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Secure communications with low-orbit spacecraft using quantum cryptography

United States Patent

5,966,224
October 12, 1999
View the Complete Patent at the US Patent & Trademark Office
Los Alamos National Laboratory - Visit the Technology Transfer Division Website
Apparatus and method for secure communication between an earth station and spacecraft. A laser outputs single pulses that are split into preceding bright pulses and delayed attenuated pulses, and polarized. A Pockels cell changes the polarization of the polarized delayed attenuated pulses according to a string of random numbers, a first polarization representing a "1," and a second polarization representing a "0." At the receiving station, a beamsplitter randomly directs the preceding bright pulses and the polarized delayed attenuated pulses onto longer and shorter paths, both terminating in a beamsplitter which directs the preceding bright pulses and a first portion of the polarized delayed attenuated pulses to a first detector, and a second portion of the polarized delayed attenuated pulses to a second detector to generate a key for secure communication between the earth station and the spacecraft.
Hughes; Richard J. (Los Alamos, NM), Buttler; William T. (Los Alamos, NM), Kwiat; Paul G. (Los Alamos, NM), Luther; Gabriel G. (Los Alamos, NM), Morgan; George L (Jemez Springs, NM), Nordholt; Jane E. (Los Alamos, NM), Peterson; Charles G. (Los Alamos, NM), Simmons; Charles M. (Los Alamos, NM)
The Regents of the University of California (Los Alamos, NM)
08/ 859,187
May 20, 1997
The present invention generally relates to secure communication systems, and, more specifically, to secure communication between earth and low-orbit spacecraft. This invention was made with Government support under Contract No. W-7405-ENG-36 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.