Reversible Logic Synthesis of k-Input, m-Output Lookup Tables
Alireza Shafaei, Mehdi Saeedi, Massoud Pedram
Abstract
Abstract—Improving circuit realization of known quantum algorithms by CAD techniques has benefits for quantum experimentalists. In this paper, we address the problem of synthesizing a given k-input, m-output lookup table (LUT) by a reversible circuit. This problem has interesting applications in the Shor’s number-factoring algorithm and in quantum walk on sparse graphs. For LUT synthesis, our approach targets the number of control lines in multiple-control Toffoli gates to reduce synthesis cost. To achieve this, we propose a multi-level optimization technique for reversible circuits to benefit from shared cofactors. To reuse output qubits and/or zero-initialized ancillae, we uncompute intermediate cofactors. Our simulations reveal that the proposed LUT synthesis has a significant impact on reducing the size of modular exponentiation circuits for Shor’s quantum factoring algorithm, oracle circuits in quantum walk on sparse graphs, and the well-known MCNC benchmarks. Keywords-Lookup tables; Logic synthesis; Reversible circuits; Shor’s quantum number-factoring algorithm; Binary welded tree.