1. CNR-SPIN Salerno, via Giovanni Paolo II n. 132, Fisciano 84084, Italy
2. Physics Department, University of Salerno, via Giovanni Paolo II n. 132, Fisciano 84084, Italy
3. Department of Physical and Chemical Science, University of L’Aquila, and CNR-SPIN L’Aquila, via Vetoio, L’Aquila 67100, Coppito, Italy
4. Department of Energy Science, Sungkyunkwan University, Suwon 16419, Korea
5. Istituto Nazionale di Ricerca Metrologica, INRIM—Strada delle Cacce, Torino 10135, Italy