8. Quantum advantage defined, almost-achieved and taken another shot at.
By: Kuba Pilch
Tags: Quantum Advantage, Science, Quantum Computing, Research, Kubareads

Today I am exited to recommend three papers in quantum computing, the field fuelling my own research flame. While two of them are not peer-reviewed, they could not really have been — the first is a transcript of a now-famous talk, and is widely acknowledged by the scientific community, ant the second is an introduction to a particular architecture of a computer coming from one of the new competitors in the field. I also realize the specificity of this content may not sparks everyone’s interest, but I believe there is something to learn for everybody here. I invite you to take a broader look at the story told by this research, and the breadth and depth it covers in spite of being focused on such a narrow field of science and engineering.

Quantum computing and the entanglement frontier — medium-easy read. (I do appreciate that many readers may find this medium-hard, or even hard, given some terms and concepts presented. However, the paper is not directed at specialists and an engaged reader can definitely understand and take a lot out of it.) A classic talk by John Preskill from the 25th Solvay Conference on Physics. The author starts by an introduction into the field; why should we care about quantum computing and is it at all practically possible? He then goes on to describe some of the mathematics and many of the core concepts behind it, including examples of cornerstone algorithms, error-correction and quantum bit implementations. The focus of the paper is around a terribly named, though important, concept of q̶u̶a̶n̶t̶u̶m̶ ̶s̶u̶p̶r̶e̶m̶a̶c̶y̶ quantum advantage (the original name has obviously horrible connotations, and is by now widely replaced within the community), that is: moment when quantum computers are able to run computations practically unachievable by classical machines. (Note: the requirement is for the computation to be practically impossible classically, not useful in any way, making this an important and remarkable but not groundbreaking milestone.) A good read, with wealth of terrific references and an interesting introduction into the field.

Quantum supremacy using a programmable superconducting processor — medium-hard read. Paper by Google researchers reporting they have achieved the goal described by Preskill 8 years earlier. (Unfortunately they decided to go with the horrible name, which is a shame.) This peer-reviewed article describes the architecture of the Sycamore processor, which 53 out of 54 qubits were used to run a pseudo-random distribution sampling algorithm and return results in just a few minutes. The authors estimated that the same computation would take at least 10 thousand years on any classical supercomputers. There is a caveat though: IBM researchers commented that the original paper, while brilliant, misestimated the need for classical resources and the problem could be in fact solved classically in a few days (basically: Arute et al. did not take classical operations using disk storage into account.) Having said that, the paper is overall a very good read, describing the hardware itself, error-rates, the algorithm and the experiment in great detail. Definitely worth a read, especially to get a better grip on the coming paradigm that will hopefully transform the face of computing one more time.

Demonstration of the QCCD trapped-ion quantum computer architecture — medium-hard read.This is a very specific paper, and I do not really plan on sharing many ones of its kind. This is an article describing a newly proposed hardware architecture for a scalable quantum computer by Honeywell. By its very nature it is not peer reviewed — the results will be seen once the company unveils their actual machine. Pino et al. bring us a novel approach to a known trapped-ion quantum computing architecture from a somehow unexpected player, and the results are very promising indeed. I believe it is an interesting and important read for people following the field. However, I mainly wanted to share it to complete the other two reads and show the breadth of research necessary to reach meaningful conclusions. From theoretical backgrounds, through countless architecture proposals, to experiment designs and still newer hardware approaches — it is mind-blowing to see how many people dedicate their lives to contribute small bricks of science that, through successes and failures, hopefully add up to a better understanding of our world and enable us to exploit some of its features for good.