TOKYO -- Mitsubishi Electric Corporation (President and CEO: Tamotsu Nomakuchi) announced the successful results of their experimental quantum cryptosystem over 87km (approximately 54 miles), the longest in world, in their report titled "Quantum Cryptosystem over the distance of 87km with Absolute Security Against Cryptanalysis." This distance is roughly the same distance of that between Tokyo and Mt. Fuji. This experiment, which used a 1550nm wavelength optical fiber (a wavelength deemed suitable for long distance telecom communications) has great significance toward the realization of a practical integrated cryptosystem with absolute-security quantum and high-speed, modern cryptography. Quantum cryptography: In the microscopic world, once a system is observed, it is inevitably affected and changes into another state (Heisenberg's Uncertainty Principle). By incorporating the fact that weak light behaves as "photons" subject to this law, quantum cryptography is an unbreakable cryptography with the photons becoming the information carriers. Security of nearly all modern cryptography is evaluated on a computational complexity basis. Cryptanalysis requires extraordinary complexity or time. Therefore, it is pointed out that modern cryptography may be breakable (threatened) by the advent of high-performance computers such as quantum computers. On the other hand, quantum cryptography, which has the advantage of being able to detect eavesdropping on communication channels, is expected to be realized as an "absolutely unbreakable cryptography" compared to modern cryptography. Mitsubishi Electric & Electronics USA Inc.