On one asymptotic property of time-shift quantum cryptography

One of the basic results of classical information theory is that error-free information transmission is possible even through an imperfect binary communication channel with noise up to an error of Q _c = 1/2. There is a fundamental and applied question of whether quantum-mechanical constraints can ensure error-free classical-information transmission with quantum states and, moreover, guarantee the security of distributed keys up to the theoretical limit in the error Q _c. It has been shown that the secure key distribution is possible up to the error Q _c in the asymptotic limit of a large number of bases.