Single electron-photon logic device using coupled-quantum dots: Computation with the Fock ground state

We propose a novel logic device using coupled quantum dots (CQDs) in which single-electron tunneling is influenced by electron-electron interaction. If occupation/unoccupation by a single electron in a quantum dot is viewed as a bit 1/0, we can say that the device can perform (N)AND and (N)OR operations simultaneously. Data input/output is performed by irradiation/absorption of photons. The (N)AND and (N)OR operations are performed by the relaxation of the electronic system to the (Fock) ground state which depends on the number of electrons in CQDs. When the device is constructed of semiconductor nanostructures, phonon emission from an electron is the main contributor to the energy dissipation process. We also present results of a theoretical analysis of the device performance. These results show that (i) the error probability at the final state depends on only the dissipation energy and becomes smaller as the dissipation energy becomes larger, and (ii) the speed of operation depends on the dissipation energy and dissipative interactions and becomes slower as the dissipation energy becomes larger if LA-phonon emission is taken into account. If the size of the dot is 10 nm, the speed of operation and the error probability are estimated to be about 10 ps and about 0.2 at 77 K, respectively. The basic idea of the device is applicable to two-dimensional (2D) pattern processing if the devices are arranged in a 2D array. (C) 1996 American Institute of Physics.