Quantum Computing, Quantum Interpretations, and Occam

Quantum Computing, Quantum Interpretations, and Occam

A recent worthwhile essay by Scott Aaronson Can Quantum Computing Reveal the True Meaning of Quantum Mechanics? explores the interplay between quantum computing and different quantum interpretations: http://www.pbs.org/wgbh/nova/blogs/physics/?p=2204. Scott is a leading expert on quantum computing and while he has an excellent regular blog here http://www.scottaaronson.com/blog/, I find I prefer his style of writing in this more recent popular piece. 

Scott digs into the Many Worlds Interpretation, the Copenhagen Interpretation, and Bohmian Mechanics - and explores their differences with regard to whether realising a working quantum computer would lend weight to one interpretation or another. The many other interpretations (https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics) are omitted for brevity. 

Above and beyond the proposed usefulness of quantum computers for simulating quantum physics and performing certain types of computations (e.g. factorisations) Scott believes that: The biggest application of quantum computers will be neither simulation nor codebreaking, but simply proving that this is possible at all! If you like, a useful quantum computer would be the most dramatic demonstration imaginable that our world really does need to be described by a gigantic amplitude wave, that there’s no way around that, no simpler classical reality behind the scenes. It would be the final nail in the coffin of the idea - which many of my colleagues still defend - that quantum mechanics, as currently understood, must be merely an approximation that works for a few particles at a time. 

I agree with the above quote from Scott and think it is the key takeaway from the article: the actual realisation of a useful quantum computer would be transformative not just in regards to technical capabilities but more so in relation to insights into our universe and reality. Of course, the negative, that of a useful quantum computer never being realised, would be just as interesting for the same reasons. 

Finally, when considering the details of quantum computations and the real consequences for the physical differences between the Many Worlds and Bohmian Mechanics interpretations Scott gives us an interesting trade-off with regards to Occam's Razor: 

* Bohmian Mechanics seems to imply more computational work than a quantum computer could simulate and indeed vastly more computation than could ever in principle be observed. Occam rules against unobservable computational processes. 

* Many Worlds of course seems to imply computation carried out across a near-infinite array of parallel unobserved universes. Occam rules against unobservable physical universes. 

[Supporters of both have standard responses to these criticisms.]

#quantum   #computing   #interpretations