancement of detuned dual-recycled Michelson interferometers with EPR entanglement. Phys. Rev. D 96, 062003 (2017).

    ADS  Article  Google Scholar 

  21. 21.

    Südbeck, J., Steinlechner, S., Korobko, M. & Schnabel, R. Demonstration of interferometer enhancement through Einstein–Podolsky–Rosen entanglement. Nat. Photon. (2020).

  22. 22.

    Hage, B., Samblowski, A. & Schnabel, R. Towards Einstein–Podolsky–Rosen quantum channel multiplexing. Phys. Rev. A 81, 062301 (2010).

    ADS  MathSciNet  Article  Google Scholar 

  23. 23.

    Zhang, J. Einstein–Podolsky–Rosen sideband entanglement in broadband squeezed light. Phys. Rev. A 67, 054302 (2003).

    ADS  Article  Google Scholar 

  24. 24.

    Li, W., Jin, Y., Yu, X. & Zhang, J. Enhanced detection of a low-frequency signal by using broad squeezed light and a bichromatic local oscillator. Phys. Rev. A 96, 023808 (2017).

    ADS  Article  Google Scholar 

  25. 25.

    Buonanno, A. & Chen, Y. Quantum noise in second generation, signal-recycled laser interferometric gravitational-wave detectors. Phys. Rev. D 64, 042006 (2001).

    ADS  Article  Google Scholar 

  26. 26.

    Vahlbruch, H. et al. Coherent control of vacuum squeezing in the gravitational-wave detection band. Phys. Rev. Lett. 97, 011101 (2006).

    ADS  Article  Google Scholar 

  27. 27.

    Chua, S. S. Y. et al. Backscatter tolerant squeezed light source for advanced gravitational-wave detectors. Opt. Lett. 36, 4680–4682 (2011).

    ADS  Article  Google Scholar 

  28. 28.

    Beckey, J. L., Ma, Y., Boyer, V. & Miao, H. Broadband quantum noise reduction in future long baseline gravitational-wave detectors via EPR entanglement. Phys. Rev. D 100, 083011 (2019).

    ADS  Article  Google Scholar 

  29. 29.

    Takeno, Y., Yukawa, M., Yonezawa, H. & Furusawa, A. Observation of −9 dB quadrature squeezing with improvement of phase stability in homodyne measurement. Opt. Express 15, 4321–4327 (2007).

    ADS  Article  Google Scholar 

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This research was supported by the Australian Research Council (ARC) under the ARC Centre of Excellence for Gravitational Wave Discovery grant number CE170100004. M.J.Y. thanks B. Buchler, G. Mansell and V. Adya for discussions.

Author information




M.J.Y. performed the investigation and formal analysis. P.A. wrote the real-time data acquisition/analysis program. M.J.Y. and D.E.M. conceptualized the project. M.J.Y. wrote the original draft. P.A., T.G.M., R.L.W. and D.E.M. reviewed and edited the manuscript. P.A., T.G.M., R.L.W., B.J.J.S. and D.E.M. provided supervision.

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Correspondence to Min Jet Yap.

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Supplementary Information

Supplementary Figs. 1 and 2 and methods.

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Yap, M.J., Altin, P., McRae, T.G. et al. Generation and control of frequency-dependent squeezing via Einstein–Podolsky–Rosen entanglement. Nat. Photonics 14, 223–226 (2020).

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