Evidence of Quantum Computations in the Human Brain
Quantum biology is increasingly finding and exploring quantum processes in biological systems — in photosynthesis, birds, even human sensory systems. Why not the brain? In fact, some feats, such as superhuman computational abilities to factorize large numbers, could be pointing to quantum processes in the brain. This article explores this exciting possibility!
Quantum vs Classical Computers
The goal of a quantum computer is to perform computations that would be too computationally intensive and impractically long for a classical computer to compute. One of the problems, often cited in which a quantum computer will be able to do much more efficiently than standard classical computers (that’s the typical computer that is ubiquitous today) is to factorize very large numbers. Multiplying two large numbers is easy for any computer. But calculating the factors of a very large number, on the other hand, is often considered practically impossible for any standard computer. In fact, the challenge of factoring large numbers after encryption is what secures the internet and protects communications, our bank accounts, and other sensitive data.
In 2016, for example, it took several hundred standard computers two years to crack an encrypted message with a key that was 768 bits long. If it was a 1,024-bit key, it would have taken 1,000 times longer, and it is estimated that cracking the current highest standard of 4,096-bit key would exceed more than a billion years! So, the speed at which computers can crack encrypted messages determines our security, and conversely our vulnerability.
However, in 1994, Peter Shor, from the Massachusetts Institute of Technology (MIT), showed that, using his algorithm, a quantum computer could factor large numbers quickly and in principle easily crack encryption that is safe when using standard computers. The power of quantum computers can be assessed by the number of qubits (qubit = quantum bit) it can process. As at the end of 2020, the most powerful stable quantum computers have yet to pass the 100 qubits mark. However, quantum computers are in general getting more powerful.
Advanced Encryption Standard (AES) is an encryption algorithm that encrypts fixed blocks of data of 128 bits at a time and is probably the most common encryption method today. RSA (named after its founders) is a public-key encryption algorithm which is also popular over the internet. RSA-200 has 200 decimal digits (maximally equivalent to about 663 bits), and which can be factored into two 100-digit primes. The CPU time in identifying these primes by a collection of parallel computers would amount to approximately 75 years work for a single 2.2 GHz Opteron-based computer. However, for a quantum computer, a 128-bit or 256-bit encryption could be easily cracked by a 5 qubit computer, which was achieved in 2002 (see Figure 1 above).
Human Computers
However, some humans, it seems, are not far behind. Shakuntala Devi (who lived from 1929 to 2013) was an Indian writer and mental calculator, also known as the “Human Computer”. By the 1970s, she had become globally recognized for the astounding mathematical feats she performed in her head, some of which are highlighted below.
In 1977, Shakuntala found the root of a 201 decimal digits number in 50 seconds. What’s more, this was the 23rd root of the number — a much more difficult problem than just the square root solved by the computers to decrypt RSA-200 (as discussed above). In principle, if Shakuntala could break 663 bits (equivalent to the processing power of about a 9 qubits quantum computer), she would be able to crack most of the encryption on the internet today which is based frequently on 128 bits or 256 bits, with ease, much like a quantum computer. How could a human brain do it, in the absence of a quantum processor?
This is not an isolated case. There are many examples of superhuman abilities of autistic savants to factorize large numbers in the literature. Even a mentally deficient autistic savant was able to find the prime factors of 10- and 11-digits numbers (which is approximately 35 bits) in his head virtually instantaneously. All we currently know about the brain cannot explain this. Are human brains capable of using quantum processes to factorize?
How is Quantum Coherence Achieved in the Brain?
In 2013, researchers from the University of New South Wales (UNSW) created the first working quantum bit based on the spin of the nucleus of a single phosphorus atom, within a protective bed of non-magnetic silicon atoms with zero spin. In a ground-breaking paper in the journal Nature, they reported a record-high accuracy in writing and reading quantum information using the nuclear spin.
As the nucleus of a phosphorus atom has a very weak magnetic field and possesses the lowest spin number of ½ (which means it is less sensitive to electric and magnetic fields), it is nearly immune to magnetic noise or electrical interference from the environment. It is further “shielded” from noise by the surrounding bed of zero-spin silicon atoms. Consequently, the nuclear spin has a longer coherence time enabling information to be stored in it for a longer time, which results in a much higher level of accuracy.
Using basically the same set-up, Matthew Fisher, a physicist at the University of California, proposed a model where nuclear spins in phosphorus atoms in the human brain can serve as qubits. (Phosphorus is abundant in the brain.)
“Might we, ourselves, be quantum computers, rather than just clever robots who are designing and building quantum computers?”
Matthew Fisher
Fisher has argued quite convincingly that spins of the nuclei of phosphorus atoms in the human brain can be sufficiently isolated (by the protective cloud of electrons around it and the protective shield of a bed of zero spin atoms) and also be less “distracted” by quantum noise because of its weak magnetic field (due to its low spin number), thus allowing it to preserve quantum coherence. (The laboratory study by researchers at UNSW, discussed above has confirmed this fact.) So, even in an environment such as the brain, where electric fields abound, the nuclei of phosphorus atoms would be in a sufficiently isolated environment to do quantum computations.
To read more about Fisher’s model, please read the author’s article on The Quantum Computer in Your Brain.
Conclusion
If the human brain does indeed contain a quantum processor(s), we should not be blind to the possibility that everyone should be able to perform complex calculations (and more) in fractions of seconds. The reason why we may not see these superhuman feats being performed by most people is because the activities of neural processes that mimic processes in a classical computer dominate in a human brain. When this classical processor(s) is damaged or temporarily muted, however, as in autistic savants or geniuses, these extraordinary computational abilities come to the fore. We are on the threshold of a very exciting field which Fisher calls “quantum neuroscience” which could expand human potential like never before!
Quantum cognition: The possibility of processing with nuclear spins in the brain, Fisher, M. P. A. (2015). Annals of Physics, 362, 593–602.
Brains and Realities, Jay Alfred, 2006.
