Physics / mechanism
Quantum networks transmit quantum information between nodes using entanglement distribution and quantum state teleportation. The physical layer relies on photonic qubits—typically single photons at telecom wavelengths (1310 nm / 1550 nm)—propagating through optical fiber or free-space links. Key parameters: entanglement generation rate (current state-of-the-art: ~10 kHz over 50 km fiber), fidelity (>90% demonstrated in lab; <85% in deployed systems), and quantum memory coherence time (spin-photon interfaces in NV-diamond or rare-earth-doped crystals: microseconds to low milliseconds). Quantum repeaters remain the unsolved scaling problem—no deployed repeater exists yet. Point-to-point QKD links are commercially live (Toshiba, ID Quantique, QuantumCTek); multi-node entanglement networks are at prototype stage (QuTech Quantum Internet Alliance, AWS/Caltech).
Competitive landscape
Classical encrypted networks (TLS 1.3, post-quantum cryptography algorithms like CRYSTALS-Kyber/Dilithium) directly compete on the near-term security use case. PQC is software-deployable today at near-zero marginal cost—the primary competitive threat to QKD. Adjacent photonic approaches: continuous-variable QKD (cheaper detectors, lower fidelity), satellite QKD (Micius heritage; SpaceQT, SpeQtral). Quantum memory materials—rare-earth crystals, atomic ensembles, silicon-vacancy diamond—compete on coherence and integration. Integrated photonic chip platforms (SiPh, InP) are the component battlefield.
Companies using
Connected ideas
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Frontier (open questions)
- To be added.