Optics: measuring and testing – By light interference
Reexamination Certificate
2001-03-27
2002-11-19
Kim, Robert H. (Department: 2882)
Optics: measuring and testing
By light interference
C356S484000
Reexamination Certificate
active
06483592
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
No related application is known.
BACKGROUND OF THE INVENTION
The present invention relates, in general, to optical communications and, more particularly, to a method to transmit information between entangled pairs of parametric down-converted photons.
It is clear that parametric down-converted signal and idler fields are incoherent and there is no observable interference in either the signal or idler fields separately. However the down-converted signal and idler fields do carry phase information about a coherent pump field through quantum entanglement. An earlier approach by Ou et al (reference: Z. Y. Ou, L. J. Wang, and L. Mandel, Phys. Rev. A 40, 1428, 1989) utilized a “two-particle” interferometer and a coincidence counter to show that, in coincidence, probability amplitudes for sibling signal and idler photons can provide a type of observable interference (fringing). This interference a result of the phase entanglement of the signal and idler photons with the down-converted photons in the coherent pump field.
The “two-particle” interferometer in the Ou et al experiment utilized probability amplitude wavefunction superposition and a coincidence counter to “sort” both signal and idler photons. Our apparatus is a different “two-particle” interferometer, utilizing phase sorting “pilot beams” which replace and remove the necessity of the coincidence counter in the Ou et al experiment, thereby observing interference from fringing without coincidence.
Fringing in the idler and signal beams, with this “pilot beam” provoked sorting, is observable because an “anti-fringing” component is inhibited, thereby causing the “fringing” component to be observable. Normally the fringing and the anti-fringing components completely add and balance to remove any semblance of interference. The sorting from the coincidence counter in the original Ou et al interferomter acted to remove the anti-fringe component and in the apparatus described herein the “pilot beam” sorting likewise removes the anti-fringe component.
In the apparatus described herein observable interference in the signal field can be effected by changes in the idler or pilot fields. This is a gross non-local effect. Such a non-local effect could be exploited for advantages and/or advances in quantum computing and communications.
BRIEF SUMMARY OF THE INVENTION
Communications between two spatially separated locations utilizing non-local entanglements of quantum particles, such as photons, has promise of being much faster than communications through other known means of transmission. The present invention provides the ability to communicate information, non-locally, between entangled signal and idler photons that are generate by a parametric down-conversion process.
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Z. Y. Ou, L. J. Wang, and L. Mandel, Phys. Rev. A40, 1428 (1989).
P. Grangier, M. J. Potasek, and B. Yurke, Phys. Rev. A38, 3132 (1988).
C. K. Hong, Z. Y. Ou, L. Mandel, Phys. Rev. Lett. 59, 2044 (1987).
P. G. Kwiat, A. M. Steinberg, R. Y. Chiao, Phys. Rev. A45, 7729, (1992).
M. M. Fejer, Physics Today, May (1994), pp25.
Z. Y. Ou, L. J. Wang, X. Y. Zou, and L. Mandel, Phys Rev. A41, 566 (1990).
Kiknadze Irakli
Kim Robert H.
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