  A new and simple quantum key distribution scheme based on the quantum
intensity correlation of optical twin beams and the directly local measurements
of intensity noise of single optical beam is presented and experimentally
demonstrated. Using the twin beams with the quantum intensity correlation of
5dB the effective bit rate of $2\times 10^7bits/s$ is completed. The noncloning
of quantum systems and the sensitivity of the existing correlations to losses
provide the physical mechamism for the security against eavesdropping. In the
presented scheme the signal modulation and homodyne detection are not needed.
