Single-End Adaptive Optics Compensation for Emulated Turbulence in a Bi-Directional 10-Mbit/s per Channel Free-Space Quantum Communication Link Using Orbital-Angular-Momentum Encoding
Cong Liu,
Kai Pang,
Zhe Zhao,
Peicheng Liao,
Runzhou Zhang,
Haoqian Song,
Yinwen Cao,
Jing Du,
Long Li,
Hao Song,
Yongxiong Ren,
Guodong Xie,
Yifan Zhao,
Jiapeng Zhao,
Seyed M. H. Rafsanjani,
Ari N. Willner,
Jeffrey H. Shapiro,
Robert W. Boyd,
Moshe Tur,
Alan E. Willner
Affiliations
Cong Liu
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA; Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
Kai Pang
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Zhe Zhao
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Peicheng Liao
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Runzhou Zhang
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Haoqian Song
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Yinwen Cao
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Jing Du
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Long Li
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Hao Song
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Yongxiong Ren
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Guodong Xie
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Yifan Zhao
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Jiapeng Zhao
The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
Seyed M. H. Rafsanjani
The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
Ari N. Willner
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Jeffrey H. Shapiro
Massachusetts Institute of Technology, Research Laboratory of Electronics, Cambridge, Massachusetts 02139, USA
Robert W. Boyd
The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
Moshe Tur
School of Electrical Engineering, Tel Aviv University, Ramat Aviv 69978, Israel
Alan E. Willner
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA
A single-end adaptive-optics (AO) module is experimentally demonstrated to mitigate the emulated atmospheric turbulence effects in a bi-directional quantum communication link, which employs orbital angular momentum (OAM) for data encoding. A classical Gaussian beam is used as a probe to detect the turbulence-induced wavefront distortion in the forward direction of the link. Based on the detected wavefront distortion, an AO system located on one end of the link is used to simultaneously compensate for the forward and backward channels. Specifically, with emulated turbulence and when the probe is turned on, the mode purity of photons carrying OAM l=1 is improved by ~ 21 % with AO mitigation. We also measured the performance when encoding data using OAM {l=-1,+2} and {l=-2,+1} in the forward and backward channels, respectively, at 10 Mbit/s per channel with one photon per pulse on average. For this case, we found that the AO system could reduce the turbulence effects increased quantum-symbol-error-rate (QSER) by ~ 76 % and ~ 74 %, for both channels in the uni-directional and bi-directional cases, respectively. Similar QSER improvement is observed for the opposite direction channels in the bi-directional case.
