Quantum communication deals with absolutely secure transfer of classical messages by means of quantum cryptography or faithful transfer of unknown quantum states by means of quantum teleportation between distant sites. The essential element for quantum communication is to create remote entangled pairs of high fidelity. The main difficulty to create such a distant entangled pair is that both pho...

Quantum communication typically involves a linear chain of repeater stations, each capable of reliable local quantum computation and connected to their nearest neighbors by unreliable communication links. The communication rate of existing protocols is low as two-way classical communication is used. By using a surface code across the repeater chain and generating Bell pairs between neighboring ...

For any function f : X × Y → Z, we prove that Q(f) ·Q(f) · (logQ(f) + log |Z|) ≥ Ω(log |X |). Here, Q(f) denotes the bounded-error communication complexity of f using an entanglementassisted two-way qubit channel, and Q(f) denotes the number of quantum queries needed to determine x with high probability given oracle access to the function fx(y) def = f(x, y). We show that this tradeoff is close...

We present here a new approach to scalable quantum computing—a ‘qubus computer’—which realizes qubit measurement and quantum gates through interacting qubits with a quantum communication bus mode. The qubits could be ‘static’ matter qubits or ‘flying’ optical qubits, but the scheme we focus on here is particularly suited to matter qubits. There is no requirement for direct interaction between t...

In order to perform Quantum Cryptography procedures it is often essencial to ensure that the parties of the communication are authentic. Such task is accomplished by quantum authentication protocols which are distributed algorithms based on the intrinsic properties of Quantum Mechanics. The choice of an authentication protocol must consider that quantum states are very delicate and that the cha...

Nonlocality is at the heart of quantum information processing. In this paper we investigate the minimum amount of classical communication required in order to simulate a nonlocal quantum measurement. We derive general upper bounds, which in turn translate to systematic classical simulations of quantum communication protocols. As a concrete application, we prove that any quantum communication pr...

In the quantum teleportation scheme [1], quantum information of an unknown state of a d-level particle (an “input” particle) is faithfully transmitted from a sender (Alice) to a remote receiver (Bob) via an initially shared pair of maximally entangled particles. The distributed entangled particles shared by Alice and Bob function as a quantum information channel for the faithful transmission. Q...