Abstract:
A gear set according to the present invention includes a plurality of gears which is engaged with each other. The gear set includes first to eighth gears. The first to eighth gears are arranged on each plane forming a regular octahedron.
Abstract:
A quantum cryptography system is provided to enhance an operation stability of the cryptography system by compensating for a phase variation caused by a temperature variation between 0 and 30 degrees. A quantum cryptography system includes a transmitter(110) and a receiver(130), which are coupled with each other using a quantum channel(120). The transmitter includes a first optical fiber array, a first phase modulator, and an attenuator. The first optical fiber array includes long and short optical fibers. The first phase modulator modulates the signal on the long optical fiber. The attenuator generates two quanta from two signals, which are generated due to a path difference in the first optical fiber array. The receiver includes a second optical fiber array, a second phase modulator, and a detector. The second phase modulator modulates the signal on the long optical fiber. The detector detects the interference between the signals from the second optical fiber array.
Abstract:
A direct transmission-type quantum encryption system based on phase-stabilized optical fibers is provided to coat the optical fibers with liquid crystal polymer materials, thereby configuring a stabilized quantum encryption one-way transmission system without a phase shift. Optical fibers(70), which are portions corresponding to inner optical systems of a transmitter and a receiver, are coated with liquid crystal polymer material, having negative thermal expansivity, in certain thickness, so that a phase shift caused by room temperature can be automatically compensated by positive thermal expansivity of the existing optical fibers and the negative thermal expansivity.