Kvantumfotonikai

Kvantumfotonikai is the field that studies and applies quantum phenomena of light to information processing, communication, sensing and metrology. It combines principles from quantum optics, photonics and information science to generate, manipulate and detect quantum states of light such as single photons, entangled photon pairs and squeezed states. The goal is to realize tasks that surpass classical capabilities, using photons as carriers of quantum information.

Key technologies include sources based on spontaneous parametric down-conversion and quantum dots for producing single photons or entangled pairs, and detectors such as superconducting nanowire single-photon detectors and single-photon avalanche diodes. Photonic circuits, including beam splitters, phase shifters and interferometers, enable on-chip manipulation of quantum states, often in integrated platforms that operate at telecom wavelengths to align with optical fiber networks.

Major applications span secure communication, exemplified by quantum key distribution, as well as quantum computing with linear optics, quantum simulation and quantum-enhanced sensing. Quantum networks aim to distribute entanglement over long distances, using repeaters and memories to enable scalable communication and distributed quantum processing.

Challenges in kvantumfotonikai include optical losses, decoherence of quantum states, imperfections in sources and detectors, and the difficulty of scaling integrated photonic systems while maintaining high fidelity. Room-temperature operation is often challenging, leading to reliance on specialized materials and cryogenic components for certain technologies.

The field continues to evolve toward more robust, scalable photonic qubits, hybrid systems that combine photons with matter-based qubits, and broader adoption of communication-band devices to bridge laboratory experiments and real-world quantum networks.