How many of your colleagues believe that a “real” quantum computer (i.e. one with enough qbits to allow it to solve problems that we can’t solve with a classical computer) will be a reality during our lifetime?

In news reports I see lots of optimism. But futuristic predictions have had a bad track record: many big predictions have not come to pass, while many of the things that did happen were not predicted.

If a news reporter simply looks at the track record of past predictions, shouldn’t the conclusion be despite what the people they interview tell them, the actual chance of a real quantum computer within our lifetime is very small?

]]>It is very hard to see how sharing memory strands as an explanation for entanglement would be consistent with Bell’s Theorem.

]]>**Job** wonders “What would the world be like if all operations were commutative?”

This question has a well-posed answer for classical dynamical systems, but its answer for quantum dynamical systems a “rough-water” and “messy” (per Steven Weinberg’s terminology of #38). The following points are excerpted from Gogolin, Muller, and Eisert’s “Absence of Thermalization in Nonintegrable Systems” (arXiv:1009.2493 [quant-ph], 2010).

“For \(n\) canonical degrees of freedom, one usually calls a system

integrableif there are \(n\) independent constants of motion with vanishing Poisson brackets.”

Note that in quantum dynamical systems, the criterion “vanishing Poisson brackets” implies “vanishing commutators” of the operators associated to constants-of-motion. The discussion of Gogolin *et al*. continues …

“In quantum mechanics, despite the common use of the term ‘integrable,’ the situation is much less clear, and different criteria are being applied in the literature. The most common notions of integrability are the following [list follows…]”

Further literature review along these thermodynamical lines will motivate *Shtetl Optimized* readers to survey, on the one hand, the fundamental research presented at QIP 2015 (don’t overlook the posters), and on the other hand, **the terrific series of YouTube videos that Schrödinger LLC provides**. See for example, the video descriptions of the quantum solver

Two well-referenced, accessible-to-students, review articles that are helpful (to me at least) in appreciating both sets of literature are Persi Diaconis’ “The Markov chain Monte Carlo revolution” (2009) and Christian Robert and George Casella’s “A short history of Markov Chain Monte Carlo: subjective recollections from incomplete data” (2011).

**Conclusion** The QIP 2015 lectures and posters, considered together with the surging simulation capabilities of enterprises like *Schrödinger LLC*, can be naturally appreciated — as it seems to me anyway — as establishing that a *third* “Markov chain Monte Carlo revolution” (as they have been called) is *already* underway … and this revolution is *already* generating a cornucopia of transformationally effective algorithms for unravelling quantum thermodynamical trajectories.

**Postscript** These references are provided in hope of motivating *Shtetl Optimized* readers to appreciate — and even comment publicly upon — the terrific materiel that *The Quantum Pontiffs* is providing with their QIP 2015 live-blogging.

For which outstanding service to the quantum community, this thanks and appreciation is extended to all four Pontiffs: Steve Flammia, Aram Harrow, Charlie Bennett, and Dave Bacon.

Good on `yah, Pontiffs!

—————-.

@article{citetag, Title = {The {M}arkov chain

{M}onte {C}arlo revolution}, Author = {Persi

Diaconis}, Journal = {Bulletin of the American

Mathematical Society}, Number = {2}, Pages =

{179--205}, Volume = {46}, Year = {2009}}

```
```

`@article{citetag, Title = {A short history of`

Markov Chain Monte Carlo: subjective

recollections from incomplete data}, Author

= {Christian Robert and George Casella},

Journal = {Statistical Science}, Number = {1},

Pages = {102--115}, Volume = {26}, Year =

{2011}}

What would the world be like if all operations were commutative?

]]>There is another theory which states that this has already happened. ]]>

QM is the proof that we’re living in the Matrix and that the machines had to save resources to fake the world:

– things have no clear state when you’re not looking at them.

– entanglement is clearly the equivalent of two threads sharing the same memory line in order to save RAM.

– randomness is a neat trick to procedurally generate “complex” state without the need for full history.

etc ]]>

Can you elaborate on why you choose (B)

i.e. QC’s will work but HHL will not?

]]>