Thursday, July 11, 2019

On The Dowling-"Neven" Law

In a recent article in the magazine Quanta, much ado was made about the new so-called Neven's law: 

"That rapid improvement has led to what’s being called 'Neven’s law,' a new kind of rule to describe how quickly quantum computers are gaining on classical ones. The rule began as an in-house observation before Neven mentioned it in May at the Google Quantum Spring Symposium. There, he said that quantum computers are gaining computational power relative to classical ones at a 'doubly exponential' rate — a staggeringly fast clip."

Hartmut Neven is the director of the Google Quantum Artificial Intelligence Lab. In some sense — at least for the quantum cognoscenti! — this is a trivial observation. We have known for well over 30 years that the processing power of a quantum computer scales exponentially in the number of qubits. Hence, when the point came that the number of qubits on a chip began to grow exponentially, it is simple to deduce that the processing power will grow doubly exponentially. 

Nevertheless, the general public has difficulty grasping ordinary exponential growth — much less doubly exponential growth! So in my 2013 book, Schrödinger's Killer App: Race to Build the World's First Quantum Computer, I wrote an entire short section on this double-exponential growth in processing power. At the time I called it "Moore's Law for Quantum Computing." 

This double exponential growth has reached a stage where it is a reality, as Neven noted, since the number of superconducting qubits on a wide variety of platforms is doubling every six months. I thought it would be useful to set the historical record straight by posting here the excerpt from my book that discusses the double-exponential scaling, a feature of quantum computers that I propose we call the Dowling-Neven Law, given that I cooked it up six years before Neven did. 


Excerpt from: Schrödinger's Killer App: Race to Build the World's First Quantum Computer, by Jonathan P. Dowling (Taylor and Francis CRC Press, 2013) pp. 391–392. 


"I will take [Bill] Phillips up on his wager and bet that we have a quantum computer capable of running Shor’s factoring algorithm in 50 years or so. I will also take the science fiction writer point of view and extrapolate wildly beyond known physics to get us there. (Remember, the science fiction writers are more often right than the too conservative scientists.) There is consensus in the community that such a practical factoring engine will require around a trillion (1012) qubits. Conjecturing something like Moore’s law for quantum computing I will further conjecture that new technologies are around the corner that will allow us to double the size of our quantum processors every few years. So if we think of the new NIST ion trap working this in a few years (2020) with 1000 entangled ions we then just scale this up, doubling the number of qubits every few years, until we get to a billion entangled qubits. In figure 6.4, I plot this trajectory with the number of qubits on the red horizontal scale, the size of the corresponding Hilbert space on the green vertical scale, and the year along the diagonal on the orange scale. I show a few qubit ion trap photograph around the year 2000, a 1000 qubit ion trap around the year 2020, a fanciful rendition of a 100000 qubit machine made from a carbon graphene lattice in 2040, and then I run out of ideas for the hardware. But you can bet that scientists in 2040 will not run out of ideas (they have thirty years of new discoveries in hand that I don’t) and they will build the million qubit machine by 2060 and finally the Internet hacking billion qubit machine running Shor’s algorithm (for which I display the quantum circuit) by 2080. The growth in the number of qubits, as per Moore’s law, is exponential by year. Since the size of the Hilbert space, vertical green scale, is exponential in the number of qubits it is therefore super exponential. Following this trajectory, if I hedge William Phillips bet and we have a billion qubit machine in 70 years by 2080 then we humans will have explored 3000000000000 (three-trillion) orders of magnitude in size in Hilbert space. That is to be compared to the rather paltry 60 orders of magnitude in three-dimensional space humans have explored in all of recorded history, tens of thousands of years. The exploration of all of three-dimensional space in all of human history is nothing compared to the exploration of Hilbert space in the next 70 years. That is the promise of quantum technology.

Taking that position that Hilbert space is real, just as real as three-space, and then this is not just a mathematical exercise. If Hilbert space is a physical resource then by 2080 we’ll have a 103000000000000 dimensional resource at our disposal. It is difficult to wrap your brain around the size of this number.[i] This is a one followed by three trillion zeros. This book you are reading has around a million characters in it. Hence to print out the number 103000000000000 in full on paper would require a printing of 3000000 (three-million) books this size filled with all zeros; that is about a tenth of all the books in the US Library of Congress, one of the largest book repositories in the world. The number of particles in the entire universe is only about 1080 or one followed by only 80 zeros. In the Church of the Larger Hilbert space we believe that not only are these huge numbers attainable but that they are attainable in a generation and that they correspond to the size of a real thing, Hilbert space, that we can build things with using it as a resource. What is in Hilbert space? Well nothing I’m sure at the moment. That is whenever we opened a new window in three-dimensional space, by inventing the telescope or microscope; we found things that were already there, new planets in the former case and microbes in the latter case. This is why the exploration of three-dimensional space is a science. As our observing tools see bigger or smaller things we find stuff that has been there all along but that we just could not see before. Not so in Hilbert space. Hilbert space is not independent of us, there for us to find stuff in, but rather we create Hilbert space and then use it in turn to power new types of machines. The exploration of Hilbert space is much less a science and much more of a technology. I rather doubt that when we build the billion-qubit quantum computer that it will open a portal into an exponentially large Hilbert space that contains Hilbert space creatures that will leap out at us and gobble us all up. Rather then Hilbert space is empty until we make it and begin to manipulate our quantum mechanical states inside of it and fill it with our technologies. It is because we make it that it is a technology. What will we make in a 103000000000000 dimensional Hilbert space? Well there is plenty of room in there so I would be surprised if all we came up with was a quantum computer.

Figure 6.4: Exponentially large Hilbert space over the next fifty years. The red horizontal scale assumes a type of Moore’s law for quantum processors with the number of qubits in the processor following an exponential growth doubling in size every few years. (This is the type of scaling we’ll have to have if a universal quantum computer with a billion qubits is to be built in fifty years.) The dimension of the Hilbert space scales exponentially again with the number of qubits and so it scales ‘super’ exponentially along the vertical green axis. The diagonal orange arrow indicates approximate year. The figures show an ion trap quantum computer with one, two, three six, and ten qubit (lower left) where ten qubits gives a Hilbert space dimension of 210 or about 1000. The second graphic is the NIST ion trap that may have 1000 entangled qubits in 2020 with a Hilbert space dimension of 21000 or 10300. The third graphic is a schematic of the carbon graphene structure that might have 1000000 entangled qubits or a Hilbert space of 21000000 that is about 10300000. The final graphic (upper right) is a circuit for Shor’s algorithm running on a billion-qubit machine (of unknown technology) that has a Hilbert space dimension of 2100000000000 or 10300000000000. This chart implies that we will cover 300000000000 orders of magnitude of Hilbert space in the next fifty years compared to 60 orders of magnitude (figure 6.3) in three-dimensional space covered in the past several thousand years.[ii]

[i] See, “The Biggest Numbers in the Universe,” by Bryan Clair in Strange Horizons (02 April 2001) <>.
[ii] The figure is a composite. The two ion trap photos are courtesy of NIST and as work of the US Government are not subject to copyright. The graphene molecule, a two-dimensional crystalline form of carbon that has been proposed as platform for quantum computing, is a schematic that is the work of Krapnik <> and the circuit diagram of Shor’s algorithm was created by Bender2k14 <> and both are and licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Saturday, November 17, 2018


The Linotype (“line of type”) was a typesetting machine for setting metal “hot type” letters for a printing press. Each keystroke injected molten metal into a mold and the Linotype would produce an entire line of metal type at a time in a single metal ingot. 

The Linotype letters were arranged in order of frequency of use in the English alphabet, and so ETAOIN SHRDLU were the letters of the first two vertical columns on the left side of the keyboard and approximate the most common letters in English from most common to the left “E” and less common to the right “U.” 

This should be compared to the QWERTY typing standard in English keyboards, which was purposely designed with some of the least common letters on the primary row in order to slow typists down to keep them from typing so fast that they jammed the keys of the first mechanical typewriters. 

Etaoin Shrdlu was the title of a short story by Fredric Brown about a sentient Linotype machine of the same name. 

SHRDLU was the name of an artificial intelligence program developed in 1972 in the programming language LISP. (Thanks to Tony Schneider for this information.) 

The last issue of the New York Times composed using the Linotype machine appeared in July of 1978, and the typesetting of that last issue was captured in the documentary film Farewell Etaoin Shrdlu.

Schrödinger's Killer App: Race to Build the World's First Quantum Computer (Page 127). Taylor and Francis CRC 2013.

Linotype machine Model 6, built in 1965 (Deutsches Museum), with major components labeled. 

The notion that a sentient Linotype machine was at work, came about from a curious design flaw in the machine. As the typesetter typed away, there was no back or delete button. If you made a typo, your only choice was to start that entire single bar of type over again. To do this quickly, the typesetter would just type ETAIONSRDLU over and over again, because that was the easiest thing to type quickly and eject the flawed line of type into the recycling bin where it would be melted down again for reuse. But occasionally the typesetter would hit the send-to-print button instead of the send-to-recycling button. If that was missed by the editor, you would find "ETAONSRDLU" mysteriously in the middle of an article in the New York Times. These ghostly appearances gave rise to the rumor that a sentient gremlin by that name infested the printers at the NYT. Here is a famous example of such a typo from 1903.

File:Etaoin shrdlu.png
An October 30, 1903 article from The New York Times containing the linotype string w:etaoin shrdlu

Saturday, October 20, 2018

Post Quantum-Cryptography is the Off-Ramp on the On-Road to the Quantum Internet

In 1977, Rivest, Shamir, and Adleman proposed the first Public Key Encryption system, that now secures all of our financial data and much of our government data. 

The security rested on one premise, "We don't think computers can quickly factor large numbers." While the jury is still out on whether classical computers can quickly factor large numbers, we now know that quantum computers can quickly factor large numbers. 

I was at a meeting on quantum technologies on July 5th, 2018, in Munich. There, a chief scientist from Intel informed us that their conservative estimate for a universal quantum computer was 10 years. I asked, "Ten years or more?" She replied, "Ten years or less." 

Today the USA is ahead in the development of quantum computers. That lead will not last long. 

In part, due to that evanescent lead, the Chinese have decided to move to a quantum cryptography based system, which is immune to attacks by even a quantum computer. And they have invested $30B to develop a quantum computer of their own. 

In the meantime, the USA response to this threat is not to invest in a provably secure quantum cryptosystem, but rather to move to a "new" public-key crypto-system, post quantum-cryptograpy, which they hope—but cannot prove!—is immune to an attack by even a quantum computer. 

This is the US National Security Agency position on the matter, and their protocols are being tested, quantified, and standardized by the US National Institute of Science and Technology—ready soon to be rolled out.  

This is a fool's errand. 

This US approach to the threat posed by quantum computers is simplistic, nearsighted, and dangerous. 

Quantum key distribution uses an unbreakable one-time pad. This scheme is used by the US diplomatic corps, the CIA, and for the nuclear launch codes. Currently, the launch codes are distributed to the missile silos on 3.5" floppies driven around by a guy in a truck. Surely we can do better than that? 

And why are diplomatic communications, intelligence communications, and the nuclear launch codes secured with one-time pads? It is because that the users of these systems do not trust public key encryption, since it is not provable secure. Moving to a different un-provably secure public-key encryption system does not change this reality. 

The move embrace post quantum-cryptography is a move away from developing a quantum internet, for which no such public key is needed. The quantum internet is automatically secured by quantum cryptography. 

To quote myself, " The future of the quantum Internet is in photons and the short circuiting of the development of optical quantum information processors in the United States means that the future quantum Internet will have 'Made in China' stamped all over it." — Schrödinger's Killer App (2013). 

The future of the the quantum internet is certainly not post quantum-cryptography. 

We have a completely unbreakable quantum key distribution protocol — why the hell don't we use it!?

Post quantum-cryptography is a small band-aid on an arterial wound. 

Monday, October 15, 2018

A Brief History of The "Second Quantum Revolution"

I'm preparing a talk to present next week in Brisbane, Australia, to celebrate Gerard Milburn's 60th birthday, and I plan to focus on a paper we wrote together in 2002 that has now become a hot topic.

In 2002,  Milburn and I wrote the paper, "Quantum Technology — The Second Quantum Revolution" that appeared on the ArXiv in June of 2002 and was published in the proceedings of the Royal Society of London in August of 2003. The terms "quantum technology" and "second quantum revolution" have recently taken off.

Milburn had written a book in 1996 called Quantum Technology and so that phrase had been around for a while. Indeed a Google search of "quantum technology" from 1900–2000 shows hundreds of hits. However, a Google search of the same phrase over all time shows nearly 500,000 hits.

To get a better idea of the trend, using Web of Science, we find 913 peer-reviewed publications with "quantum technology" or "quantum technologies" in the title, abstract, or keywords. Here is the graph of the citations to those articles by year.

Citations by year to journal papers with "quantum technology" or "quantum technologies" in the topic.

One can see the number of citations goes from linear growth to exponential in the early 2010s.

More unique is the phrase "second quantum revolution".  According to Google, this term appears only once between 1900 and 2000, in 1997 in an unpublished manuscript, A History of Physics as an Exercise in Philosophy, by E. J. Post, on page 52, where Post writes, "This relation was to have a major role in implementing the Schroedinger wave equation; the latter and matrix mechanics set off the second quantum revolution."

Post was calling the transition from the old quantum theory of Bohr and Sommerfeld to the new quantum theory of Heisenberg and Schrödinger, "the second quantum revolution", which is not at all what Milburn and I had in mind for Quantum 2.0.  I suppose Milburn and I should have used the "third quantum revolution" but it is too late now.

If we now redo the Google search on "second quantum revolution" over all time, we get nearly 11,000 hits, as seen in the figure below. There is even a new book out with this phrase as its tile. (I hope the author Lars Jaeger cites us.)

Google gives nearly 11,000 hits for "second quantum revolution" all of which dated 2002 or greater.
Note Milburn's and my ArXiv paper appears second on the list. 

Let us now return to the Web of Science and find the citations to papers that cite Milburn's and my paper. The paper has been cited 132 times. The plot below is the number of times those 132 papers have been cited by year. Again we see a linear to exponential transition in the early 2010s.

The number of citations by year of the 132 papers that cite our original paper. 

So what are we to make of this charts? Milburn and I should have trademarked "the second quantum revolution" when we had a chance.

Palm Springs 1988 Cartoon

At the 1998 NASA Palm Springs conference on quantum computing, I showed the above cartoon before starting my talk on Friday, the last day. The monologue went something like this:

During this conference I've noticed a number of speakers presenting slides illustrating the goal of quantum computing as some far off unreachable dream castle, or slides attempting to illustrate how some large government bureaucracy is involved in quantum computing. In this cartoon I've attempted to combine both of these goals in a single slide, and also give some of my background role in government sponsored quantum computing.
So here at the bottom are the government agencies, represented by different characters from the Wizard of Oz -- or in this case --- The Wizard of Odd. Here I am, as Toto the dog, representing Army Aviation & Missile Command (AMCOM). The idea here is that most of the time it's just annoying to have a small yapping dog in your lunch basket -- but occasionally he alerts you to something you otherwise might have missed. This was the case in 1994, when I attended the International Quantum Electronics Conference (IQEC) in Anaheim (Baltimore?) in the Spring, and the International Conference on Atomic Physics (ICAP) in Boulder in the Summer. At the IQEC I first learned of the British Telecom results, where they succeeded in transmitting a quantum cryptographic key over 70 km of fiber. I contacted Henry Everitt (alias "Dorothy") at the Army Research Office (ARO) about this exciting result, and shortly thereafter the ARO planned a workshop in Tucson for the Spring of 1995 on quantum cryptography. Then, later that Summer at ICAP, Ekert gave a talk on Shor's algorithm, which began the Great Diaspora for quantum computing. It turned out that Cirac, Kimble, Wineland, Zoller, and many others from the quantum optics community were at this meeting, and they all went off afterwards to their various labs to get to work. For my part, I again contacted Everitt at the ARO about this exciting new "bolt from the blue", and it was decided to add quantum computing to agenda of the Tucson meeting. So it was that the first Army sponsored workshop on quantum cryptography and quantum computing came about in the Spring of 1995 in Tucson, Arizona, with many of the key players in the room here today present at that meeting.

Of course the Dorothy character representing the ARO in the cartoon bears no resemblance to any ARO employee, living or dead, no matter what you hear about what he does in the privacy of his own home. The ARO would like a quantum computer, of course, to plan out its logistical strategy for the invasion of Kansas.
At the Tucson meeting I met for the first time Keith Miller from the National Security Agency (NSA) -- who bears no resemblance to the Scarecrow in the cartoon, singing, "If I only had a (quantum) brain...." Keith was the only workshop attendee who had no affiliation whatsoever printed on his name tag, identifying him immediately by logical deduction as an employee of the NSA. Based in part of the results of this meeting, the NSA and the ARO decided to pool their resources and expertise in the DoD support of quantum computing.
With the ARO and the NSA now in cahoots, Henry and Keith were quickly able to round up the prodigious resources available from the Defense Advance Research Projects Agency (DARPA), and bring them to bear towards funding research on quantum computing. DARPA is depicted here as the Tin Man since, as you know if you've ever asked them for money, they have no heart.
Things were moving along smoothly for a time in DoD Quantum Computing land, when suddenly I got wind of this here NASA Palm Springs conference. The first question I asked, as I'm sure many of you did, was "Why the heck is NASA working on quantum computing!?" However, since the conference was in such a nice place and in the hopes that NASA might have gigabucks of research money to throw around -- we all showed up here in droves to attend what has been a splendid workshop, thanks to the efforts of Colin Williams and his co-workers. Hence, NASA is depicted in the cartoon as the Cowardly Lion, who took a while to find his courage to get into the field -- but now has come in with a roar.
Turning to the academic top portion of the cartoon, we see here in the upper right that the unreachable goal is depicted as The Emerald City of Quantum Computation, which is ruled over by The Wizard of Odd, who was meant to have absolutely no resemblance to Charlie Bennett. Opposing the Wizard is the Wicked Witch of Pessimism, who again bears no resemblance at all to Peter Knight. The "H"on her hat stands for "Hermitian" or "Hamiltonian" or perhaps even "Hadamard" -- but certainly not "Haroche". In order to reach the goal of quantum computation, Dorothy and her loyal companions must fight off the Witch's Flying Monkeys of Decoherence, but to their rescue comes the Wizard's Marching Error-Correcting Munchkins. Will they win the battle and eventually reach the Emerald City? Only time (and lots of government money) will tell.

-- Jonathan P. Dowling

Sunday, October 7, 2018

Dowling's Hollywood Debut

Dowling was a consultant to Steven Spielberg's prop department on the 2002 movie remake of the H. G. Wells book, The Time Machine.

Dowling provided all the equations and figures used in the movie, including those in the trailer and on all the chalkboards that appeared in the film. He carefully wrote down all the equations by hand and faxed them to Spielberg's Dreamworks studio in Hollywood, where the prop department transcribed them onto the chalkboards. While there are some transcription errors, these are all real equations, but not all about time travel.

In the middle you can see a graph, called a Minkowski diagram, showing the world line of the time machine going outside of the light cone; a hallmark of time travel into the future.

The appearance of the symbol Hg is not a reference to the element mercury, but rather a tip of the hat to H. G. Wells, the author of the original classic book, The Time Machine.

The triple integrals were taken from Dowling's 1988 PhD thesis, (with some artistic license) so they would become immortalized on film. For example,

In 2017, one of the original chalkboards, with  Dowling's equations preserved on it, was put on display at the Barbican Art Center in London in an exhibit titled, "Into the Unknown —A Journey Through Science Fiction."

Photo credit with permission from: JohannYellowdog 

While Dowling does not appear in the credits of the film, nor  on the description for this museum prop (called a "relic"), if you get the DVD of the film and check out the special features, you will hear the prop guys discuss how a "Scientist at JPL" made all the equations for them. JPL is where Dowling was working at the time in 2001. The Dreamworks prop guy that Dowling worked with was Scott Maginnis, and you can find their email exchange, preserved all these years, here. When Dowling asked Scott why Spielberg called on him to do these equations, Maginnis replied, "Stephen saw an article about your invention of quantum lithography on CNN, and told us that we needed to get you because you were a NASA physicist and would produce real equations." That CNN web page is also preserved and may be found here.

However, with no direct acknowledgment, like all good artists, you can see Jonathan Dowling's signature in the lower left.

Dowling also consulted for Sony Pictures on another time-travel movie, with the working title of Frozen, which was never produced. (No, not that Frozen.)

Sunday, August 5, 2018

Is Your Brain a Quantum Computer?

From Schrödinger's Killer App, Chapter six.
To close this section, this chapter, and this book I want to talk about quantum biology and particularly the notion that the human brain already is a quantum computer. We must remember that Searle’s strong classical AI hypothesis is just that, a hypothesis. Hypotheses in science must be tested. I like to think it is true and I hope in 20 years or so, when our electronic computers have the same number of transistors and interconnects as our brain has neurons and synapses, we’ll find out. But if the classical computers continue to become more and more powerful without showing signs of self-awareness then perhaps other hypotheses should be considered. Quantum biology is a new area of research that postulates that what I will call the ‘weak’ quantum biology hypothesis. We have seen in this book that quantum physics, particularly quantum entanglement, offers an advantage over classical physics in computational power (on some problems) and in sensing and imaging (in some systems). Often, when nature offers a survival advantage that that biological life form will evolve to take advantage of it. Biological life forms take advantage of light sensors (eyes), sound sensors (ears), touch sensors (skin), and computational power (brains). The better you can see, hear, sense touch, or think the more likely you will be able to survive and pass on your genes for such things. The quantum biology hypothesis states that, since quantum mechanics offers advantages in sensing, imaging, and computing, biological systems should evolve quantum-based sub-systems to take advantage of those advantages. That is, according to the hypothesis, since biology takes advantage of any physiological edge offered to it, there should be biological life forms that already taking advantage of such uniquely quantum features as quantum unreality, uncertainty, and nonlocality.[i]

The US Defense Advanced Projects Agency even has a program in quantum biology. American physicist and DARPA program manager Matthew Goodman runs this program. When the program had its kickoff meeting in September of 2008, and somewhat to my puzzlement, Goodman invited me to attend. As I recall I talked to him on the phone and protested that I did not really know much about biology, quantum or otherwise, and that I was not working in the field. Did he really want me to attend and if so, pray tell, why? The answer was that I was to sit in front as skeptic-in-chief and use ‘the best bullshit detector in the business’ to advise him one what might be good avenues to pursue for research and what might be just a little nuts. I did not know much biology but I sure did know quantum mechanics. This was a role I aspired to. So I showed up in the DC area for the two-day workshop, sat in front next to Goodman, and proceeded to heckle all the speakers. Some of them became a bit irritated with me at first until Goodman and I explained my role and then they lightened up. In fact I think I was useful. Some of the talks seemed sound but some, to me, seemed to be nothing more than quantum numerology. After the conference I gave Goodman my advice on what seemed like good ideas to follow up on and what seemed just silly and every since I have kept one eye on the field of quantum biology. The two particular areas of current interest are in photosynthesis and bird migration. It appears in some photosynthetic bacteria that live in water deep enough to be dark the bacteria harvest photons with an efficiency that cannot, yet, be explained with classical theory alone. The photons arrive at an antenna-like ‘light harvesting’ structure in the photosynthetic bacteria and then with a very high probability, much higher than classical physics can explain, the photon energy is transported to a reaction chamber where it is converted into chemical energy to power the bacteria.[ii] My complaint about this claim, at least in 2008, was that the experiment that demonstrated the effect was carried out at the frigid temperature of liquid nitrogen, which is –196°C (–321°F). Those bacteria are not doing anything at such a temperature — they are frozen solid! The experiment was suggestive but certainly not conclusive. I recommended DARPA fund the experimenters to redo the experiment at room temperature. Biological organisms on Earth are not selecting for anything at –196°F; they are dead. The experiments have been done at room temperature and although the effect is not quite as startling but — much to my surprise — at least some great degree of quantum coherence, quantum unreality and cat-states, survives at room temperature.[iii] I’m puzzled by this result in that in the world of quantum technology often objects must be cooled to very cold temperatures for quantum coherence to survive. As things are heated up the thermally fluctuating environment should tend to destroy the coherence at room temperature. Perhaps nature has, over millions of years of evolution, found a way to protect quantum coherence in warm biological environments or mitigate the effects of the swirling thermal fluctuations in the hot soup of life. Why on Earth is DARPA interested in this stuff? Well if bacteria have found a way to make more efficient photon absorbers perhaps we can learn from them Rather than spend billions on making improved photon collectors for solar cells we just lift the technology out of the bacteria and place it solar panels on our roofs.

A second canonical example of what is suspected to be a quantum biological magnetic field sensor in the brains of migratory birds or more particularly their eyes. It has been known for thirty years that some birds use the very weak Earth’s magnetic field to navigate over trans-global distances. The problem is that all known mechanisms from classical mechanics and ordinary chemistry cannot explain the sensitivity of any biological magnetic field sensor that could do this. So after thirty years it is time to give the quantum biologists a chance. What is known is that the magnetic field sensor is activated when light hits the eye of the bird. The weak quantum biology hypothesis is that the evolutionary advantage to a migratory bird of having and Earth magnetic field sensor would be so strong that if any such mechanism ever arose by chance mutation the evolutionary amplification process of natural selection would size upon it and develop it into a quantum bio-technology that would benefit future generations of bird brains.

The model is that the photons striking the bird retina create a pair of spin-entangled electrons in a chemical reaction, and then those spins respond to the magnetic field with a signal-to-noise greater than say the spins of two uncorrelated electrons. One proposal is that when the pair is one of the four possible two-spin quantum states it produces a chemical that it does not when it is in one of the other three spin states. The strength and orientation of the field determines how many of the pairs are in the one versus three states, and so it is presumed, affects the rate at which the chemical is produced. Then somehow, it is not clear, perhaps the bird sees something it its eyes that corresponds to the magnetic field direction and strength and then uses this information to steer itself on its bi-annual migrations north or south. Again my concern is that quantum entanglement, and the required quantum coherence required to produce it, is very fragile and very quickly destroyed by the thermal fluctuations in the biological environment of a relatively hot living bird. But perhaps evolution has found a way to protect the entanglement that we have not. Evolution is a powerful thing. Or maybe the entanglement only needs to survive a few nanoseconds to do its job and produce the right ratio of chemicals that color the magnetic field across the bird’s field of view. Again, DARPA never met a magnetic field sensor it didn’t like. If we could reverse engineer this quantum bio-technology perhaps we could build room temperature super-sensitive magnetic field sensors that we could then integrate into a chip, the size of a grain of sand, and implant behind our ears to read our minds and allow our teenagers’ teenagers’ teenagers’ teenagers to carry out oblivious pseudo-telepathy with each other [127].

This leads me to what I will call the strong quantum AI biology hypothesis. This hypothesis has, which today has few followers, been most forcefully argued by British mathematical physicist Roger Penrose in his 1989 book The Emperor’s New Mind, and less forcefully argued by our old friend Henry Stapp in his 1993 tome, Mind, Matter, and Quantum Mechanics.[iv] The strong quantum AI biology hypothesis is in direct contradiction to Searle’s strong classical AI hypotheses, and it states that no appropriately programmed classical computer with the right inputs and outputs, no matter how powerful, will ever have a mind in exactly the same sense human beings have minds — that is human minds are fundamentally different than classical computers and that quantum mechanics is required to explain human consciousness. That is, the strong quantum AI biology hypothesis posits that the human mind is in fact already a quantum computer; that hundreds of thousands of years ago some quantum effect or effects arose by mutation in the mind of our ancestors and gave our brains a computational advantage over the rival progenitors running on meat processors only. As evolution is wont to do, this slight computational advantage was greatly amplified through the process of natural selection until it produced the end result; the human mind. The strong quantum AI biology hypothesis states that we have already met the sentient quantum computer and that he is us!

Stapp’s argument stems from his belief that that human mind routinely engages in ESP and that quantum entanglement is needed to explain ESP and so the human mind must be fundamentally quantum. As I have argued vociferously above, after 50 years of controlled experiments, there is absolutely no evidence for ESP and plenty of evidence against it. ESP does not exist and so there is no need to posit quantum mechanical processes in the brain to explain it. Stapp’s logic seems to me to be that he does not understand how quantum mechanics works, and he does not understand how ESP works, and so he argues that quantum mechanics is required to explain his how the mind engages in ESP. I dismiss this argument out of hand since ESP does not exist and so does not need explaining. Trickier is the argument of Penrose. Penrose simply rejects the strong classical AI hypothesis. That is Penrose declares, without any evidence to support his position, that no classical computer, no matter how powerful, can ever have a mind in the same way that a human has a mind. I have read his book and heard him talk on the subject and as far as I can tell his argument goes like this. Penrose does not understand how quantum mechanics works, and he does not understand how his brain works, and hypothesizes the quantum mechanics is needed to understand the working of the mind. I suspect Penrose just looks at his desktop PC and thinks that, There is no way that thing will ever be as smart as me!” To be fair there is no evidence for the strong classical AI hypothesis but we might want to rule it out first based on experiment before invoking the strong quantum AI biology hypothesis. Revulsion at the thought of your desktop PC someday having a mind equivalent to your own is not experimental evidence for rejecting the strong classical AI hypothesis. Those of us who watch the television series Star Trek not only find some appeal in machine minds but I daresay some of us even identify with such android humanoids such as Lt. Commander Data.

The problem that I have with Penrose’s strong quantum AI biology hypothesis is similar to that I had with the light harvesting bacteria and the magnetic bird sensor. Delicate features of quantum weirdness, unreality, uncertainty, and nonlocality, are easily destroyed by the thermal fluctuations of the environment, which are particularly severe in hot-blooded animals such as birds and humans. As American astrophysicist Carl Sagan was fond of saying, “Extraordinary claims require extraordinary evidence.” The claim that that some bacteria have evolutionary exploited weak quantum effects to make better photoreceptors or the claim that some birds have evolutionary exploited weak quantum entanglement to make better magnetic fields sensors are not extraordinary claims and so a few tight non-extraordinary experiments on the bacteria and the birds should be enough to prove this one way or another to my satisfaction. I will be a little surprised if the weak quantum biology hypothesis turns out to be true but when I am surprised I am happy. If these experiments pan out then it will be very interesting to learn what nature has done to protect these weak quantum effects from the thermal environment and indeed perhaps we can exploit what nature has done to make better photoreceptors and magnetic field sensors.

However Penrose’s strong quantum AI biology hypothesis is orders of magnitude more extraordinary and so the evidence to prove it needs to be orders of magnitude more extraordinary. It is a long way to go from nature having found a way to protect a few quantum states so that pigeons can migrate to nature has found a way to build a large-scale quantum computer in our noggins so that we can think. In The Emperor’s New Mind, Penrose offered no concrete model for just how quantum entanglement would lead to consciousness.[v] It was just a lot of wishful thinking and the reviling of the strong classical AI hypothesis. After falling into cahoots with the notorious anesthesiologist and hawker of quantum consciousness, Stuart Hameroff, Penrose published a 1994 book called Shadows of the Mind, where he proposed changing quantum theory to fit his hypothesis of quantum consciousness and further proposed that, without any evidence whatsoever, that there are ‘microtubules’ in the brain that somehow store and protect from thermal noise the fragile quantum entangled states purportedly needed to explain human consciousness.[vi] My bullshit detector simply pegged. Change the laws of quantum mechanics to fit your hypothesis? Postulate, with no evidence, microtubules in the brain to support your hypothesis? When you start changing the rules of the game to fit your pet hypothesis this then is the hallmark of pathological science.[vii] To summarize there is, in spite of a brief experimental search, no evidence of ‘microtubules’ in the brain that store quantum states, much less that the brain uses them as quantum processors to generate human consciousness.[viii] As far I can see there is also no reason at all to change the laws of quantum mechanics — the most successful theory of all time.

What is Penrose’s beef with the classical computer? From reading The Emperor’s New Mind it is difficult to tell as that book is all over the map. The reader is introduced a wildly disparate collection of topics such as Newtonian mechanics, quantum mechanics, cosmology, and quantum gravity before Penrose attacks the strong AI hypothesis in the last couple of chapters. No physicist in his or her right mind would think quantum gravity has anything to do human consciousness. Nor would any evolutionary biologist. Again it is one thing to posit that evolution has made better bacterium photoreceptor using bits quantum flotsam and jetsam and quite another thing to propose that evolution has harnessed the hypothesized quantum fluctuations of space and time in order to build a human mind. The human mind is about 10 centimeters across while quantum fluctuations in space are about 10–33 centimeters across. How on Earth would evolution in a series of gradual steps bridge those 32 orders of magnitude in distance to harness quantum gravity and why on Earth would it need too? Once you dig through mountains of chaff in his book you find one single kernel of barley. Writing in 1989, Penrose complains that all electronic computers of that age are classical universal computers in the Turing sense, which is equivalent to a classical Turing machine, and for that reason can never mimic the behavior of the human mind. He might have had a point in 1989 but since then all sorts of new classical computing paradigms have sprung up. Searle’s strong AI hypothesis states, “The appropriately programmed computer with the right inputs and outputs would thereby have a mind in exactly the same sense human beings have minds,” but never specifies that the computer must be algorithmically equivalent to a Turing machine. The claim that all electronic computers must be equivalent to ordinary Turing machines is Penrose’s own personal straw man, which he then merrily ignites with a blowtorch and then dances gleefully about the flames whilst lobbing Molotov cocktails in the pyre.

The reader may wonder why at this very late junction I have decided to hammer on Penrose and then Hameroff. Well aside from the point that the Rube Goldberg constructions, modified quantum theory and unseen microtubules, they require to provide a quantum basis for human consciousness are just silly, there is no need to invoke such a quantum basis, at least not yet. The idea that human consciousness is quantum based, Penrose’s strong quantum AI biology hypothesis, is an extraordinary claim. But in spite of all the smoke from his smoldering smudge pot of his burning straw man, I find very little in the way of flames. There is no evidence at all to support this claim much less the extraordinary evidence that Sagan would require. There is no reason yet at all to rule out Searle’s strong classical AI hypothesis. Penrose’s quixotic attack on the Turing machine model of computation is completely off base. The real surprise is that Turing’s simple model of computation has taken us as far as it has and not that it is the end of the story of classical computation. As I have related above, neuroscientists conjecture that human consciousness lies all in the synapses, the interconnects in the brain.

When Penrose penned his first book in 1989 on this topic, The Emperor’s New Mind, the science of artificial neural networks was mildly popular. Now it is wildly popular. Neural networks are models of very classical computing that are actually taken from models of the human brain. Lots of transistors, lots of interconnects, and lots of feedback loops. Some artificial neural networks are equivalent to Turing machines but others appear to be super-Turing, which is they have properties that transcend the simple computational model of computing Turing proposed eighty years ago. Penrose is attacking an eighty-year old model of computing. It would be a surprise if there had been no progress in classical computing since them. The field of super-Turing machines, while not without its own controversies, provides a framework where a neural network can carry out tasks not in the usual universal computing framework, the framework Penrose attacks. Particularly interesting is that super-Turing machines may have a reflexive or self-referential or highly recursive. That is super-Turing computers have a built in ability to think about themselves, a hallmark of human consciousness.[ix] Hofstadter in his 2007 book, I Am A Strange Loop, expounds on this idea an particularly makes the case that sufficiently complex but classical self-referential systems, such as possibly neural networks, will necessarily develop an illusion of self and therefore posses unique properties of a human mind. This is all not proved and worked out and itself constitutes and extraordinary claim, a sufficiently powerful artificial neural network will have a mind in the same way a human has a mind, but such a statement falls in the purview of the Searle’s strong AI hypothesis; Searle never claimed his powerful computer was a Turing machine, only Penrose claimed this. My point is that this neat set of ideas needs to be investigated and ruled in or ruled out before invoking quantum gravity or microtubules or whatnot to explain human consciousness. In 20 or 30 years we shall build (and perhaps eventually merge with) a powerful, self-referential, but still classical AI, a super-Turing AI, based on an artificial neural networks with a 100 billion transistors and a 100 trillion interconnects and we shall wait to see if it wakes up and talks to us and then passes the classical Turing test for consciousness. If it does not and then we continue onwards for 40 or 50 years with a trillion transistors and a quadrillion interconnects and still no sign of sentient life, well then we can start revisiting the strong classical AI hypothesis and perhaps reject it; but not now.

The reason I have spent so much time on Penrose’s proposal is that I think Searle’s strong classical AI hypothesis is right. Quantum mechanics need not be invoked to explain the human mind. I am, still in the end, proud to be a meat computer. But I also believe in my own strong quantum AI hypothesis, which I want to carefully peel away from Penrose’s strong quantum AI biology hypothesis. There will someday arise a quantum mind. The appropriately programmed and sufficiently powerful quantum computer, with the right inputs and outputs, have a mind in exactly the same sense human beings have minds, but it will have a mind that, unlike me, also thinks in Hilbert space and therefore super-exponentially transcends the human mind. If Penrose is right and my mind is a quantum computer, well then my mind is a particularly lousy quantum computer. I can immediately construct a question for the quantum Turing test that I myself cannot pass. Says the quantum mind to me, “Dowling! Can you factor this hundred-digit integer into its composite primes in under a second?” No, I confess, to it, I cannot. If Penrose is right and I am some sort of quantum computer then I am the crapola of all quantum computers. I make this point precisely so that when the true quantum technology based quantum mind comes online in a hundred years the acolytes of the Church of the Larger Penrose Space do not waive ancient tattered copies of his book about and declare victory — that Penrose was right all along and that consciousness does indeed require quantum theory. I would extol them to remember he only claimed that my meat computer, my mind, requires quantum theory and not that quantum mind that emerges from our quantum technologies in a hundred years. What will that quantum mind be? Well I can try to predict exponential growth but I dare not try to predict super-exponential growth. What will a self-replicating life form that thinks in Hilbert space be like? Well I don’t know but it will think in a fundamentally different way than I do. When it arises from our quantum technologies what we will it do to us, or what will we do to it?

But is your brain a quantum computer? Probably not. 

[i] See, “Quantum Biology,” in Wikipedia (Wikimedia Foundation, 12 August 2012) <>.
[ii] See, “Quantum Secrets of Photosynthesis Revealed,” by Lynn Yarris in Research News (Lawerence Berkely Lab, 12 April 2007) <>.
[iii] See, “The Physics of Life: The Dawn of Quantum Biology,” by Phillip Ball in Nature, Volume 474 (2011) pages 272–274 <>.
[iv] See, The Emperor’s New Mind, by Roger Penrose (Oxford University Press, 1989) <>; and Mind, Matter, and Quantum Mechanics, by Henry P. Stapp (Springer, 1993) <>.
[v] See, “The Emperor’s New Mind,” in Wikipedia (Wikimedia Foundation, 13 August 2012) <>.
[vi] See, “Is the Brain a Quantum Device?” by Victor Stenger in the Skeptical Inquirer, Volume 18.1 (2008) <>
[vii] See, “Pathological Science,” in Wikipedia (Wikimedia Foundation, 14 August 2012) <>.
[viii] See, “Shadows of the Mind,” in Wikipedia (Wikimedia Foundation, 13 August 2012) <>.
[ix] See, “Hypercomputation,” in Wikipedia (Wikimedia Foundation, 13 August 2012) <>.