[1] Harish Chandra Res Inst, Quantum Informat & Computat Grp, Chhatnag Rd, Allahabad, Uttar Pradesh, India
[2] Homi Bhabha Natl Inst, Training Sch Complex, Bombay 400085, Maharashtra, India
[3] Telecom ParisTech, LTCI, 23 Ave Italie, F-75214 Paris 13, France