back to article Japan starts work on global quantum crypto network

Japan is poised to start work on global quantum key distribution service and associated infrastructure. Toshiba today announced that Japan’s Ministry of Internal Affairs and Communications has named it the lead contractor on the project and that it aims to build a wide-area network that can accommodate over 100 quantum …

  1. Anonymous Coward
    Anonymous Coward

    All motion is the same

    Core claim:

    Electrons/photons etc. are not moving till you detect them, the act of measuring them 'sets' them to a new position. Ergo an attacker detecting a key exchange, destroys the key exchange by measuring it. Quantum cryptography depends on that claim.

    How would the electron or a photon know which interactions constitute 'measurement' and which don't. It is constantly interaction with everything around it, and it can never know which of those will result in a measurement being taken.

    So the core logic is faulty.

    And the claim of 'loophole' free proof is based on a black box, "Bell's test". A statistical test to separate random from related things.

    But there is a filter BEFORE the Bells test, and the filter causes the correlation that the Bells test is detecting. In some experiments the filter is a 'coincidence' circuit, in some experiments, its explicit filtering for other similar properties. In Quantum Key Exchange, the filtering is a signal sent separately.

    Your logic is broken, and your experiments have a big loophole in them, that you try to ignore: The filtering. You are not testing N experiments, you are selecting a subset of N for which the experiment holds true. In selecting that subset, you are creating the very correlation you are then detecting.

    1. Anonymous Coward
      Anonymous Coward

      Re: All motion is the same

      Everything is oscillating at near resonance. All forms of motion are components of this oscillating motion. All measurements are the net effect of (A): The thing observed on (B): the detector doing the observing.

      You already use this property with Red-Shift, relying on the connection between translational velocity of (B) and measure an apparent EM frequency of (A). So you already know these components are related forms of motion, at least in some branches of physics.

      Lets consider EM frequency as it approaches zero. The oscillation of light will approach the same resonance pattern of the detector. At perfect zero EM Hzs, the two things will be oscillating the same. The difference will approach zero. Because they're movement is the same way over the same field, one does not impart energy on the other. That's why zero EM hz has zero energy WITH RESPECT TO A GIVEN DETECTOR! That is why these properties are actually the net effect of (A) on (B) and why every measurement is with respect to the detector.

      Zero Electro magnetic hertz doesn't care about the motion of the detector here on planet earth, its zero WITH RESPECT TO THE OSCILLATION of matter in the detector. The earth can be moving at incredible speed but if the photon and detector are oscillating the same way, there is no energy imparted and zero HZ EM is zero energy. You see how you only could ever detect the relative motion of lights oscillation with respect to matter and never the actual oscillation of light?

      Do you see my point, it doesn't matter how the detector on earth is moving, Zero EM light must be in motion the same way as the detector in order not to impart any energy into it. Thus light as you measure it, is the *difference* between the detector and the photon. It is *not* the photon.


      Let the penny drop.

      You'll see how entanglement experiments are really proof that two photons moving the same way have all the same components of oscillation, if you filter for the difference due to detector. Perhaps you can even equalize the detectors too and eliminate the filtering. Suddenly it will all make sense.

      And you can look at your cloud chamber trails, see the ones going backwards in time, and realize its just an effect akin to rolling shutter effects, or spokes on wheel going backward on film: the net effect of two oscillations.

      You'll suddenly understand where matter gets its scale from, why the speed of light appears to be a constant, why matter and space appears uniform in all directions.

  2. Anonymous Coward

    In reply to the Anonymous Cowards

    I am not an expert in quantum cryptography but as far as I know neither are you two.

    In any case, building a test setup (100 devices and 10000 users) seems like a great way to test for your possible loopholes and for its practicality.

    I, for one, hope it's successful. A pint to the Brit boffins working on this. And a Sapporo for the Japanese as well.

  3. YetAnotherJoeBlow


    What I do not know of quantum cryptography could fill a book - but I do know it must be secure because I know several groups trying diligently to subvert it. My question is can an old dog learn new tricks as it looks fascinating. I am reasonbly certain my math will hold.

    1. amanfromMars 1 Silver badge

      Re: QC Low Blows for Old Lags Chasing New Dogs

      Would those several groups trying diligently to subvert it be fundamental terrorists, YetAnotherJoeBlow?

      Join them at your peril is good sound advice methinks.

    2. amanfromMars 1 Silver badge

      Re: QC

      A Question to both Ponder and Wonder at, or Investigate and Implausibly Deny, is do any Red Teams have Cleanskins in the Game with/for C42 Quantum Communication Control Systems ...... AI@ITsWork .... Exercising and Experimenting with Creative Command and Control of CyberSpace with Communicative Computers ……. AI @ ITs Work with Novel and Noble CyberIntelAIgent Security Protocols?

      And yes ..... one would have to admit, well he would say that, wouldn't he? ..... because it is no Top Secret, is it?

  4. Geralds-for-himself

    Trusted and entrusted nodes for QKD

    There was an research paper in Nature using a satellite as an untrusted node in quantum key distribution. This has been demonstrated. While it's only 2 trusted nodes in the paper it's easy to see how it can be expanded.

    Yin, J., Li, Y., Liao, S. et al. Entanglement-based secure quantum cryptography over 1,120 kilometres. Nature 582, 501–505 (2020).

    1. amanfromMars 1 Silver badge

      Re: Trusted and entrusted nodes for QKD

      There was an research paper in Nature using a satellite as an untrusted node in quantum key distribution. This has been demonstrated. While it's only 2 trusted nodes in the paper it's easy to see how it can be expanded. ... Geralds-for-himself

      Now that is what anyone with a fervent interest in the field would call a Great Game Changer, Geralds-for-himself.

      And geopolitically, such puts the Far East and specifically China way out in front and enabled to be able to be leading the West in any directions entangling Great Game Changers would choose to explore, experience and experiment in. ‽

      Bravo, China. What now is your pleasure to treasure and enjoy?

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