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Continuous-variable entanglement on a chip

Nature Photonics volume 9, pages 316–319 (2015)Cite this article

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Abstract

Encoding quantum information in continuous variables, as the quadrature of electromagnetic fields, is a powerful approach to quantum information science and technology1. Continuous-variable entanglement (light beams in Einstein–Podolsky–Rosen, or EPR2, states) is a key resource for quantum information protocols3 and enables hybridization between continuous-variable and single-photon discrete-variable qubit systems4. However, continuous-variable systems are currently limited by their implementation in free-space optical networks, and the demand for increased complexity, low loss, high-precision alignment and stability, as well as hybridization, require an alternative approach. Here we present an integrated photonic implementation of the key capabilities for continuous-variable quantum technologies—the generation and characterization of EPR beams in a photonic chip. When combined with integrated squeezing and non-Gaussian operations, these results will open the way to universal quantum information processing with light.

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Figure 1: Experimental set-up.
Figure 2: On-chip homodyne detection of squeezing.
Figure 3: EPR entanglement verification.

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References

  1. O'Brien, J. L., Furusawa, A. & Vučković, J. Optical quantum computing. Nature Photon. 3, 687–695 (2009).

    Article  ADS  Google Scholar 

  2. Einstein, A., Podolsky, B. & Rosen, N. Can quantum-mechanical description of physical reality be considered complete? Phys. Rev. 47, 777–780 (1935).

    Article  ADS  Google Scholar 

  3. Braunstein, L. & van Loock, P. Quantum information with continuous variables. Rev. Mod. Phys 77, 513–577 (2005).

    Article  ADS  MathSciNet  Google Scholar 

  4. Furusawa, A. & van Loock, P. Quantum Teleportation and Entanglement: A Hybrid Approach to Optical Quantum Information Processing (Wiley-VCH Verlag, 2011).

    Book  Google Scholar 

  5. Dowling, J. P. & Milburn, G. J. Quantum technology: the second quantum revolution. Phil. Trans. R. Soc. Lond. A 361, 1655–1674 (2003).

    Article  ADS  MathSciNet  Google Scholar 

  6. Bouwmeester, D. et al. Experimental quantum teleportation. Nature 390, 575–579 (1997).

    Article  ADS  Google Scholar 

  7. O'Brien, J. L. Optical quantum computing. Science 318, 1567–1570 (2007).

    Article  ADS  Google Scholar 

  8. Furusawa, A. et al. Unconditional quantum teleportation. Science 282, 706–709 (1998).

    Article  ADS  Google Scholar 

  9. Weedbrook, C. et al. Gaussian quantum information. Rev. Mod. Phys. 84, 621–669 (2012).

    Article  ADS  Google Scholar 

  10. Jeong, H. et al. Generation of hybrid entanglement of light. Nature Photon. 8, 564–569 (2014).

    Article  ADS  Google Scholar 

  11. Morin, O. et al. Remote creation of hybrid entanglement between particle-like and wave-like optical qubits. Nature Photon. 8, 570–574 (2014).

    Article  ADS  Google Scholar 

  12. Takeda, S. et al. Deterministic quantum teleportation of photonic quantum bits by a hybrid technique. Nature 500, 315–318 (2013).

    Article  ADS  Google Scholar 

  13. Politi, A., Cryan, M. J., Rarity, J. G., Yu, S. & O'Brien, J. L. Silica-on-silicon waveguide quantum circuits. Science 320, 646–649 (2008).

    Article  ADS  Google Scholar 

  14. Matthews, J. C. M., Politi, A., Stefanov, A. & O'Brien, J. L. Manipulation of multiphoton entanglement in waveguide quantum circuits. Nature Photon. 3, 346–350 (2009).

    Article  ADS  Google Scholar 

  15. Shadbolt, P. J. et al. Generating, manipulating and measuring entanglement and mixture with a reconfigurable photonic circuit. Nature Photon. 6, 45–49 (2012).

    Article  ADS  Google Scholar 

  16. Laing, A. et al. High-fidelity operation of quantum photonic circuits. Appl. Phys. Lett. 97, 211109 (2010).

    Article  ADS  Google Scholar 

  17. Duan, L.-M., Giedke, G., Cirac, J. I. & Zoller, P. Inseparability criterion for continuous variable systems. Phys. Rev. Lett. 84, 2722–2725 (2000).

    Article  ADS  Google Scholar 

  18. Simon, R. Peres–Horodecki separability criterion for continuous variable systems. Phys. Rev. Lett. 84, 2726–2729 (2000).

    Article  ADS  Google Scholar 

  19. Zhang, T. C., Goh, K. W., Chou, C. W., Lodahl, P. & Kimble, H. J. Quantum teleportation of light field. Phys. Rev. A 67, 033802 (2003).

    Article  ADS  Google Scholar 

  20. Sprengers, J. P. et al. Waveguide superconducting single-photon detectors for integrated quantum photonic circuits. Appl. Phys. Lett. 99, 181110 (2011).

    Article  ADS  Google Scholar 

  21. Pernice, W. H. P. et al. High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits. Nature Commun. 3, 1325 (2012).

    Article  ADS  Google Scholar 

  22. Dakna, M., Anhut, T., Opatrný, T., Knöll, L. & Welsch, D.-G. Generating Schrödinger-cat-like states by means of conditional measurements on a beam splitter. Phys. Rev. A 55, 3184–3194 (1997).

    Article  ADS  Google Scholar 

  23. Campbell, J. C. Recent advances in telecommunications avalanche photodiodes. J. Lightw. Technol. 25, 109–121 (2007).

    Article  ADS  Google Scholar 

  24. Takeda, S. et al. Quantum mode filtering of non-Gaussian states for teleportation-based quantum information processing. Phys. Rev. A 85, 053824 (2012).

    Article  ADS  Google Scholar 

  25. Suzuki, S., Yonezawa, H., Kannari, F., Sasaki, M. & Furusawa, A. 7 dB quadrature squeezing at 860 nm with periodically poled KTiOPO4 . Appl. Phys. Lett. 89, 061116 (2006).

    Article  ADS  Google Scholar 

  26. 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, 4321–7327 (2007).

    Article  ADS  Google Scholar 

  27. Masada, G. et al. Efficient generation of highly squeezed light with periodically poled MgO:LiNbO3 . Opt. Express 18, 13114–13121 (2010).

    Article  ADS  Google Scholar 

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Acknowledgements

The authors thank H. Bachor for advice. This work was partly supported by the Project for Developing Innovation Systems (PDIS), Grants-in-Aid for Scientific Research (GIA) and the Advanced Photon Science Alliance (APSA) commissioned by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, the Nippon Telegraph and Telephone Corporation (NTT), the Engineering and Physical Sciences Research Council (EPSRC), the European Research Council (ERC), Photonic Integrated Compound Quantum Encoding (PICQUE), Breaking the Barriers of Optical Integration (BBOI), the US Army Research Office (ARO; grant no. W911NF-14-1-0133) and the US Air Force Office of Scientific Research (AFOSR). J.L.O. acknowledges a Royal Society Wolfson Merit Award and a Royal Academy of Engineering Chair in Emerging Technologies.

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Authors and Affiliations

  1. Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656, Tokyo, Japan

    Genta Masada, Kazunori Miyata & Akira Furusawa

  2. Quantum ICT Research Institute, Tamagawa University, 6-1-1 Tamagawa Gakuen, Machida, 194-8610, Tokyo, Japan

    Genta Masada

  3. School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK

    Alberto Politi

  4. NTT Device Technology Laboratories, 3-1, Morinosato, Wakamiya, Atsugi, 243-0198, Kanagawa, Japan

    Toshikazu Hashimoto

  5. H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, Centre for Quantum Photonics, University of Bristol, Merchant Venturers Building, Woodland Road, Bristol, BS8 1UB, UK

    Jeremy L. O'Brien

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  1. Genta Masada
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  2. Kazunori Miyata
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  5. Jeremy L. O'Brien
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  6. Akira Furusawa
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Contributions

A.F. and J.L.O. planned the project. A.F. supervised the project. G.M. and K.M. conducted the experiment and data analysis. J.L.O. and A.P. developed the waveguide chip. T.H. provided experimental information. G.M., A.P., J.L.O. and A.F. wrote the manuscript with assistance from T.H. and K.M.

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Correspondence to Akira Furusawa.

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The authors declare no competing financial interests.

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Masada, G., Miyata, K., Politi, A. et al. Continuous-variable entanglement on a chip. Nature Photon 9, 316–319 (2015). https://doi.org/10.1038/nphoton.2015.42

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