An efficient design of 4-bit serial input parallel output/serial output shift register in quantum-dot cellular automata

The VLSI technology that is in place today caters to almost all technology based products but as the need for speed and space increases VLSI technology might not be able to keep up with the demand. There are a lot of alternatives that are being researched on but very few can match VLSI in terms of performance. Technologies such as nanotechnology, photonics, quantum computing look promising in that regard. Quantum-dot Cellular Automata(QCA) is one such technology which possibly can replace VLSI at the same time provides higher processing speed while occupying lesser space. In this paper we propose a design for
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Serial Input Parallel Output (SlPO)and
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Serial Input Serial Output (SISO) registers with the help of QCA technology.