Reversible adder/subtractor with overflow detector

This paper presents an efficient way to realize a reversible n-bit subtractor circuit incorporating a reversible full adder based on 2's Complement computation. We propose a reversible controlled adder/subtractor (RCAS) block used in a construction of an adder/subtractor where the negative numbers are transformed to 1's Complement number. Our circuit is better than existing ones in terms of quantum cost and garbage outputs. Moreover, we propose a novel design to detect an overflow in 2's Complement computation using modified RCAS block.