The finite-key effects in quantum access networks are studied. We consider a quantum-classical network where each user is equipped with a certain wavelength to exchange secure keys, using quantum key distribution techniques, and another one to exchange classical data. Users are connected to the central office via a passive optical network. The quantum users are connected to the fiber links via an indoor wireless channel. We investigate the regimes of operation within which a secure key can be exchanged in a reasonable amount of time. We find out that by properly designing the system, it is possible to run both quantum and classical systems at their full capacity.

In this paper, low-complexity channel allocation methods are proposed for quantum access networks. We consider dense-wavelength-division-multiplexing passive optical network (DWDM-PON) structures that enable users to exchange secret keys, in addition to data transmission. We consider two main sources of noise in such systems, Raman scattering and fourwave mixing, and examine optimal channel allocation in different scenarios. We also take into account finite-key effects in the quantum key distribution (QKD) channels. Our numerical results show that the proposed wavelength assignment methods can significantly enhance the secret key generation rate of users.

This is a repository copy of Quantum and classical communications on shared infrastructure.