Novel Reversible TSG Gate and Its Application for Designing Components   of Primitive Reversible/Quantum ALU
  In recent years, reversible logic has emerged as a promising computing paradigm having application in low power CMOS, quantum computing, nanotechnology, and optical computing. The classical set of gates such as AND, OR, and EXOR are not reversible. This paper utilizes a new 4 * 4 reversible gate called TSG gate to build the components of a primitive reversible/quantum ALU. The most significant aspect of the TSG gate is that it can work singly as a reversible full adder, that is reversible full adder can now be implemented with a single gate only. A Novel reversible 4:2 compressor is also designed from the TSG gate which is later used to design a novel 8x8 reversible Wallace tree multiplier. It is proved that the adder, 4:2 compressor and multiplier architectures designed using the TSG gate are better than their counterparts available in literature, in terms of number of reversible gates and garbage outputs. This is perhaps, the first attempt to design a reversible 4:2 compressor and a reversible Wallace tree multiplier as far as existing literature and our knowledge is concerned. Thus, this paper provides an initial threshold to build more complex systems which can execute complicated operations using reversible logic. 
Himanshu Thapliyal, M. B. Srinivas