A high-speed and low-cost approximate full adder in QCA technology Seyed Erfan Fatemieh, Negin Mashayekhi and Mohammad Reza Reshadinezhad Eur. Phys. J. Plus, 140 8 (2025) 726 Published online: 04 August 2025 DOI: 10.1140/epjp/s13360-025-06668-4