One-way invisible cloak using parity-time symmetric transformation optics Zhu, Xuefeng ; Feng, Liang ; Zhang, Peng ; Yin, Xiaobo ; Zhang, Xiang Abstract Publication: Optics Letters Pub Date: August 2013 DOI: 10.1364/OL.38.002821 Bibcode: 2013OptL...38.2821Z