  The great scientific and technological advances that are being carried out in
the field of quantum communications, accompanied by large investment programs
such as EuroQCI, are driving the deployment of quantum network throughout the
world. One of the final long-term objectives is to achieve the development of a
quantum internet that provides greater security in its services and new
functionalities that the current internet does not have. This article analyzes
the possible integration strategies of already deployed networks or in the
process of being deployed in order to reach a future global quantum network.
Two strategies based on the SDN paradigm are proposed, based on a hierarchical
controller scheme and on a distributed model. Each of these approaches shows
pros and cons and could be applicable in different use cases. To define these
strategies, the most relevant deployments of quantum communications networks
carried out to date has been analyzed, as well as the different approaches for
a quantum network architecture and topology, and the various proposed
definitions of what quantum internet is and what are the components that would
make it up in an ideal scenario. Finally, several detected opportunities and
challenges regarding security and technological aspects are presented.
