The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 04, 2011
Filed:
Jul. 22, 2005
Xianping Sun, Wuhan, CN;
Jun Luo, Wuhan, CN;
Mingsheng Zhan, Wuhan, CN;
Abstract
The present invention discloses a free-space quantum communication device with atomic filters which are used in the field of quantum cryptography. The free-space quantum communication device of the present invention includes a beam splitter (), two λ/2 wave plates (), a λ/4 wave plate (), two polarization beam splitters (), two atomic filters (), two light couplers (), two optical fibers () and two single-photon detectors (). In the present invention, the interference filter used in the conventional quantum communication device is replaced by ultra-narrow line-width atomic filters. As the pass-band width of atomic filter is narrower than that of the interference filter in magnitude order of 3 and a light noise rejection ratio of 10can be obtained, error rate generated by background light noise can be reduced by magnitude order of 2-3. Further, the distance for carrying out free-space quantum communication can be increased. Moreover, the free-space quantum cryptography communication device can normally operate in a good manner under background light noise with sunlight or moonlight.