PSO Inspired Global Neighbourhood Based Qubit Mapping: A New Approach

Due to limited connectivity between physical qubits of quantum devices, it is a real challenge to map a logical circuit to physical hardware device. To ensure proper mapping of logical qubits to physical qubits, this research introduces particle swarm optimization (PSO) inspired global neighbourhood based (GNB) qubit mapping. Starting with an empty initial mapping, degree of each logical qubit of the circuit is computed. Degree of a qubit refers to the number of qubits with which it is connected in the entire circuit. The proposed technique maps the highest degree qubit and its global neighbours initially based on the designed heuristic and then maps the remaining logical qubits in a way that minimizes the total distance to already allocated physical qubits. The concept of "global neighbours" refers to all interconnected qubits within a circuit, regardless of the direction of their connections. Thus, the proposed fitness ensures minimization of the sum of the swap count and the degree difference between logical and mapped physical qubits for the complete mapping. The swap count is determined by the distance between mapped physical qubits for each gate. PSO based implementation of GNB yields efficient mapping of benchmark circuits to physical hardware of IBM QX5 in feasible execution time. Number of operations, depth and execution time (in second) of the mapped circuit obtained from PSO is compared with the previous methodologies and also with Genetic Algorithm (GA). PSO exhibits rapid convergence speed and thus showcase its ability to find near-optimal solution in lesser time.

Speaker:

Dr. Kunal Das has received the B. Tech (Information Technology) and M. Tech (Information Technology) from Calcutta University, Kolkata, India. He was awarded a Ph.D degree from the University of Kalyani. He is a former Assistant Professor of the Department of Computer Science & Engineering, National Institute of Technology, Arunachal Pradesh, India, and Associate Professor of the Department of Computer Science & Engineering, Narual Institute of Technology, Kolkata. Currently, he working as an Assistant Professor (Sr. Gr.) at the Department of Computer Science, Acharya Prafulla Chandra College (Govt. of West Bengal), New Barrackpore, West Bengal, India. He has authored more than 50 Int. SCI journal papers, several conference papers, andreviewer of many SCI journals like Elsevier Microelectronics journal, Springer JETTA, IEEE Trans. and many international conferences. He is an Associate Editorial Board Member of the Current Chinese Computer Science journal. His research interests include Nano devices like Quantum dot Cellular Automata, VLSI design, and Digital Microfluidic BioChip. Currently, his research focus is on Quantum Computing, Quantum Machine learning, and solving optimization problems using adiabatic Quantum Computers. He also got ranked in the “World Scientist Ranking” by the AD Scientific Index. Dr. Das is supervising eight PhD scholars. Out of them, four scholars have completed, and a few have also been awarded PhD degrees.

Facilitator: Dr. Sebastian Zajac, member of QPoland