NYTimes.com: Quantum Computing Inches Closer to Reality After Another Google Breakthrough

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John Clark

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Dec 10, 2024, 1:52:45 PM12/10/24
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Explore this gift article from The New York Times. You can read it for free without a subscription.

Quantum Computing Inches Closer to Reality After Another Google Breakthrough

Google unveiled an experimental machine capable of tasks that a traditional supercomputer could not master in 10 septillion years. (That’s older than the universe.)

https://www.nytimes.com/2024/12/09/technology/google-quantum-computing.html?unlocked_article_code=1.gU4.HQ6B.CrWBbQsS0o0t&smid=em-share

PGC

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Dec 12, 2024, 4:17:26 PM12/12/24
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From Neven's blog, who thinks Quantum Computing supports MWI indirectly: https://blog.google/technology/research/google-willow-quantum-chip/ 

The key argument linking Google's results to MWI is this: Quantum error correction assumes the universal applicability of unitary evolution, the cornerstone of quantum mechanics under MWI.The increasing fidelity of error correction as systems scale, suggests that quantum effects persist robustly, even in larger, more complex systems. This bolsters the plausibility that the universe operates as a fully quantum system without invoking wavefunction collapse. If the multiverse exists as described by MWI, then the success of large-scale quantum computing is a natural consequence, as each computation's branching outcomes correspond to the different branches of the multiverse.

The argument is indirect and circumstantial but noteworthy. While it does not "prove" MWI, it aligns with MWI's predictions, making the interpretation not as implausible as many make it out to be.

In collapse interpretations, decoherence explains why superpositions appear to "choose" classical outcomes. Quantum error correction could still function as long as the system avoids collapse during computation and decoherence is managed. The coherence between qubits would then represent potential states rather than actual branches. Probabilistic Framework Collapse interpretations could argue that error correction succeeds because the physical system probabilistically maintains coherence during operations. Measurement is avoided until after computation, so the qubits remain in their superposed states (potentially explained as amplitudes of possibility rather than branches of reality).

Copenhagen might require ad hoc explanations to justify why quantum error correction apparently aligns with the formalism of the wavefunction, even when interpreted as merely a tool for probabilistic prediction rather than a real, branching entity. Error correction often operates automatically, with no human observer collapsing the system. Collapse interpretations would have to clarify how coherence is maintained and errors are corrected without invoking an observer.

It appears more straightforward with MWI (Warning: I am not MWI proponent/advocate): The redundancy encoded in error correction exists across all branches, with amplitudes adjusted to represent error-free computations. No "collapse" mechanism is required; the wavefunction evolves deterministically according to Schrödinger's equation. The observed outcomes (error-free computations) are a result of constructive interference within the multiverse. As quantum computers like Google's Willow chip demonstrate increasing coherence and error correction efficacy, they indirectly support interpretations like MWI that treat the wavefunction as real and universal. This support comes not as convincing/direct proof of MWI but through Occam: MWI requires fewer additional assumptions than collapse theories to account for the observed success of quantum error correction.

Cosmin Visan

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Dec 12, 2024, 5:05:32 PM12/12/24
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That's the same breakthrough like that one from 20 years ago ?

John Clark

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Dec 12, 2024, 8:19:15 PM12/12/24
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On Thu, Dec 12, 2024 at 11:17 AM PGC <multipl...@gmail.com> wrote:
From Neven's blog, who thinks Quantum Computing supports MWI indirectly: https://blog.google/technology/research/google-willow-quantum-chip/  
     > The key argument linking Google's results to MWI is this: Quantum error correction assumes the universal applicability of unitary evolution, the cornerstone of quantum mechanics under MWI.The increasing fidelity of error correction as systems scale, suggests that quantum effects persist robustly, even in larger, more complex systems. This bolsters the plausibility that the universe operates as a fully quantum system without invoking wavefunction collapse. If the multiverse exists as described by MWI, then the success of large-scale quantum computing is a natural consequence, as each computation's branching outcomes correspond to the different branches of the multiverse. [ ...] Copenhagen might require ad hoc explanations to justify why quantum error correction apparently aligns with the formalism of the wavefunctionIt appears more straightforward with MWI (Warning: I am not MWI proponent/advocate): The redundancy encoded in error correction exists across all branches, with amplitudes adjusted to represent error-free computations.  No "collapse" mechanism is required; the wavefunction evolves deterministically according to Schrödinger's equation. [...] This support comes not as convincing/direct proof of MWI but through Occam: MWI requires fewer additional assumptions than collapse theories to account for the observed success of quantum error correction.
 
If Quantum Computers ever become practical, and is looking increasingly likely that they will, among those whose job it is to write programs for those machines, Many Worlds is likely to become much more popular than its rivals because to write computer code with efficiency it's necessary to form a mental picture about what's going on and, because of Occam, it's much easier to do that with Many Worlds than with Copenhagen or Pilot Wave. And textbooks about how to write code for Quantum Computers are likely going to take that approach also, which will greatly influence the next generation of physicists; unless of course AI turns out to be the one that writes all the code. 

 John K Clark    See what's on my new list at  Extropolis
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