Abstract
In a quantum network involving multiple communicating parties, an important goal is to establish high-quality pairwise entanglement among the users without introducing multiple entangled-photon sources which would necessarily complicate the overall network setup. Moreover, it is preferable that the pairwise entanglement of photons is in the time-bin degree of freedom as the photonic time-bin qubit is ideally suited for fiber-optic distribution. Here, we report an experimental demonstration of a field-deployable quantum communication network involving multiple users, all of whom share pairwise entanglement in the time-bin degree of freedom of photons. In particular, by utilizing a single spontaneous-parametric down-conversion source which produces a broadband pair of photons and the wavelength-division demultiplexing/multiplexing technology, all the communicating parties within the network are always simultaneously ready for quantum communication. To further demonstrate the practical feasibility of a quantum network with time-bin entanglement over a wavelength-multiplexed fiber network, we demonstrate entangled-photon quantum key distribution with three users, each separated by 60 km of optical fibers.
Highlights
One of the principal goals in quantum communication is to distribute photonic entanglement to distant parties, thereby establishing a quantum channel, to enable implementations of certain entanglement-based communication protocols that are not possible classically, e.g., quantum teleportation,1–5 quantum key distribution (QKD),6–9 dense coding,10–12 and quantum secret sharing.13–15 In recent years, tremendous technical achievements toward long-distance quantum communication have been reported via free-space16,17 and via optical fiber links.18,19 it remains to be a formidable problem to expand quantum communication to include multiple communicating parties, i.e., to build a quantum network, as it requires overcoming many fundamental and technical challenges
The fiber optic quantum network is based on a single entangled-photon source which distributes a pair of time-bin entangled qubits to scitation.org/journal/app any two members of the quantum network, and through the use of the wavelength-division demultiplexing/multiplexing technology, all the network members are simultaneously ready for quantum communication
The fact that each network member does not have to be equipped with its own entangled-photon source greatly reduces the complexity and the cost of the network setup
Summary
One of the principal goals in quantum communication is to distribute photonic entanglement to distant parties, thereby establishing a quantum channel, to enable implementations of certain entanglement-based communication protocols that are not possible classically, e.g., quantum teleportation, quantum key distribution (QKD), dense coding, and quantum secret sharing. In recent years, tremendous technical achievements toward long-distance quantum communication have been reported via free-space and via optical fiber links. it remains to be a formidable problem to expand quantum communication to include multiple communicating parties, i.e., to build a quantum network, as it requires overcoming many fundamental and technical challenges. Given the importance of the quantum network in quantum information technology, a number of interesting ideas and technical achievements toward the quantum network have been reported, including the quantum repeater, quantum memory, generalized quantum measurement, qudit entanglement, hyper-entanglement, trusted nodes, active-switching, wavelength-division multiplexing (WDM), wavelength selective switch, decoy state QKD, and twin-field QKD.. Given the importance of the quantum network in quantum information technology, a number of interesting ideas and technical achievements toward the quantum network have been reported, including the quantum repeater, quantum memory, generalized quantum measurement, qudit entanglement, hyper-entanglement, trusted nodes, active-switching, wavelength-division multiplexing (WDM), wavelength selective switch, decoy state QKD, and twin-field QKD.58–61 While these developments certainly constitute important building blocks toward the global quantum network, a full-fledged quantum network is likely to be years away from fruition. To further demonstrate the practical feasibility of a quantum network with entangled time-bin qubits over a wavelength-multiplexed fiber network, we demonstrate entangled-photon quantum key distribution with three users, each separated by 60 km of optical fibers
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