Quantum Wavelength-Division Multiplexing and Multiple-Access Communication Systems and Networks: Advanced Applications

A cost-effective global quantum Internet may be developed using the existing communication infrastructure. This article examines the quantum version of three conventional wavelength-division-multiplexing and multiple-access (WDM) communication systems and networks. They are Lambdanet-based broadcast WDM networks, quantum routers based on a waveguide grating router, and fiber-to-the-quantum nodes that are fed by two opposing and extreme quantum light signals, namely the coherent (Glauber) and number (Fock) states. Using the coherent states, we identify the classical behavior of the quantum WDM (QWDM) networks. Furthermore, employing quantum single-photon sources and exclusive quantum results, such as quantum correlations occurring in the receivers's states, are studied in these WDM communication systems and networks. Finally, we provide secure-key rate estimation for Lambdanet- and waveguide grating router (WGR)-based quantum key distribution networks leveraging the developed QWDM. As compared to Lambdanet, WGR obtains a higher rate of secure keys.