Experimental Demonstration of Datagram Switching With Monitoring in Quantum Wrapper Networks

Adapting the architecture and protocols of classical networks to quantum networking is challenging due to the quantum mechanical properties. In this article, we utilize a Quantum Wrapper Networking architecture that enables transparent and interoperable transportation of quantum wrapper (QW) datagrams, consisting of quantum payloads and classical headers, over optical fiber networks. We experimentally demonstrate end-to-end transportation of QW datagrams in a three-node packet-switched optical network testbed. The header and payload of a QW datagram are multiplexed in time and wavelength, i.e., the 1561.41 nm header precedes the L-band payload. A QW switch/router performs packet switching by reading the headers, generating new headers, and routing the datagrams to their destinations without disturbing quantum information in the payload. We use 20 km fiber links from the source to two distinct destinations in the testbed. Our experiments show
$>$
22 coincidence-to-accidental ratio (CAR) for both destinations at two different wavelength channels and clear visibility,
$>$
79%. We further investigate impairments such as chromatic dispersion and wavelength-dependent polarization rotations in the fiber. We observe that the classical headers' bit-error rate (BER) and the quantum payloads' CAR are correlated under the wavelength-independent channel attenuation. Thus, QW network control and management can utilize a type of performance monitoring. We also discuss the QW datagram design constraints and future fast packet switching implementations.