Minimization of a reversible quantum 2n-to-n BCD priority encoder

In this paper, we propose a reversible quantum 2ⁿ_ to-n BCD priority encoder circuit, where n is the number of output bits. The proposed design of the 2ⁿ-to-n BCD priority encoder circuit shows that it is composed of quantum circuits for OR operation and quantum NOT gates. We present an algorithm to construct a minimized quantum 2ⁿ-to-n BCD priority encoder circuit. A technique to calculate the quantum gate complexity of quantum circuits has also been proposed in the paper. Our circuit performs better than the existing ones in terms of quantum gates, delays, garbage outputs, constant inputs, quantum gate calculation complexity, area and power, e.g., the proposed quantum 8-to-3 BCD priority encoder circuit improves 41.25% on the number of quantum gates, 46.05% on delays, 48% on garbage outputs, 60% on constant inputs and 41.25% on area and power than the existing circuit. We also simulate the proposed quantum BCD priority encoder circuit using Microwind DSCH 2.7 which shows the functional correctness of the circuit.