Quantum Bayesian Networks

April 21, 2020

Martinis Resigns from The Google

Filed under: Uncategorized — rrtucci @ 7:56 am

Quantum Supremacy (the movie)

Quantum Supremacy (the movie)

6 years ago, I wrote the above satirical article about Hartmut Neven, the head of Google’s quantum AI lab . Today, Martinis, the main inventor of that lab, resigned. I don’t see how Google’s quantum computing hardware program can continue without Martinis. Neven may be close to the janitorial fate that my movie predicted, back in the year 2040.

April 18, 2020

Google’s Quantum Stallion

Filed under: Uncategorized — rrtucci @ 3:56 pm

A recent thread in Reddit gave links to 4 talks available on YouTube about Google’s Sycamore quantum computer. My comment in that thread has received a very negative rating. Reddit readership has such poor taste! Here is my comment:

All 4 speakers are girlie men. Bring back Hartmut Neven. At least he’s a handsome stud of a man. What a hunk! Google’s Quantum Stallion.

April 17, 2020

Today, I squashed a very old bug in my program “Entanglish” for calculating Squashed Entanglement

Filed under: Uncategorized — rrtucci @ 7:02 am

A small cause for joy for me in these otherwise sad and depressing Covid-19 times.

For personal reasons, for a long while, I had put any serious development of Entanglish on the back burner. However, yesterday, I decided to look at it again. Entanglish has had a big, nasty bug since it was created. I was aware of the bug all along, and have been warning Entanglish’s users about it.

The bug was in the recursion formula for calculating squashed entanglement (aka CMI entanglement) E. It took me until now to find a **numerically stable** recursion formula for calculating E(n+1) from E(n) for n=0, 1, 2, … The Calculus of Variations gives some strong constraints on what the form of that recursion formula should be, but it allows for some leeway in the exact form. Some forms are numerically stable and others aren’t. It’s a tricky recursion formula because it requires taking the exponential of a matrix, something that in a recursion formula, can, if one chooses a numerical unstable method to do this, cause errors in numerical precision to grow exponentially at each step, sort of what happens in Chaos Theory.

Anyhow, the bottom line is that, after a lot of experimentation, I think I have finally found a numerically stable recursion formula that satisfies all the constraints, and only those constraints (no additional ones), mandated by the Calculus of Variations.

April 11, 2020

My new website and business model

Filed under: Uncategorized — rrtucci @ 7:31 am

For the past year, I’ve been mulling over my future, especially as it pertains to quantum computing. Finally, in the last few days, I believe that I have finally converged to a local minimum. Yes, I know, I am a very slowly converging series. But I do converge eventually. Lo and behold, today I find that I have converged close to where I started my journey 20 years ago. So, I must have been travelling in circles all that time! 20 years ago, I started Artiste as a small, optimistic, but not overly ambitious, software company with the website http://www.ar-tiste.com . Today, I am restarting Artiste, again as a small, optimistic, but not overly ambitious (or VC dominated like most qc startups), software company. To mark the occasion, I’ve started a new website. Please check it out if you like my previous work and you think you’d like to hire us/me to write classical or quantum bayesian network software for you:





April 10, 2020

Using z2jk to teach a quantum computing course or to create your own quantum cloud

Filed under: Uncategorized — rrtucci @ 11:57 pm


About 4 months ago, I wrote for this blog an article entitled “List of Quantum Clouds“. In that article, I listed 17 “quantum clouds”. By now, there are probably a few more. The “HWB” (hardware backed) quantum clouds of Dwave, Rigetti and IBM, offer access to already existing, on-line qc hardware. I’ll call all the other quantum clouds “proxy” quantum clouds. Proxy quantum clouds can run a quantum circuit on a cloud hosted simulator or they can relay that quantum circuit to a HWB quantum cloud. Out of all the proxy quantum clouds, two of them are backed by two hungry, cruel giants called Amazon and Microsoft. The rest are backed by ants.

Will proxy quantum clouds, including the ones run by the 2 cruel giants, ever become popular or profitable? It remains to be seen.

Proxy quantum clouds are certainly not a guaranteed slam dunk from a business perspective. Users might decide to simulate their quantum circuits more cheaply by running them on their own PCs. And, if users want to run their quantum circuits on real qc hardware, they might choose to eliminate the proxy, and send their quantum circuits directly to a HWB quantum cloud. Users might eliminate the proxy middleman because it is slowing things down and charging the users a toll fee to do so.

Another important reason why proxy quantum clouds may fail, is open source software such as z2jk (Zero to Jupyterhub with Kubernetes). z2jk is free, open source software that allows anyone, even someone with almost zero understanding of the underlying docker/kuberbetes technology, to set up their own jupyterhub cloud service in minutes.

A jupyterhub, in case you are not familiar with the term, is software that can ‘spawn’ for many users, a personal file system in the browser of each user. This personal file system can open, run and save on the cloud many jupyter notebooks. So far, all quantum clouds are, deep down, jupyterhubs.

z2jk is superbly well documented and maintained by UC Berkeley, where it is used to teach many courses. Furthermore, z2jk is very sophisticated. It uses the latest in Jupyter notebook and cloud technology (Docker containers and container orchestration via Kubernetes). Due to Kubernetes, z2jk can be run on anything from a single workstation to multiple cloud providers running concurrently (cloud providers such as Amazon AWS, Microsoft Azure, Google cloud, Digital Ocean, IBM cloud, etc.).  Kubernetes magically and seamlessly balances the load among all servers.  z2jk is also very flexible: it can be used to teach any data science or quantum computing course, or you can use it to set up your own jupyterhub quantum cloud service, only for yourself, or for you and a group of your peers.

z2jk is so good that it may single-handedly put the kibosh on all proxy quantum clouds. Goodbye Amazon and Microsoft quantum clouds. Goodbye proxy quantum clouds run by startups. We hardly knew ye.

April 8, 2020

Quantum Natural Language Processing and the fake orgasm scene from the film “When Harry Met Sally”

Filed under: Uncategorized — rrtucci @ 6:51 pm

Check out the following article:

Quantum Natural Language Processing” by a staff member of CQC (Cambridge Quantum Con, aka Cambridge Quantum Computing)

Someone started a thread about this article in Reddit. In that thread, someone named Anasoori commented

“Language is quantum native”

Yes yes yes

To this marvelously descriptive comment, I replied merely with a YouTube link:

I also replied more explicitly and extensively with the following comment:

“Language is quantum mechanics native”

Words in a sentence are in a quantum superposition?

You will notice that the proponents of this “theory” do not try to prove or disprove their “theory” with any data. That is because this “theory” does not predict anything about Nature that can be verified in the lab and that is not in the “theory” a priori. Or if it does, the authors are not interested in comparing those predictions with data because that would be highly embarrassing to them.

Once more, Cambridge Quantum Computing proves that it’s a startup headed and staffed by crackpots and con artists. It is also probably a criminal enterprise that is being funded by a Chilean fugitive of the law, Alberto Chang Rajii, who is accused of stealing hundreds of millions of dollars through a Ponzi scheme.

Notice that Cambridge Quantum Computing does not publicly disclose where it got its funding


It is not hard to guess what is the main source of that funding:


April 1, 2020

Yet Another Optimized Compiler (Yet AOC)

Filed under: Uncategorized — rrtucci @ 11:18 pm


Qubiter Logo

(Bad Pun and political advertisement: AOC also means Alexandria Ocasio Cortez, one of my heroes. My father was Italo-American and my mother was Puertorrican. I lived in Puerto Rico until the end of high-school (Colegio San Ignacio de Loyola, Hurray!), at which point I went to college (MIT, Hurray!) and have been in the US ever since. As a liberal Democrat from PR, I am very proud to be ethnically and spiritually related to AOC.)

Check out the following paper unveiled last night in ArXiv:

An Open-Source, Industrial-Strength Optimizing Compiler for Quantum Programs, by Robert S. Smith, Eric C. Peterson, Mark G. Skilbeck, Erik J. Davis, https://arxiv.org/abs/2003.13961

This is an exciting development for me since I have been a proponent and practitioner of the art of quantum compilers for a long time.

The new “optimized quantum compiler” by Rigetti is a computer program that tackles the problem of searching for the “shortest” quantum circuit. Note, however, that it comes with some caveats:

  1. This program doesn’t generally find the optimal solution to this problem. Finding the optimal solution for this problem most probably requires an exp(number of qubits) number of operations to “finish”. So for more than 5 to 10 qubits, an optimal program for this problem would be so slow that it would be well-nigh useless. The shortest circuit problem probably has many local minima. This program is not even guaranteed to find one of those local minima. It finds something that is optimal only within small segments of the circuit. “piecewise optimal”?
  2. What is the “shortest circuit” is somewhat debatable and device dependent. The output of this computer program is device dependent, as it favors gates that are native to the Rigetti qc.
  3. This program is written in Lisp, which is, to put it mildly, not one of the most popular or fastest-growing or newest or easiest to write, computer languages in town.

To be fair, IBM’s optimizing quantum compiler suffers from all the same difficulties, except that theirs is written in Python/C++ instead of Lisp. Microsoft’s quantum compiler suffers from these difficulties too, but theirs is written in one or more of Microsoft’s dead or dying languages C#, F#, Q#. (The # stands for a tombstone with a cross.) In fact, classical compilers suffer from similar difficulties too.

(IBM is very pseudo-original, as is their wont with Qiskit, and calls theirs a transpiler instead of a compiler, but dozens of researchers that have preceded IBM in this field call this type of software a compiler.)

Quantum compilers have a long history. Nowadays, Microsoft, IBM, Rigetti and Google, have one. Even the hoax company Cambridge Quantum Computing (CQC) has an awful piece of not-open-source software called t|ket> that they refer to ostentatiously as a “quantum compiler”.

The first paper to use the term “quantum compiler” in its title (and probably also in its body but I’m less sure about that) was mine

A Rudimentary Quantum Compiler, by Robert R. Tucci, https://arxiv.org/abs/quant-ph/9805015

I quickly followed that paper with a beefier “second edition” with more “quantum compiler optimizations”:

A Rudimentary Quantum Compiler(2cnd Ed.), by Robert R. Tucci, https://arxiv.org/abs/quant-ph/9902062

Within a year of my “rudimentary quantum compiler” paper, I wrote a C++ program called Qubiter that implemented the algorithms of the paper, and I filed for a patent for Qubiter (It’s item #2 in this list. The patent expires today, April 01, 2020). Later, I also applied for an ARO (Army Research Office) grant to enhance Qubiter. I applied for the grant jointly with a university professor that specializes in Linear Algebra. Sadly, the application was rejected. (That’s an interesting story in itself, but for another time.)

My original reason for studying quantum compiling was to “compile” the nodes of a quantum Bayesian network (i.e., to replace each of the nodes by a sequence of elementary gates). In fact, I wrote a paper explaining how to achieve that goal

How to Compile A Quantum Bayesian Net, by Robert R. Tucci, https://arxiv.org/abs/quant-ph/9805016

More recently, I wrote an open-source quantum simulator in Python, that I also called Qubiter. The new Qubiter includes a Python implementation of the old C++ Qubiter. It also includes, in a folder called LEGACY, the C++ code for the original Qubiter.

My original use of the word “quantum compiler” has been expanded somewhat by others throughout the years. To be more specific, nowadays I call Qubiter’s original quantum compiler a “quantum CSD compiler”. CSD stands for Cosine-Sine Decomposition, a very famous, in its own right, decomposition in Linear Algebra. Here is the LAPACK implementation of CSD. My “rudimentary quantum compiler” paper was the first paper ever to use that decomposition to compile an arbitrary unitary matrix (i.e., to decompose it into a sequence of elementary gates such as single qubit rotations and CNOTs).

Since I wrote my original paper on quantum compilers, I’ve written several other arxiv papers on the subject. I’ve also written numerous articles about quantum compiling for this blog.

QC Ware Prices on April Fools Day 2020

Filed under: Uncategorized — rrtucci @ 5:44 am

So a friend told me that QC Ware has 4 rigid plans

– $2,500 for 1 hr. of QCT
– $25,000 for 11.1 hrs. of QCT
– $100,000 for 50 hrs. of QCT
– $500,000 for 333.3 hrs. of QCT

If RCT = real compute time, QCT = RCT on the DWave machine and (0.01)*RCT on a classical simulator. As you can well understand, it’s April Fools day so I am very suspicious of my friend’s assertions. Pretty funny, LOL. He had me there for a moment! Please help me out here. Tell me that my best friend is lying to me. Nobody is so foolish as to charge or pay that amount of money for the use of a computer that is less precise than the first MS-DOS pc.

That same friend is such a joker. He just told me that XanaduAI used to have a big picture of Seth Lloyd in their website proclaiming him to be their principal scientific adviser. And now, all of a sudden, no picture or mention of good ole Seth in their website. When he told me that, I nearly peed my pants laughing. I said to him, “Sir, that is absurd, what kind of a fool do you take me for? A Canadian would never abandon a loyal friend in his hour of need!”.

March 19, 2020

Kill Google

Filed under: Uncategorized — rrtucci @ 6:35 pm

killall-google2 #killgoogle
During times of upheaval and uncertainty such as these, some will make huge financial fortunes, while others will loose theirs. Now is the time for you to invest in my small company and make your fortune. Are you ready to take on the Google Tyrannosaurus Rex and beat it with me? I’m sure I know how to do it, albeit in one narrow, specialized market. A small company can’t beat Google at everything, but it certainly can beat them in a narrow market. Remember, the Tyrannosaurus Rex had a brain as big as a walnut.

“There is a tide in the affairs of men, Which taken at the flood, leads on to fortune. Omitted, all the voyage of their life is bound in shallows and in miseries. On such a full sea are we now afloat. And we must take the current when it serves, or lose our ventures.”


Quantum Optimization example for Tensorflow Quantum and Pennylane

Filed under: Uncategorized — rrtucci @ 5:57 pm

Recently, someone called Patrick Huembeli published an article in Reddit with the same title as this blog post. This was my reply.

IMHO, Pennylane doesn’t stand a chance against TFQ. You are wasting your time comparing the 2. Google won’t stop changing TFQ until it outperforms Pennylane in every possible way. I expect that IBM will answer with a bundle of its own, maybe one linking Qiskit and Pytorch/Pyro. Those are the two software bundles that you will be comparing six months from now: Google TFQ versus IBM PytorchQ. By then, Xanadu will have gone bankrupt. By the way, Scott Aaronson is on record as saying in his blog that Xanadu’s proposed qc applications are commercially worthless because they can all be performed much more efficiently on a classical computer.

March 9, 2020

Google Releases TensorFlow Quantum

Filed under: Uncategorized — rrtucci @ 7:21 am

Today, Google published the following paper:

TensorFlow Quantum: A Software Framework for Quantum Machine Learning, https://arxiv.org/abs/2003.02989

TensorFlow Quantum is software for doing Quantum Bayesian Networks. QB nets have been a dream of mine for 24 years, although Google’s paper, despite having 20 authors and 129 references, never cites any of my work. When I first had the idea of Quantum Bayesian Networks, I thought it was such a cool idea that, within a span of a year, I published a paper, filed for a patent and wrote a computer program called Quantum Fog about it (The original Quantum Fog was for the Mac. It was written in C++, with the GUI written using a C++ class library called PowerPlant. Much later, I re-wrote Quantum Fog in Python and released it as open source at github).

It was the first paper I ever posted on arXiv, and the first patent I ever filed, and the first and last 🙂 Macintosh program I ever wrote. The patent expired on 2016-01-11, but Google Tensorflow was first released to the public on Nov 2015, so maybe I can sue them for 5 bucks? 🙂

This blog, now 12 years old, is called Quantum Bayesian Networks for a reason: my intense passion and belief in this dream of mine.

Note that Tensorflow Quantum is a Tensorflow implementation of an earlier Google software called TensorNetwork. I am glad that they are now calling it Tensorflow instead of TensorNetwork. The word TensorNetwork implies an undirected graph whereas the word TensorFlow implies an acyclic directed graph (DAG), as befits a Bayesian Network. I wrote an earlier post about Google’s TensorNetwork software

Google’s TensorNetwork software versus Quantum Bayesian Networks

Screen shots of Mac Application Quantum Fog, first released about 20 years ago:

January 16, 2020

So which is better for portfolio optimization, a NISQ Quantum Computer, or Fujitsu’s “quantum inspired digital annealer”?

Filed under: Uncategorized — rrtucci @ 5:21 pm


Quantum computers come in 2 varieties, quantum annealers and quantum gate models. So far, DWave is the only company selling quantum annealers.

A third type of device is now available from Fujitsu. Fujitsu calls its device a “quantum inspired digital annealer”. The Fujitsu device does not have any quantum correlation (quantum entanglement) between separate qubits, so, in that sense, it is not a real qc, and Fujitsu doesn’t claim it is, only that it is “quantum inspired”. DWave, on the other hand, does claim partial quantum entanglement between the separate qubits of its annealer. The Fujitsu device is an optical device which operates at room temperature whereas DWave and most gate model qcs to date operate at milli-kelvin temperatures. Such extremely low tempreatures require expensive refrigeration equipment to maintain.

For the foreseeable future, gate model quantum computing hardware companies that already have devices (IBM, Google, Rigetti, IonQ, Intel, etc.) will only offer what they refer to as NISQ (Noisy Intermediate Scale Quantum) quantum computers. Such computers perform only partial or no error correction on their qubits. qcs are very prone to error. Eventually, in the far future, the aforementioned gate model qc companies hope to develop FTEC (Fault Tolerant Error Corrected) qcs, which are qcs that are fully error corrected. FTEC is an onerous task; so far, the best methods for doing FTEC utilize as many as 1,000 noisy “physical” qubits to produce a single, noise-free, virtual (“logical”) qubit.

There are many companies that do portfolio optimization with classical MCMC (Markov Chain Monte Carlo) ; for example, Quantopian, based here in Boston, where I live.

Portfolio optimization has been proposed by 3 competing factions, 1. DWave, 2. Fujitsu and 3. the NISQ qc hardware companies, as a task that could be performed more economically or faster with their devices than with current classical computers.

Are these 3 competing factions right about beating classical computers, and who of the 3 can do it better?

The purpose of this article is not to answer this question, but rather, just to pose it, and to stress that the FinTech industry is very interested in its answer. The 3 competing factions should be very interested in answering it too, because their profitability in the near term future might depend on its answer. Indeed, if, for example, it turns out that Fujitsu is much better than the other 2 factions, then Fujitsu could end up denying, to the other 2 factions, any significant market share in the affluent and lucrative FinTech industry. Fujitsu might deal a deadly blow to the nascent qc industry, and to the other annealer company, Dwave. Other possible scenarios are that someone shows that classical computers can still beat all 3 factions, or that a new company with a new device, either classical or quantum, joins the fray soon, and proves itself superior to all others.

Of course, if our dreams of building the fabled fully-error-corrected qcs ever come true, then those fabled qcs will be able to perform, according to the scientific theory, much better than the devices of the 3 aforementioned factions. But that is a distant pipe dream for now.

Some references

January 12, 2020

Report reveals that Seth Cesspool Lloyd took $285,000 from Epstein

Filed under: Uncategorized — rrtucci @ 8:36 pm

I’ve written in this blog 2 previous posts (first, second) on the connection between Jeffrey Epstein and quantum computing superstar, Seth Cesspool Lloyd .

Allegedly, Lloyd first met Epstein in 2004 at a John Douchebag Brockman “The Edge” dinner. Today, Lloyd continues his active participation in “The Edge”, an Epstein money laundering operation, while, at the same time, he publicly professes deep, heartfelt remorse for taking money directly from Epstein. A simple ArXiv search reveals that Lloyd acknowledged Epstein in 19 of his ArXiv papers. Also, a picture widely available on the internet shows Lloyd at Epstein’s Lolita island during a scientific gathering there in 2007. Recall that Epstein was convicted in 2008. Lloyd has admitted to visiting Epstein while Epstein was in prison.

A new development in the case is that a report commissioned by MIT and done by an independent law firm, Goodwin Procter LLP, was just released on Jan 10, 2020. As a consequence of that report, Lloyd has been put by MIT on paid administrative leave.

Here is a link to the report and some of its new findings regarding Lloyd.


According to the report,

  • In 2005 or 2006, Lloyd received a gift of $60K from Epstein. He never reported that gift to MIT. The investigators of the report were the first to uncover this gift and reveal it to the public.
  • In 2012, Lloyd received 2 gifts of $50K each. Excerpt from the report:

    the evidence shows that Epstein planned the donations to test whether MIT would accept his money notwithstanding his criminal record. Specifically, Epstein was disappointed that other academic institutions would not accept his money following his 2008 conviction, and, as Epstein put it (using a fishing metaphor) in an email to Professor Lloyd, “im going to give you two 50k tranches to see if the line jingles.”

    This time, instead of reporting that Epstein was the donor, Lloyd reported that someone else, an Epstein assistant, Lesley Groff, was the donor. When MIT phoned Groff about the donation, she revealed that the true donor was Epstein. Nevertheless, the donation was allowed to go through by the MIT officers in charge.

  • In 2017, Lloyd received a gift of $125K from Epstein, which he used to take a sabbatical. This time the donor and donation amount were apparently properly reported to MIT.

The report discusses in detail 9 red-carpet visits of Epstein to the MIT campus.

December 30, 2019

Scott Aaronson excoriates two quantum startups, Xanadu and Zapata

Filed under: Uncategorized — rrtucci @ 3:08 am

Check out the latest blog post by Scott Aaronson in his blog “Shtetl Optimized”

Quantum computing motte-and-baileys

On Dec 2019, a quantum startup called QCWare held a conference called Q2B19, which stands for Quantum to Business 2019. The conference was covered on Twitter under #Q2B19. Price of admission was a paltry 🙂 $1500/person.

Two quantum startups, Xanadu AI and Zapata Computing, unveiled at Q2B19, to much fanfare, new quantum algorithms. In the above blog post, Scott Aaronson argues quite convincingly that the outputs of those quantum algos can be calculated as fast or faster with a classical computer. I see no reason to doubt Scott’s expert analysis of Xanadu’s and Zapata’s quantum algos.

I’ve written previously in this blog several articles denouncing Xanadu as a scam company and a pyramid scheme. I call them a scam because they’ve promised to build a quantum computer based on squeezing, but are advancing at a glacial, lackadaisical pace towards that goal. Their main competitor PsiQuantum has 6 times more funding ($230M versus $40M), and a much more promising photonic technology.

Xanadu and Zapata are owned mainly by VCs; each has more than $40M VC funding but no practical products or net profit in sight yet. That is usually a prescription for disaster. VCs are most concerned with making a short term NET profit for their investors. Short term here usually means 3-5 years. I see no way that Xanadu or Zapata are going to achieve a net profit in 3-5 years.

Successful entrepreneurs usually have a profitable product **before** they go to the VCs. They either avoid VC funding altogether, or they use it only as a last resort to scale up the sales of their product. This is all very basic business knowledge. I am a PhD Physicist with very little knowledge about business matters, but even I know this.

December 18, 2019

Baby Yoda drinking the Quantum Kool-Aid

Filed under: Uncategorized — rrtucci @ 8:10 am


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