The First Ghost Image ( II )

 Right now we are working on spatial correlation and very soon we will be able to observe the ghost image of an object mask with sunlight as a source. This result can be interpreted as a nonlocal point-to-point image-forming correlation which is the result of interference between two-photon amplitudes, corresponding to different yet indistinguishable alternative ways of triggering a joint photodetection event. As a result of two-photon interference, ghost imaging has two peculiar features:(1) it is nonlocal and (2) its spatial resolution which is better from that of classical imaging. Consequently, ghost imaging using the sun as a light source could achieve spatial resolution equivalent to that of a classical imaging system taking pictures at a distance of 10km with a 92m-diameter lens. In conclusion, this experimental demonstration of sunlight-based ghost imaging raises a fundamentally im-portant question about whether the nonlocal ghost-imaging effect of classical thermal light is caused by quantum-mechanical two-photon interference.



References
1. T.B. Pittman, Y.H. Shih, D.V. Strekalov, and A.V. Sergienko, Phys. Rev. A52, R3429 (1995).
2. A. Valencia, G. Scarcelli, M. D'Angelo, Y. H. Shih, , Phys. Rev. Lett.94, 063601 (2005); G. Scarcelli, V. Berardi, Y. H.
Shih, Phys. Rev. Lett.96, 063602(2006); R. Meyers, K. S. Deacon, Y. H. Shih, Phys. Rev. A77, 041801(2008); Y. Shih,
SPIE News, Electronic Imaging and Signal Processing, July, (2009).
3. A. Gatti, E. Brambilla, M. Bache, L. A. Lugiato, Phys. Rev. Lett.93, 093602(2004); Phys. Rev. A70, 013802(2004).
4. D. Zhang, Y. Zhai, L. Wu, X. Chen, Optics Letters30, 2354(2005).

The Fisrt Ghost Image ( I )

Ghost imaging was first demonstrated experimentally by Pittman et al.[1]in 1995 using entangled photon
pairs as the light source. Later, using a chaotic radiation or pseudo-thermal light source, a 50% contrast
ghost image of the object was observed in terms of coincidences between the CCD and a bucket detector
that receives the scattered and reflected photons from the object [2]. In 2004, Gatti et al. demonstrated
speckle-to-speckle classical correlation between two distant planes to image the speckles of the source onto
both the object and ghost-image planes [3]. In 2005, Zhang et al. demonstrated an experiment of two-photon
correlated imaging with true thermal light from a hollow cathode lamp [4]. In this paper, we wish to report
first experimental demonstration on two-photon ghost imaging using the Sun as a light source for field imaging applications.



References
1. T.B. Pittman, Y.H. Shih, D.V. Strekalov, and A.V. Sergienko, Phys. Rev. A52, R3429 (1995).
2. A. Valencia, G. Scarcelli, M. D'Angelo, Y. H. Shih, , Phys. Rev. Lett.94, 063601 (2005); G. Scarcelli, V. Berardi, Y. H.
Shih, Phys. Rev. Lett.96, 063602(2006); R. Meyers, K. S. Deacon, Y. H. Shih, Phys. Rev. A77, 041801(2008); Y. Shih,
SPIE News, Electronic Imaging and Signal Processing, July, (2009).
3. A. Gatti, E. Brambilla, M. Bache, L. A. Lugiato, Phys. Rev. Lett.93, 093602(2004); Phys. Rev. A70, 013802(2004).
4. D. Zhang, Y. Zhai, L. Wu, X. Chen, Optics Letters30, 2354(2005).