# The Rise of Quantum Information and Communication Technologies
###### Abstract  
Today, we are already using several-component devices and systems based on the technologies developed during the first quantum revolution. Examples include microrhels for servers, laptops and smartphones, medical imaging devices, LED, lasers, etc. Now, a second quantum revolution is progressing fast, exploiting technological advances for the ability to engineer and manipulate other quantum phenomena such as superposition, entanglement and measurement. As a matter of fact, there is an impressive increase in research and development activities, innovation, public and private investments in a new wave of quantum services and applications. In this scenario, quantum information and communication technologies (QICTs) can be defined as a set of technological components, devices, systems and methods for elaborating, storing and transmitting/sharing quantum information. This paper addresses the challenges and opportunities enabling the rise of QICTs. In order to provide a concrete example, the paper describes an overview of the European project EQUO (European Quantum ecOsystems) dealing with ongoing innovation activities in the QICT avenue; in fact, EQUO aims at developing and demonstrating the feasibility of QKD (quantum key distribution) networks and their related integration in current telecommunications infrastructures towards the quantum internet. quantum information; quantum key distribution; quantum information and communication technologies +
Footnote †: journal: Quantum Reports  
an impressive increase in research and development activities, innovations efforts, public and private investments in new quantum services and applications (e.g., communications, computing, simulations, sensing and metrology) [1,2]. In this scenario, quantum information and communication technologies (QICTs) can be defined as a set of technological components, devices, systems and methods for elaborating, storing and transmitting/sharing quantum information. This paper focuses on QICT services and applications for quantum communications, specifically in the domain of quantum security, which appear to be more mature today as they rely on systems such as quantum key distribution (QKD) [3]. In particular, QKD is a secure communication method that implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only by them, which then can be used to encrypt and decrypt messages. The sender (traditionally referred to as Alice) and the receiver (referred to as Bob) are connected by a quantum communication channel that allows quantum states to be transmitted and an authenticated classical channel for deriving a common secret from the exchanged quantum information. QKD systems can be divided into two main classes: discrete-variable and continuous-variable. In the former class, the quantum information is typically encoded into discrete optical modes of a single photon, e.g., polarization or time bin; in this case, single-photon detectors are required for decoding. In the latter class, quantum states are described in an optical domain where the eigenstates are continuous with an infinite dimension, e.g., using Gaussian optical states. In order to provide another concrete example of QKD applications, the paper describes an overview of the European project EQUO (European Quantum eOSystems), dealing with ongoing innovation activities in the QICT avenue; in fact, EQUO aims at developing and demonstrating the feasibility of discrete-variable QKD networks and their related integration into current telecommunications infrastructures towards the quantum internet. In particular, the integration approach is based on the Software-Defined Networking (SDN) paradigm, where network programmability is enabled through logically centralized control, management and orchestration planes.