While the commercial deployment of 5G networks and beyond is a reality, first work for definition study 6G has started. The scientific community agrees that these will be characterised by very high spatial density access points, heterogeneity technologies, an increased number users per point, demand ubiquitous connectivity must combine ultra-low latency, bandwidth, energy efficiency [1, 2]. Amo...

In the 1980s it was first realized that quantum–mechanical phenomena can be exploited directly for the manipulation, storage and transmission of information. The discovery of quantum algorithms for prime factorization [18] and unstructured search [7], which outperformed the best classical algorithms for these tasks significantly, opened up new vistas for computer science and gave an initial thr...

Single electron spins in quantum dots are attractive for quantum communication because of their expected long coherence times. We propose a method to create entanglement between two remote spins based on the coincident detection of two photons emitted by the dots. Local nodes of two or more qubits can be realized using the dipole-dipole interaction between trions in neighboring dots and spectra...

We report an experimental demonstration of a bit-flip error-rejection protocol for error-reduced transfer of quantum information through a noisy quantum channel. In the experiment, an unknown state to be transmitted is encoded into a two-photon entangled state, which is then sent through an engineered noisy quantum channel. At the final stage, the unknown state is decoded by a parity measuremen...

We review recent theoretical proposals for implementation of quantum computing and quantum communication with atoms. The first example deals with the realization of a universal quantum simulator with atoms and ions. The second example outlines the implementation of a quantum repeater with atomic ensembles.

We show an eavesdropping scheme on Boström-Felbinger communication protocol ( called pingpong protocol ) [Phys. Rev. Lett. 89, 187902 (2002)] in an ideal quantum channel. A measurement attack can be perfectly used to eavesdrop Alice’s information instead of a most general quantum operation attack. In a noisy quantum channel, the direct communication is forbidden. We present a quantum key distri...

Quantum theory is, in some way, “non-classical.” For instance, the behavior of entangled systems (i.e., shared quantum information) under measurements cannot, in general, be explained by shared classical information. With classical communication, on the other hand, both the correlations entanglement leads to as well as quantum channels can be reproduced in principle. Here, crucial questions are...

The long-standing problem of quantum information processing is to remove the classical channel from quantum communication. Introducing a new information processing technique, it is discussed that both insecure and secure quantum communications are possible without the requirement of classical channel. Quantum cryptography [1-7] and teleportation [8] are the two important aspects of quantum comm...

The communication complexity of a quantum channel is the minimal amount of classical communication required for classically simulating a process of state preparation, transmission through the channel and subsequent measurement. It establishes a limit on the power of quantum communication in terms of classical resources. We show that classical simulations employing a finite amount of communicati...