A Review on Quantum Circuits: Qubits, Qudits, Reversible Logic Circuits and its Applications

Quantum Computing has usage in every other domain, for implementing various algorithms, systems, and many more. It has also drawn interest of many tech giants like IBM, Microsoft, Google. The reason why, quantum computing is exponentially growing is the fact, the phenomenon of superposition which is present i.e. the intrinsic parallelism in the quantum systems. The reason for the development of quantum computer was that the classical computing was reaching its limit and many problems were not solved because through classical computing approach it would take thousands of years to solve. So, there was a need for extension of the current computing scenario. This lead to the development of quantum computers. In this review we talk about various physical implementations of Quantum Bits (qubits). Further we talk about the reversible logic gates and how they are used for implementing reversible circuits. II. Quantum Bits (Qubits): Lie we have classical bit i.e. 0 or 1, in the classical or conventional computer, in a similar fashion, quantum bit or qubit is analogous to classical bit. So, we can say that qubit is nothing but a box which contains information about the quantum systm in the quantum computer. The classical bit and qubit differ on various platforms and one such platform is the property which they offer. The qubits offer the property of quantum superposition and quantum entanglement, when compared with classical bits. The qubit can be in linear combination of all possible states at the same time,