Clifford+T-based Fault-Tolerant Quantum Implementation of Code Converter Circuit

Design of high-scalable quantum information processor (QIP) towards achieving quantum supremacy is still now in infancy due to catastrophic obstacles from decoherence. In way to address this problem, the use of quantum error correction code (QECC) and fault-tolerant circuit is highly enticieable, which further promises not only to protect extreme fragile quantum state from decoherence but also from other noises. It is seen that the fault-tolerant property can be achieved by the use of transversal primitive unitary operators. Here, we show the design of fault-tolerant implementation of BCD-to-Excess-3 and 2’s complement code converter which is pivotal in the design of high-scalable QIP. In this transformation process, first we transform the input circuit to an intermediate form where we obtain its NCV-based representation. In the second phase, this design is extensively used to form the fault-tolerant design. We also have compared our design with some of the existing works and have registered 39% improvement in design cost. In terms of T-count and T-depth metrics, our proposed designs also provide near-optimal solution.