The reversibility and determinism in quantum computing

Mika Hirvensalo

Swathi Mummadi, Bhawana Rudra

Quantum is an emerging technology in future computers. Reversibility is the main advantage of quantum computers. In conventional computers, the computation is irreversible i.e. the input bits are lost once the logic block generates the output and input bits cannot be restored but it can be done in reversible computation because in reversible computation the inputs and outputs have a one-to-one correspondence. Therefore, a reversible gate input could even be uniquely determined from their output which leads to less power consumption. Hence the complexity of the digital circuits can be reduced by using reversible computing. In quantum computer to perform reversible operations, we need to implement the reversible gates using quantum gates. In this paper, we discussed various reversible logic gates like Feynman, Toffoli, R, Peres and TR gates using basic quantum gates like CNOT, Pauli, Swap gates and their implementation using IBM quantum experience.

Nely Plata César, J. Raymundo Marcial‐Romero, José Antonio Hernández Servín

We present an extension of the denotational semantic model of the quantum programming language QML, to which computational reversibility is incorporated. The semantics of QML is defined in a functional setting which consider classical and quantum data, to which we add inverse functions. Additionally we incorporate into the semantics a history track which allows reversibility in QML. From the generation and processing of the history track and the final result of a program, the rules for executing reversibility allow to compute the original input data. This work contributes to the study of reversibility in quantum programming languages and considering that there is not yet a quantum computer in which the language can be implemented, this history and the proposed inverse functions are not trivial and allow us to determine that this language is reversible.

João Leão

Patthi Aruna, Gurumurthy Komanapalli

Low power architectures are more pronounced for different applications that extend from Internet of Things to Quantum computing. Primitive combinational logic circuits induce from bit deletion due to information loss during the processing of input information which results in energy loss. The computations involving reversibility cancel the loss of information by sustaining the input bits from output. In the basic arithmetic and logic units, the combinational circuits play a significant role in determining the performance of the processor. The principles involved in the design of reversibility is an upcoming technology for ultra-low power applications. The reversible logic circuits furnish a thoroughly new way to progress in Quantum computing. In this article, we propose an energy tolerant low power reversible multiplexer with optimum energy loss. The proposed multiplexer also reduces the ancillae, garbage outputs and quantum cost considerably.

Giuseppe Sergioli