Slashdot Mirror

← Back to Stories (view on slashdot.org)

Quantum Cryptography Slowed by "Dead Times"

Posted by CmdrTaco on from the what-i-call-the-time-before-my-first-cup-of-coffee dept.

coondoggie writes "Researchers at the National Institute of Standards and Technology and the Joint Quantum Institute said today that technological and security issues will stall maximum transmission rates at levels comparable to that of a single broadband connection, such as a cable modem, unless researchers reduce "dead times" in the detectors that receive quantum-encrypted messages."

5 of 75 comments (clear)

  1. I have no clue what this is about by Wannabe+Code+Monkey · · Score: 4, Insightful

    I read the summary and didn't understand a single part of it, but it sounded interesting and I though, "The article must explain things better." But after reading the article I still have no idea what is going on. Is there someone else that could maybe help explain what this story is all about?

    --
    We always knew Comcast was corrupt, here's the proof: http://tech.slashdot.org/comments.pl?sid=1909890&cid=34545432
    1. Re:I have no clue what this is about by Anonymous Coward · · Score: 5, Funny

      hardware which may or may not exist yet is going to run slowly unless said hardware is improved at some time in the future when it may or may not exist.

  2. meta by TheSHAD0W · · Score: 4, Insightful

    So use the quantum cryptography to exchange a large classic private key.

  3. Organization often confussed with... by Nezer · · Score: 4, Funny

    It should be noted that the Joint Quantum Institute does *entirely different* research than the Quantum Joint Institute located in Amsterdam.

  4. Dead time in scientific instruments by confused_demon · · Score: 5, Informative
    I've got some clue what's meant by dead time for scientific measurements. Basically, dead time is the amount of time after an event is measured that it takes for the detector system to reset. For example, if you're using a Spectroscopy Amplifier (or another shaping amplifier) dead time comes from two signals coming too close to each other. Shaping amplviers are setup so that a square wave (or a step) would produce a characteristic shape (usually a flat-topped Gaussian shape, or a trapazoid). The purpose of the shaping is to allow for the imperfections in detector to be integrated into a single measurement which is easier to process (signal being generated slowly or slowly getting through prior parts of the circuit). If a second signal occurs while the shaping is still taking place it will be integrated into the output of the shaping amplifier resulting in a garbled output for both inputs.

    The net result is that as you send more and more signals to a spectroscopy system, the dead time increases and eventually you get no output because the electronics are constantly saturated. A well put together system will include a measurement of dead time so you know how many signals you're loosing.