Digital Logic Elements for Optical Computing

ツンデウオ ラウ, Tjundewo Lawu

Joseph W. Haus, C. M. Bowden, Chi C. Sung

Samyukta A Hassan, Preeta Sharan

Energy can neither be created nor be destroyed but it can be conserved. The processors of present day computers are designed using conventional logic circuits which are irreversible in nature. They suffer from loss of information during computation, leading to energy dissipation in the form of heat affecting the performance and life of the circuits. These limitations of conventional logic circuits can be overcome by the reversible logic circuits designed using quantum gates, the essential elements for quantum computing. Quantum computing is an emerging area of research which finds application in optical computing, DNA computing, cryptography, low power CMOS design, digital signal processing and nanotechnology.

Harvard Scott Hinton, John R. Erickson, Tom J. Cloonan +3 more

변영태, 김재헌, Nam‐Gyu Park +2 more

М. В. Тиханський, Andrii Partyka, Р. Р. Крисько

Using of traditional logic elements in digital electronics has ensured the development of a wide range of electronic devices for many years. In parallel, research and development of logical elements are carried out on the basis of other non-traditional physical phenomena or effects, in particular logic elements based on the phenomenon of superconductivity, the prospect of which is the use of very small energy consumption and ultrahigh performance. For superconducting logic elements, using various Josephson cryoelectronic structures, known as Josephson cryotrons, based on the stationary and non-stationary effects of Josephson. On the basis of the Josephson cryotrons, one can create Josephson elements of computer memory, and Josephson elements of digital logic. The main requirements for the Josephson cryotrons are a stable operating mode and high speed or short switching time. Information about the mode of operation and the speed give us the transition characteristics of the cryotrons - the time dependence of the voltage on the cryotron while changing its logical state, which can be obtained either experimentally, or theoretically. This work aims at a search for new ways of increasing the switching rate of digital logical operators by employing physical structures other than the traditional semiconductor-based schemes. We propose the principles of designing digital logical operators based on Josephson cryotrons, whose operation utilizes the stationary and dynamical Josephson effects, and describe the operational principles of the logical elements “AND” and “OR” bases on tunneling Josephson junctions “superconductor-insulator-superconductor”. Our proposed mathematical models for the commutation processes in such logical elements allowed us to calculate their transition characteristics during the switching and to determine the main parameters in such models. It was shown that the logical elements “AND” and “OR” can be implemented on individual cryotrons and that their logical state can be controlled by input signals in a form of current pulses. Such logical elements meet all the requirements for digital logical elements and have switching time of about 2-3 ps, which indicates their significantly increased switching rate.