| 摘要 |
Quantum cryptography is a new method, which is secure against interception, for transmitting random keys by way of publicly accessible optical information channels, the low transmission speeds of which are to be increased. This has been achieved by using electro-optical liquid crystal modulators to change the polarization, these being in the form of electrically rotatable delay panels, the two double-refracting axes of which being rotated by the electrical field that is applied through an angle .theta., the size of which is a function of the strength of said field, as a result of which a .lambda./2 delay panel rotates elliptically polarized light that falls on the plate through the angle 2.theta., in the microsecond range. The area of application for the present invention is the transmission of data, secure against being intercepted, by way of publicly accessible transmission lines.
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