On 8/7/2019 11:15 AM, Philip Thrift wrote:
On Wednesday, August 7, 2019 at 1:03:44 PM UTC-5, Brent wrote: On 8/7/2019 1:08 AM, Philip Thrift wrote:On Tuesday, August 6, 2019 at 5:29:04 PM UTC-5, Brent wrote: On 8/6/2019 11:25 AM, Philip Thrift wrote:On Tuesday, August 6, 2019 at 1:00:23 PM UTC-5, Brent wrote: On 8/6/2019 6:38 AM, Bruno Marchal wrote:If the QC does its task effectively, the output basis qbits will be put into definite states,Relatively to the observer, but in the global state, the observer will inherit the superposition state, by linearity of the tensor products and of the evolution.In something like Shor's algorithm there is only one final state with non-vanishing probability. Yet this is the kind of algorithm that Deutsch cites as proving there must be many worlds. Brent That there is a multiplicity of /somethings/ https://en.wikipedia.org/wiki/Multiple_histories <https://en.wikipedia.org/wiki/Multiple_histories> is the basis for all semantics of quantum computing (by computer scientists) that I have ever seen.Same for classical computation...there are lots of states or functions. Did anyone think there had to be multiple worlds for the computer to work? Brent There is classical parallel hardware, e.g. made with multiple processors. Parallelism in quantum computers is achieved by parallel "worlds" or "paths": Quantum Path Computing - https://arxiv.org/abs/1709.00735 <https://arxiv.org/abs/1709.00735> Quantum circuit dynamics via path integrals: Is there a classical action for discrete-time paths? - https://iopscience.iop.org/article/10.1088/1367-2630/aa61ba <https://iopscience.iop.org/article/10.1088/1367-2630/aa61ba>But as you note with scare quotes, calling those "worlds" or "paths" is just metaphorical. They are not worlds you can visit or paths you can take. They are aspects of mathematical abstractions. BrentA “problem of time” in the multiplicative scheme for the n-site hopper Fay Dowker, Vojtˇech Havlicek, Cyprian Lewandowski, and Henry Wilkes - https://pdfs.semanticscholar.org/39d9/11e25b835ce8d34910c0a9e02f22ef8d4c41.pdf <https://pdfs.semanticscholar.org/39d9/11e25b835ce8d34910c0a9e02f22ef8d4c41.pdf> "Quantum Measure Theory (QMT*) is an approach to quantum mechanics, based on the path integral, in which quantum theory is conceived of as a generalized stochastic process." * https://pdfs.semanticscholar.org/bfda/1caa5afbbd9e2d6dcff5456325b60b64b909.pdf <https://pdfs.semanticscholar.org/bfda/1caa5afbbd9e2d6dcff5456325b60b64b909.pdf> The sum-over-histories formulation of quantum computing - https://arxiv.org/abs/quant-ph/0607151 <https://arxiv.org/abs/quant-ph/0607151> @philipthriftIf a multiplicity of somethings isn't present in a quantum computer, then how does the speedup occur?
By not decohering at every bit flip and keeping the single state rotating. Brent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/5e886399-3e62-575e-da96-7c77f4a0121e%40verizon.net.
