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Indistinguishable photons from a single-photon device


Single-photon sources have recently been demonstrated using a variety of devices, including molecules1,2,3, mesoscopic quantum wells4, colour centres5, trapped ions6 and semiconductor quantum dots7,8,9,10,11. Compared with a Poisson-distributed source of the same intensity, these sources rarely emit two or more photons in the same pulse. Numerous applications for single-photon sources have been proposed in the field of quantum information, but most—including linear-optical quantum computation12—also require consecutive photons to have identical wave packets. For a source based on a single quantum emitter, the emitter must therefore be excited in a rapid or deterministic way, and interact little with its surrounding environment. Here we test the indistinguishability of photons emitted by a semiconductor quantum dot in a microcavity through a Hong–Ou–Mandel-type two-photon interference experiment13,14. We find that consecutive photons are largely indistinguishable, with a mean wave-packet overlap as large as 0.81, making this source useful in a variety of experiments in quantum optics and quantum information.

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Figure 1: The single-photon source.
Figure 2: Time-averaged emission properties of quantum dots 1, 2 and 3.
Figure 3: Two-photon interference experiment.
Figure 4: The probability that two photons that collide at the beam splitter leave in opposite directions, plotted as a function of interferometer delay offset, Δt.


  1. 1

    De Martini, F., Di Giuseppe, G. & Marrocco, M. Single-mode generation of quantum photon states by excited single molecules in a microcavity trap. Phys. Rev. Lett. 76, 900–903 (1996)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Brunel, C., Lounis, B., Tamarat, P. & Orrit, M. Triggered source of single photons based on controlled single molecule fluorescence. Phys. Rev. Lett. 83, 2722–2725 (1999)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Lounis, B. & Moerner, W. E. Single photons on demand from a single molecule at room temperature. Nature 407, 491–493 (2000)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Kim, J., Benson, O., Kan, H. & Yamamoto, Y. A single-photon turnstile device. Nature 397, 500–503 (1999)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Beveratos, A. et al. Room temperature stable single-photon source. Eur. Phys. J. D 18, 191–196 (2002)

    ADS  CAS  Google Scholar 

  6. 6

    Kuhn, A., Hennrich, M. & Rempe, G. Deterministic single-photon source for distributed quantum networking. Phys. Rev. Lett. 89, 067901 (2002).

  7. 7

    Michler, P. et al. A quantum dot single-photon turnstile device. Science 290, 2282–2285 (2000)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Santori, C., Pelton, M., Solomon, G., Dale, Y. & Yamamoto, Y. Triggered single photons from a quantum dot. Phys. Rev. Lett. 86, 1502–1505 (2001)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Zwiller, V. et al. Single quantum dots emit single photons at a time: antibunching experiments. Appl. Phys. Lett. 78, 2476–2478 (2001)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Yuan, Z. et al. Electrically driven single photon source. Science 295, 102–105 (2002)

    ADS  CAS  Article  Google Scholar 

  11. 11

    Gérard, J.-M. & Gayral, B. Strong Purcell effect for InAs quantum boxes in three-dimensional solid-state microcavities. J. Lightwave Technol. 17, 2089–2095 (1999)

    ADS  Article  Google Scholar 

  12. 12

    Knill, E., Laflamme, R. & Milburn, G. J. A scheme for efficient quantum computation with linear optics. Nature 409, 46–52 (2001)

    ADS  CAS  Article  Google Scholar 

  13. 13

    Fearn, H. & Loudon, R. Theory of two-photon interference. J. Opt. Soc. Am. B 6, 917–927 (1989)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Hong, C. K., Ou, Z. Y. & Mandel, L. Measurement of subpicosecond time intervals between two photons by interference. Phys. Rev. Lett. 59, 2044–2046 (1987)

    ADS  CAS  Article  Google Scholar 

  15. 15

    Bennett, C. H. & Brassard, G. Proc. IEEE Int. Conf. on Computers, Systems and Signal Processing 175–179 (IEEE, New York, 1984)

    Google Scholar 

  16. 16

    Bouwmeester, D., Ekert, A. & Zeilinger, A. The Physics of Quantum Information 49–92 (Springer, Berlin, 2000)

    MATH  Google Scholar 

  17. 17

    Shih, Y. H. & Alley, C. O. New type of Einstein–Podolsky–Rosen–Bohm experiment using pairs of light quanta produced by optical parametric down conversion. Phys. Rev. Lett. 61, 2921–2924 (1988)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Moreau, E. et al. Single-mode solid-state single photon sources based on isolated quantum dots in pillar microcavities. Appl. Phys. Lett. 79, 2865–2867 (2001)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Solomon, G. S., Pelton, M. & Yamamoto, Y. Single-mode spontaneous emission from a single quantum dot in a three-dimensional microcavity. Phys. Rev. Lett. 86, 3903–3906 (2001)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Borri, P. et al. Ultralong dephasing time in InGaAs quantum dots. Phys. Rev. Lett. 87, 157401 (2001)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Gammon, D., Snow, E. S., Shanabrook, B. V., Katzer, D. S. & Park, D. Homogeneous linewidths in the optical spectrum of a single gallium arsenide quantum dot. Science 273, 87–90 (1996)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Bayer, M. & Forchel, A. Temperature dependence of the exciton homogeneous linewidth in In0.60Ga0.40As/GaAs self-assembled quantum dots. Phys. Rev. B 65, 041308(R) (2002)

    ADS  Article  Google Scholar 

  23. 23

    Kulakovskii, V. D. et al. Fine structure of biexciton emission in symmetric and asymmetric CdSe/ZnSe single quantum dots. Phys. Rev. Lett. 82, 1780–1783 (1999)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Besombes, L., Kheng, K., Marsal, L. & Mariette, H. Acoustic phonon broadening mechanism in single quantum dot emission. Phys. Rev. B 63, 155307 (2001)

    ADS  Article  Google Scholar 

  25. 25

    Fan, X., Takagahara, T., Cunningham, J. E. & Wang, H. Pure dephasing induced by exciton–phonon interactions in narrow GaAs quantum wells. Solid State Commun. 108, 857–861 (1998)

    ADS  CAS  Article  Google Scholar 

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We thank A. Scherer and T. Yoshie for access to the CAIBE system and for their help in fabrication of the structures; J. Plant for assistance with SEM imaging; and B. C. Sanders for discussions. This work was supported in part by MURI; G.S.S. was supported by DARPA, ARO and JST.

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Correspondence to Charles Santori.

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Santori, C., Fattal, D., Vučković, J. et al. Indistinguishable photons from a single-photon device. Nature 419, 594–597 (2002).

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