1. Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576
2. Low Energy Electronic Systems (LEES), Singapore MIT Alliance for Research and Technology (SMART), 1 CREATE Way, #10-01 CREATE Tower, Singapore 138602
3. School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798
4. Department of Physics, National University of Singapore, Singapore 117551