Experiments generate quantum entanglement over optical fibres across three real cities, marking progress towards networks that could have revolutionary applications.

Experiments generate quantum entanglement over optical fibres across three real cities, marking progress towards networks that could have revolutionary applications.

  • VindictiveJudge@lemmy.worldEnglish
    8·
    2 months ago

    Quantum entanglement communications also have fundamental problems that will likely render them effectively unusable. You need a key to decrypt anything you send, and the key has to travel no faster than c. It’s impossible to tell the data from the noise without the key. Attempting to read the data or to change the data being sent also collapses the effect, which can only be fixed by bringing the two systems together. In short, you can only send a single packet of data and you can’t use it without a key transmitted using traditional methods.

      • VindictiveJudge@lemmy.worldEnglish
        4·
        2 months ago

        The limit is c because you have to use cables, radio, or other traditional methods to send the key. The data in the entangled pair would also have to be set at the time the two devices are constructed, so that’s not super useful. It might be useful for single use authentication, but that’s about it.

        Don’t think of entanglement as being like one object in two spots. Think of it like identical twins. One twin getting a hair cut does nothing to the other twin’s hair. Similarly, altering a property of one entangled particle does nothing to the other and actually means they are no longer entangled or identical.