Today we will talk about an extremely important development that took place in the science of quantum computing. The history of this is intertwined in many ways with the history of the industrial fabric itself. One of the most important patents in the field of weaving was the “Jacquard machine” in 1804. It was a set of components that allowed a mechanical loom to weave any pattern from a set of threads. It was enough to feed the loom with a series of perforated cards that coded the weave, without making changing the weave any more complicated than simply changing the set of cards. Although not the only one, it was a fundamental development in the industrialization of textiles, which in turn was an important milestone in the industrial revolution.
We find the same punch card logic in a new role at the dawn of the computer age. With an identical philosophy, a program was written as a series of punched cards, with holes and untouchable dots that encoded the program as a series of “1”s and “0s,” ie the common language among all computers. However, the connection between the fabric and computers does not stop there. Early versions of computer memory consisted of metal elements strung together through a grid of wires. They didn’t just look like fabric, they were: NASA had hired former textile workers through Raytheon to use their expertise to “knit” the memory used in the Apollo vehicles. [α, β].
The next step in computing is quantum computers. By using extremely well-insulated and very small systems of individuals for the computation, we can “choreograph” a program so that all paths to wrong answers cancel each other out and only the correct answer remains. We know how to do those “choreographies” so far for a few specific categories of problems. But in them, quantum computers easily solve problems that a supercomputer wouldn’t solve even if it had been running continuously since the beginning of our universe. It is no coincidence that a significant part of cryptographic protocols is based precisely on this type of problem (unsolvable for classical computers), and there is great scientific interest. [γ] and economic interest in them.
The reason why quantum computers are not part of everyday life is precisely the extreme sensitivity of their arrangements: if “quantum bits” slightly interact with the environment, they lose all their useful properties. For this reason, experimental quantum computers to date can maintain their operation for short periods of time and consume a significant part of their capabilities to discover and correct the resulting errors. This is not helped at all by the fact that in the microcosm the particles are identical. If we have two particles in front of us, we close our eyes and someone changes position twice, it is impossible to understand. Using an analogy with an empty knitting machine, if we leave the room and re-enter it will be impossible to tell if it worked while we were gone and simply went back to its original position.
At this point, two very important publications from the Google team arrive [δ] and the company Quantinum [ε]. Both succeeded by using a special form of “virtual particles” that appears when we limit quantum bits to a level called “non-abelian anions.” Using the previous analogy, it is like feeding thread to the machine: if we leave the room and come back, we can tell if it has moved or not by seeing if it has produced fabric. According to one interpretation, these particles remain identical to each other, but if they move they produce “knots” in space-time.
This entanglement can be measured, opening a new avenue for efficient error correction of quantum computers. Such a development, using a kind of virtual particles that until recently was a mathematical construct, is in itself a great technical and theoretical milestone. Furthermore, it broadens our options for building real quantum computers, the impact of which will be decisive in a variety of fields, from cutting-edge medical research to cryptography and financial management.
[α] Fildes, J. (2009, July 15). Weaving the way to the Moon. BBC News. http://news.bbc.co.uk/1/hi/8148730.stm
[β] Visual Introduction to the Apollo Guidance Computer, Part 3: Fabrication of the Apollo Guidance Computer. AGC: Visual Introduction to the Apollo Guidance Computer, Part 3. http://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/visual3.htm
[γ] Saida, D., Hidaka, M., Imafuku, K., & Yamanashi, Y. (2022). Quantum annealing factorization using superconducting flow qubits implementing a Hamiltonian multiplier. Scientific Reports, 12(1). https://doi.org/10.1038/s41598-022-17867-9
[δ] Andersen, T.I., Lensky, Y.D., Kechedzhi, K., Drozdov, I.K., Bengtsson, A., Hong, S., Morvan, A., Mi, X., Opremcak, A., Acharya, R., Allen, R. . ., Ansmann, M., Arute, F., Arya, K., Asfaw, A., Atalaya, J., Babbush, R., Bacon, D., Bardin, JC, … Roushan, P. (2023). Non-abelian braiding of graph vertices on a superconducting processor. Nature. https://doi.org/10.1038/s41586-023-05954-4
[ε] Iqbal, M., Tantivasadakarn, N., Verresen, R., Campbell, SL, Dreiling, JM, Figgatt, C., Gaebler, JP, Johansen, J., Mills, M., Moses, SA, Pino, JM, Ransford, A., Rowe, M., Siegfried, P., Stutz, RP, Foss-Feig, M., Vishwanath, A., and Dreyer, H. (May 5, 2023). Creation of non-abelian topological ordering and anyons in a trapped ion processor. arXiv.org. https://arxiv.org/abs/2305.03766
Hector-Xavier Delastik is Applied Physicist, YD Department of Medicine, University of Patras