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Optical entanglement of co-propagating modes

Abstract

Optical entanglement is a key requirement for many quantum communication protocols1. Conventionally, entanglement is formed between two distinct beams, with the quantum correlation measurements being performed at separate locations. Such setups can be complicated, requiring the repeated combination of complex resources, a task that becomes increasingly difficult as the number of entangled information channels, or modes, increases. We pave the way towards the realization of optical multimode quantum information systems by showing continuous variable entanglement between two spatial modes within one beam. Our technique is a major advance towards practical systems with minimum complexity. We demonstrate three major experimental achievements. First, only one source is required to produce squeezed light in two orthogonal spatial modes. Second, entanglement is formed through lenses and beam rotation, without the need for a beamsplitter. Finally, quantum correlations are measured directly and simultaneously using a multipixel quadrant detector.

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Figure 1: Multimode squeezing.
Figure 2: Multimode entanglement and detection.
Figure 3: Noise measurements.
Figure 4: Results for inseparability.

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References

  1. Gisin, N. & Thew, R. Quantum communication. Nature Photon 1, 165–171 (2007).

    Article  ADS  Google Scholar 

  2. Reid, M. D. et al. The Einstein–Podolsky–Rosen paradox—a fundamental challenge and a tool for quantum engineering. Rev. Mod. Phys. (accepted); <http://arXiv:0806.0270> (2008).

  3. Lee, H., Ahn, D. & Hwang, S. W. Dense coding in entangled states. Phys. Rev. A 66, 024304 (2002).

    Article  ADS  MathSciNet  Google Scholar 

  4. Bowen, W. P., Schnabel, R., Lam, P. K. & Ralph, T. C. An experimental investigation of criteria for continuous variable entanglement. Phys. Rev. Lett. 90, 043601 (2003).

    Article  ADS  Google Scholar 

  5. Yonezawa, H., Aoki, T. & Furusawa, A. Demonstration of a quantum teleportation network for continuous variables. Nature 431, 430–433 (2004).

    Article  ADS  Google Scholar 

  6. Lance, A. et al. Continuous-variable quantum-state sharing via quantum disentanglement. Phys. Rev. A 71, 033814 (2005).

    Article  ADS  Google Scholar 

  7. Dong, R. et al. Experimental entanglement distillation of mesoscopic quantum states. Nature Phys. 4, 919–923 (2008).

    Article  ADS  Google Scholar 

  8. Hage, B. et al. Preparation of distilled and purified continuous-variable entangled states. Nature Phys. 4, 915–918 (2008).

    Article  ADS  Google Scholar 

  9. Wagner, K. et al. Entangling the spatial properties of laser beams. Science 321, 541–543 (2008).

    Article  ADS  Google Scholar 

  10. Hsu, M. T. L., Bowen, W. P., Treps, N. & Lam, P. K. Continuous-variable spatial entanglement for bright optical beams. Phys. Rev. A 72, 013802 (2005).

    Article  ADS  Google Scholar 

  11. Delaubert, V. Quantum Imaging with a Small Number of Transverse Modes. PhD thesis, ANU, CNRS (2007).

    Google Scholar 

  12. Yukawa, M., Ukai, R., van Loock, P. & Furusawa, A. Experimental generation of four-mode continuous-variable cluster states. Phys. Rev. A 78, 012301 (2008).

    Article  ADS  Google Scholar 

  13. Su, X. et al. Experimental preparation of quadripartite cluster and Greenberger–Horne–Zeilinger entangled states for continuous variables. Phys. Rev. Lett. 98, 070502 (2007).

    Article  ADS  Google Scholar 

  14. Menicucci, N. C., Flammia, S. T., Zaidi, H. & Pfister, O. Ultracompact generation of continuous-variable cluster states. Phys. Rev. A 76, 010302 (2007).

    Article  ADS  MathSciNet  Google Scholar 

  15. Huntington, E. H., Milford, G. N., Robilliard, C. & Ralph, T. C. Coherent analysis of quantum optical sideband modes. Opt. Lett. 30, 2481–2483 (2005).

    Article  ADS  Google Scholar 

  16. de Valcarcel, G. J., Patera, G., Treps, N. & Fabre, C. Multimode squeezing of frequency combs. Phys. Rev. A 74, 061801 (2006).

    Article  ADS  Google Scholar 

  17. Lassen, M. et al. Generation of squeezing in higher order Hermite–Gaussian modes with an optical parametric amplifier. J. Eur. Opt. Soc. 1, 06003 (2006).

    Article  Google Scholar 

  18. Treps, N. et al. Surpassing the standard quantum limit for optical imaging using nonclassical multimode light. Phys. Rev. Lett. 88, 203601 (2002).

    Article  ADS  Google Scholar 

  19. Lassen, M. et al. Tools for spatial multi-mode quantum information: modulation, detection and quantum correlations. Phys. Rev. Lett. 98, 083602 (2007).

    Article  ADS  Google Scholar 

  20. Beck, M. Quantum state tomography with array detectors. Phys. Rev. Lett. 84, 5748–5751 (2000).

    Article  ADS  Google Scholar 

  21. Lugiato, L. A. & Gatti, A. Spatial structure of a squeezed vacuum. Phys. Rev. Lett. 70, 3868–3871 (1993).

    Article  ADS  Google Scholar 

  22. Janousek, J. Investigation of Non-classical Light and its Application in Ultrasensitive Measurements. PhD thesis, DTU (2007).

    Google Scholar 

  23. Hsu, M. T. L., Bowen, W. P. & Lam, P. K. Spatial-state Stokes-operator squeezing and entanglement for optical beams. Phys. Rev. A 79, 043825 (2009).

    Article  ADS  Google Scholar 

  24. Lassen, M., Leuchs, G. & Andersen, U. L. Continuous variable entanglement and squeezing of orbital angular momentum states. Phys. Rev. Lett. 102, 163602 (2009).

    Article  ADS  Google Scholar 

  25. Siegman, A. Lasers (University Science, 1986).

    Google Scholar 

  26. 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 

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Acknowledgements

We would like to thank A. Dreau for her contributions to the design of the data aquisition system. This work was funded by the Centre of Excellence program of the Australian Research Council. It was supported by the ANU, CNRS and the Ecole Normale Superieur, Paris. We acknowledge the financial support of the Future and Emerging Technologies (FET) programme within the Seventh Framework Programme for Research of the European Commission, under the FET-Open grant agreement HIDEAS, number FP7-ICT-221906.

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Janousek, J., Wagner, K., Morizur, JF. et al. Optical entanglement of co-propagating modes. Nature Photon 3, 399–402 (2009). https://doi.org/10.1038/nphoton.2009.97

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