Saturday, September 21, 2019

On the verge of quantum supremacy again

July news:
Google expected to achieve quantum supremacy in 2019: Here’s what that means

Google‘s reportedly on the verge of demonstrating a quantum computer capable of feats no ordinary classical computer could perform. The term for this is quantum supremacy, and experts believe the Mountain View company could be mere months from achieving it. This may be the biggest scientific breakthrough for humanity since we figured out how to harness the power of fire. ...

Experts predict the advent of quantum supremacy – useful quantum computers – will herald revolutionary advances in nearly every scientific field. We’re talking breakthroughs in chemistry, astrophysics, medicine, security, communications and more. It may sound like a lot of hype, but these are the grounded predictions. Others think quantum computers will help scientists unlock some of the greater mysteries of the cosmos such as how the universe came to be and whether life exists outside of our own planet.
It seems as if I post these stories every year. Okay, here we go again.

I am betting Google will fail again. Check back on Dec. 31, 2019.

If Google delivers as promised, I will admit to being wrong. Otherwise, another year of phony promises will have passed.

Maybe already. The Financial Times is reporting:
Google claims to have reached quantum supremacy
The article is behind a paywall, so that's all I know. If true, you can be sure Google will be bragging in a major way. (Update: Read the FT article here.)

Update: LuMo tentatively believes it:
Google's quantum computing chip Bristlecone – that was introduced in March 2018 – has arguably done a calculation that took 3 minutes but it would take 10,000 years on the IBM's Summit, the top classical supercomputer as of today. I know nothing about the details of this calculation. I don't even know what amount of quantum error correction, if any, is used or has to be used for these first demonstrations of quantum supremacy.

If you have a qualified guess, let us know – because while I have taught quantum computing (in one or two of the lectures of QM) at Harvard, I don't really have practical experience with the implementation of the paradigm.

If true, and I tend to think it's true even though the claim is remarkable, we are entering the quantum computing epoch.
I look forward to the details being published. Commenter MD Cory suggests that I have been tricked.


  1. This is just a sales pitch to try and convince the public to dump more money into quantum computing when they have nothing they have already over promised to show for the billions already spent.

    If the damn thing had any actual usefulness to crack any encryption blah blah blah, do you really think the government and banking interests would say 'sure, plonk it down on the internet for anyone to tinker with'? If you do believe they would, I have a secret sciencey project of my own I'd like you to invest in, I call it "Making a billion dollars disappear into a MWI black hole".

  2. Roger, do you even know what they mean by supremacy? NISQs have no error correction and the sampling is on random circuits. It has nothing to do with proving that the underlying phenomena is really digital. In fact, "the same sampling complexity can be achieved from driven analog quantum processors, with less stringent requirements for coherence and control." ( We already know that QM is hard to compute. Hell, classical n-body problems are hard to compute, let alone quantum ones.

    You can find the article here:

    1. Aaronson: "It might or might not have any immediate use. If it doesn’t—well, the Wright Flyer also took years to find commercial applications. There’s obviously still a long, long way to go to get to fault-tolerance and scalability."

  3. Dear Roger,

    Here is a fascinating thread with lots of insights into this "Quantum Supremacy."

    "The article says:
    "A paper by Google’s researchers seen by the FT, that was briefly posted earlier this week on a Nasa website before being removed, claimed that their processor was able to perform a calculation in three minutes and 20 seconds that would take today’s most advanced classical computer, known as Summit, approximately 10,000 years."

    Why was that paper removed on the Nasa website? Also, I'm curious if supplementary data was provided to support the claims?"

    Also, I quote again: "Someone’s about to get a stern talking to on Monday it seems. I wonder though, if it was someone from NASA or from Google that made the mistake of uploading the paper earlier than they should have."

    Read it all here:

  4. See

  5. The Joshua Tree Quantum Computer Achieves Quantum Supremacy: Dr. Elliot McGucken's research group hath created a quantum computer capable of simulating over five sextillion atoms in the form of water molecules, performing massively complex calculations in a fraction of a second. These highly complex many-body calculations would take classical computers over a trillion trillion trillion years to solve and simulate. The JT Quantum Computer leverages the quantum multiverse to generate random numbers and pattern distributions via the entangled interactions of five sextillion atoms.

    Atoms in a drop of water = 3 atoms/molecule x 1.67 x 10^21 molecules = 5.01 x 10^21 atoms, or five sextillion atoms.

    The patent-pending Joshua Tree Quantum Computer works as follows:

    One obtains an eye-dropper and a glass of water.

    One takes up a drop of water in the eye-dropper.

    One drops said drop of water onto a flat piece of glass.

    Immediately one achieves and observes the random pattern distribution based on the entangled interactions between the over 5.01 x 10^21 atoms (five sextillion atoms), as the combined wave function collapses and the universe splits a trillion trillion times. Using a classical computer, one would be unable to simulate this calculation even after a trillion trillion trillions years. The JT Quantum Computer leverages the entangled quantum interactions between the atoms, thusly mining the Hilbert Space of parallel universes and the multiverse in a manner that is at least several sextillion times faster than IBM's leading SUMMIT super computer.

    And so the Joshua Tree Quantum Computer hath achieved quantum supremacy.

    The Wright Brother's first flight lasted under a minute, and already we have crossed far further than that, with big plans for the future, and multitudinous commercial applications. A new era hath dawned.

    We are currently seeking $200 million in funding to complete the design of the Redwood Quantum Computer, which will involve an entire bucket of water and which will be able to leverage the many worlds of Sean Carroll.

    dx4/dt=ic friends, dx4/dt=ic :) :) :)

    1. Yep, all kinds of "analog" reality is hard for classical computers but take a look at Martinis' paper on surface codes. Want to use Shor's algorithm to break RSA? Beauregard: "We introduce a circuit which uses 2n+3 qubits and O(n^3 lg(n)) elementary quantum gates in a depth of O(n^3) to implement the factorization algorithm." 2048*2+3 = 4099 cubits! Martinis: at an extremely optimistic 1/10th the threshold rate "[w]e can now estimate the number of physical qubits needed for our factoring problem. The 4,000 computational logical qubits require a total of about 4000 × 14,500 = 58 million physical qubits."