Quantum logic gates

We discuss the strategies to construct logic gates based on solid-state and molecular structures in which information transformation processes are governed by quantum mechanical principles and which, similarly to the classical complementary metal–oxide–semiconductor (CMOS) structures, do not consume power in the stationary state. In the first-generation quantum analogs of CMOS gates, logical state switching occurs by fast quantum mechanical tunneling processes, but the transfer characteristics are determined by classical diffusion–drift carrier transport. The second-generation quantum analogs of CMOS systems are open quantum systems in which charge carrier transport occurs coherently. The development of atomic-precision lithography will allow wide use of quantum molecular logic gates in traditional computer architectures.