Test of a majority-based reversible (quantum) 4 bits ripple-carry adder in adiabatic calculation

Quantum computing and circuits are of growing interest and so is reversible logic as it plays an important role in the synthesis of circuits dedicated to quantum computation. Moreover, reversible logic provides an alternative to classical computing machines, that may overcome many of the power dissipation problems in the near future. As a proof of concept we designed and tested a reversible 4 bits ripple-carry adder based on a do-spy-undo structure. This paper presents some performances obtained with such a chip processed in standard 0.35 μm CMOS technology and used in real reversible calculation (in this study, computations are performed in both directions such that addition and subtraction are made reversibly with the same chip). We also discuss the superiority of using adiabatic signals over classical rectangular pulses when using dual-line pass-transistor logic gates. Adiabatic signals allow the signal energy stored on the various capacitances of the circuit to be redistributed rather than being dissipated as heat. Finally, we show that adiabatic signals allow to avoid calculation errors introduced by the use of conventional rectangular pulses and allow to drastically reduce the number of pulse resynchronization in large circuits.