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*From*: Henry Baker <hbaker1 AT pipeline.com>*Subject*: Re: [Cryptography] Quantum computers and the Government*Date*: Fri, 03 Sep 2021 12:50:27 +0000*Cc*: cryptography AT metzdowd.com*List-archive*: <https://www.metzdowd.com/pipermail/cryptography>*Reply-to*: hbaker1 AT pipeline.com*Sender*: "cryptography" <cryptography-bounces+ben=bentasker.co.uk AT metzdowd.com>*To*: "Phillip Hallam-Baker" <phill AT hallambaker.com>, John Levine <johnl AT iecc.com>

-----Original Message----- From: <hbaker1 AT pipeline.com> Sent: Sep 2, 2021 9:47 PM To: Phillip Hallam-Baker <phill AT hallambaker.com>, John Levine <johnl AT iecc.com> Cc: Cryptography Mailing List <cryptography AT metzdowd.com>, Henry Baker <hbaker1 AT pipeline.com> Subject: Re: [Cryptography] Quantum computers and the Government I have my own reservations about the current approaches to 'Quantum Computing', but they stem from real physics -- the 'Ahranov-Bohm Effect': https://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect Boiled down, it means that you can't build a 'quantum insulator', because a quantum device can 'sense' an electromagnetic potential, even when the electric and magnetic fields are identically zero. I.e., your quantum particle cannot be 'isolated' from its environment (except possibly within a black hole -- the subject of a long-standing debate over whether black holes can swallow information), so any entanglement will eventually be destroyed by external influences. This is why I think the current approaches to QC are QuixotiC. As a crude analogy, the 'digital revolution' of the 1940's enabled every active nonlinear device (e.g., transistor, vacuum tube triode) to be a 'thermodynamic refrigerator', whereby 'heat' (='noise') is rejected when the active device 'squares up' (normalizes) the digital signal, thus reducing the 'effective temperature' of the signal. The ' ' quotes are required because we're not measuring the Celsius temperature of the device, but the temperature of the isolated degrees of freedom involved in the computation. No refrigerator, no digital circuitry, because the errors accumulate too quickly (isn't this exactly the same problem for current qubits?). Current QC research may be focusing too much on Grover's algorithm, and haven't considered other valuable possibilities for quantum computation. This is why I mentioned quantum dots, which are the tip of an iceberg which will be revealed at sub nm feature sizes. When the digital electronic revolution happened, the analog engineers mostly didn't accept it, and now they're mostly dead. Planck's Principle: Science progresses one funeral at a time. https://en.wikipedia.org/wiki/Planck%27s_principle --- Oops, s/Grover's algorithm/Grover's and Shor's algorithms/g _______________________________________________ The cryptography mailing list cryptography AT metzdowd.com https://www.metzdowd.com/mailman/listinfo/cryptography

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