Optical Communication Systems

Optical Communication Systems refers to the devices used for communicating at a distance using light to carry information. A transmitter, which encodes a message into an optical signal, is used to carry the encoded message to the receiver.
Optical fiber is an example of said system. The transmitters are generally light-emitting diodes (LEDs) or lasers diodes. It transmits information by sending pulses of infrared light. The signal encoding is done by intensity modulation.

Optical Communication Systems such as Optical Fiber are most commonly used by telecommunications companies for internet connections, cable television and telephone signals transmitting.

  • Quantum processor for single photons

    Quantum processor for single photons | Illustration of the processes that take place during the logic gate operation: The photons (blue) successively impinge from the right onto the partially transparent mirror of a resonator which contains a single rubidium atom (symbolised by a red sphere with yellow electron orbitals). The atom in the resonator plays the role of a mediator which imparts a deterministic interaction between the two photons. The diagram in the background represents the entire gate protocol. Graphic: Stephan Welte, MPQ, Quantum Dynamics Division

    MPQ-scientists have realised a photon-photon logic gate via a deterministic interaction with a strongly coupled atom-resonator system.

    "Nothing is impossible!" In line with this motto, physicists from the Quantum Dynamics Division of Professor Gerhard Rempe (director at the Max Planck Institute of Quantum Optics) managed to realise a quantum logic gate in which two light quanta are the main actors. The difficulty of such an endeavour is that photons usually do not interact at all but pass each other undisturbed. This makes them ideal for the transmission of quantum information, but less suited for its processing. The scientists overcame this steep hurdle by bringing an ancillary third particle into play: a single atom trapped inside an optical resonator that takes on the role of a mediator. “The distinct feature of our gate implementation is that the interaction between the photons is deterministic”, explains Dr. Stephan Ritter. “This is essential for future, more complex applications like scalable quantum computers or global quantum networks.” (Nature, Advance Online Publication, 6 July 2016, DOI: 10.1038/nature18592).