Experimental characterization of the separation between wavelength-multiplexed quantum and classical communication channels

Abstract

Quantum key distribution ͑QKD͒ is a new technique for secure key distribution based on the laws of physics rather than mathematical or algorithmic computational complexity used by current systems. Understanding the compatibility of QKD at 1310 nm with the existing commercial optical networks bearing classical wavelength-division-multiplexed ͑WDM͒ channels at 1550 nm is important to advance the deployment of QKD systems in such networks. The minimum wavelength separation for multiplexing QKD and WDM channels on a shared fiber is experimentally determined for impairment-free QKD+ WDM transmission.

Transmission of O-band wavelength-division-multiplexed heralded photons over a noise-corrupted optical fiber channel

“…For intra-city secure key distribution between trusted network nodes that are separated by distances shorter than 40 km [5], one can consider using the O-band (1260-1360 nm) instead for QKD [8][9][10][11][12][13]. This wavelength choice is attractive because the QKD channel and C-band Internet data channels are wavelength separated by > 170 nm, and so the noise condition at Oband becomes less severe [8,9]. It would be highly desirable if we could make QKD and Internet services coexist on the same fiber without having to impose any restrictions on the Internet services.…”

High-Rate Quantum Key Distribution with Superconducting Nanowire Single Photon Detectors

“…The high key rate achieved in these experiments permitted fast data collection, real-time optimization of the system parameters and straightforward clock recovery at 10.7 GHz without the need for atomic clocks or dedicated clock signals. The demonstrated combination of high key rate and relatively large link loss raises the possibility of adding additional opto-electronic components for networking or operating over existing spans between amplifiers at ~1300 nm wavelength [8].…”

Secure Quantum Communication Technologies and Systems: From Labs to Markets

“…Coexistence of a quantum channel in the 1300 nm band with four classical DWDM channels with an aggregate power of 2 dBm in the 1550 nm band was demonstrated for a system with a dark count level of 10 −3 photons/ns over 25 km of standard single mode fiber (SSMF) [50]. Another experiment [51] showed that at least 170 nm of separation are required between the QKD signal and a single 6 dBm conventional channel. System feasibility with a lower separation between quantum and classical channels was experimentally demonstrated with a CV-QKD system [52].…”