1. Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 B.T. Road, Kolkata 700108, India
2. Electronics and Communication Sciences Unit, Indian Statistical Institute, 203 B.T. Road, Kolkata 700108, India
3. Department of Physics, A. B. N. Seal College, Cooch Behar, West Bengal 736101, India
4. QICI Quantum Information and Computation Initiative, Department of Computer Science, The University of Hong Kong, 999077 Pokfulam Road, Hong Kong