quantum supremacy

“ Revolution is coming. In 2019 and 2020, two bombshells rocked the world of science. Two groups announced that they had achieved quantum supremacy, the fabled point at which a radically new type of computer, called a quantum computer, could decisively outperform an ordinary digital supercomputer on specific tasks. This heralded an upheaval that can change the entire computing landscape and overturn every aspect of our daily life. ”

“ pharmaceutical companies are also watching developments in this field intently, realising that quantum computers may be able to simulate complex chemical and biological processes that are far beyond the capability of digital computers. Huge facilities devoted to testing millions of drugs may one day be replaced by “virtual laboratories” that test drugs in cyberspace. ”

“ Even the Large Hadron Collider outside Geneva, Switzerland, the biggest science machine in the world, which slams protons together at 14 trillion electron volts to re-create the conditions of the early universe, now uses quantum computers to help sift through mountains of data. In one second, they can analise up to one trillion bytes generated by about one billion particle collisions. Perhaps one day quantum computers will unravel the secrets of the creation of the universe. ”

“ However, Nobel laureate Richard Feynman in 1959 saw a different approach to digital information. In a prophetic, pathbreaking essay titled “There’s Plenty of Room at the Bottom” and subsequent articles, he asked: Why not replace this sequence of 0s and 1s with sates of atoms, making an atomic computer? Why not replace transistors with the smallest possible object, the atom? ”

“ Digital bits can only carry one bit of information at a time, which limits their power, but qubits, or quantum bits, have almost unlimited lower. The fact that, at the atomic level, objects can exist simultaneously in multiple states is called superposition. ”

“ The problem facing quantum computers was also foreseen by Richard Feynman when he first proposed the concept. In order for quantum computers to work, atoms have to be arranged precisely so that they vibrate in unison. This is called coherence. But atoms are incredibly small and sensitive objects. The smallest impurity or disturbance from the outside world can cause this array of atoms to fall out of coherence, ruining the entire calculation. This fragility is the main problem facing quantum computers. ”

“ One day, Plank tried to derive the Rayleigh-Jeans catastrophe for his physics class, but with a strange, novel method. He was tried of doing it in the same old-fashioned way, so, purely pedagogical reasons, he made a bizarre assumption. He supposed that the energy emitted from an atom could only be found in tiny discrete packs of energy, which are called quanta. This was heresy, because Newton’s equations stated that energy should be continuous, not in packets. But when Planck postulated that the energy occurred in packets of a certain size, he found precisely the correct curve linking frequency and energy for light. This was a discovery of ages. ”

“ Although his theory indisputably fit the experimental data and opened up an entirely new branch of physics, he was hounded for years by stubborn, die-hard believers in the classical, Newtonian idea. Describing this blizzard of opposition, Plank wrote: “A new scientific truth does not triumph by convincing its opponents and making them see the light. but rather because its opponents eventually die, and a new generation grows up that is familiar with it.” But no matter how fierce the opposition was, more and more evidence began to pile up confirming the quantum theory. It was indisputably correct. ”

“ In 1930, Einstein had had enough. At the Sixth Solvay Conference in Brussels, Einstein decided he would go head-to-head and challenge Niels Bohr, the leading proponent of quantum mechanics. … “It was the greatest debate in intellectual history that I know about. In thirty years, I never heard of a debate between two greater men over a longer period of time on a deeper issue with deeper consequences for understanding this strange world of ours.” ”

“ He was famous for saying that the goal of every physicist “is to prove yourself wrong as soon as possible.” In other words, swallow your pride and admit that what you are doing may be a dead end, and prove it as soon as possible so you can move on the next idea. (As a research physicist, I actually think about this statement often. At some point physicists may have to admit that maybe their pet idea is wrong, and that they should quickly try a new approach.) ”

“ So Feynman rewrote the quantum theory in terms of the principle of least action. In this view, subatomic particles “sniff out” all possible paths. On each path he put a factor related to the action and Planck’s constant. Then he summed or integrated over all possible paths. This is now called the path integral approach, because you are adding up contributions from all the paths an object can take. ”

“ So how does Mother Nature solve the problem of decoherence, the most difficult problem in quantum computers, to enable photosynthesis at room temperature? By summing over all paths. As Feynman showed, electrons can “sniff” out all possible paths to do their miraculous work. In other words, photosynthesis, and hence life itself, may be a by-product of Feynman’s path integral approach. ”

“ But this “collapsing” has haunted quantum physicists for the past century. This process of “collapsing” the wave seems so alien, so contrived and artificial, yet it is crucial process that allows one to leave the quantum world and enter our macroscopic world. Why does it snap to attention just when we decide to look at it? It is the bridge between the micro- and macroworlds, but it is a bridge with huge philosophical holes in it. ”

“ Perhaps the most outrageous of these proposals was made in 1956 by graduate student Hugh Everett. We recall that the quantum theory can be summarized in roughy four broad principles. The last one is the sticking point, where we “collapse” the wave function to decide what state the system is in. Everett’s proposal was daring and controversial: his theory says simply to drop the last statement that says the wave “collapses” so it never does at all. Each possible solution continues to exit in its own reality, producing, as the theory is known, “many worlds.” ”

“ The Road Not Taken by Robert Frost Two roads diverged in a yellow wood, And sorry I could not travel both And be one traveler, long I stood And looked down one as far as I could To where it bent in the undergrowth. … I shall be telling this with a sigh Somewhere ages and ages hence: Two roads diverged in a wood, and I —— I took the one less traveled by, And that has made all the difference. ”

“ The key advantage of a quantum computer is time. Although both classical and quantum computers can perform certain tasks, the time it takes classical computers to crack a difficult problem may take it totally impractical. ”

“ In the future, top secret messages may be sent on a separate internet channel carried by laser beams, not electrical cables. Laser beams are polarized, meaning that the waves vibrate in only one plane. When a criminal tries ti tap into the laser beams, this changes the direction of polarization of the laser, which is immediately detected by a monitor. In this way, you know, by the laws of the quantum theory, that some one has tapped into your communication. ”

“ This problem of security is also leading to a new technology called quantum key distribution, which transfers encryption keys using entangled qubits, so that one can detect immediately if someone is hacking into your network. Already, Japan’s Toshiba company has predicted that QKD may generate up to $3 billion in revenue by the end of this decade. ”