Photon cloning may compromise quantum cryptography

New Scientist : Although quantum cryptography has been touted as a method of secure communication, it may be susceptible to eavesdropping, according to a paper published in Physical Review Letters. Quantum cryptographic techniques rely on a fundamental principle of quantum mechanicsâmdash;namely, that the act of measuring quantum data disturbs the data. Therefore, any attempt by a hacker to intercept a message compromises the transmittal. However, even the best systems will always have some margin of error. Now a quantum cloner has been developed that can create copies of a quantum-encrypted message’s photons that, although not perfect, are good enough to keep the transmission error rate relatively low. Only by closely monitoring the rate of error can the counterfeits be detected.