Description
Quantum mechanics is a mysterious world where a particle can exist in two states at once, or where a cat, named after Erwin Schrödinger, is alive and dead (or neither) as long as you don't look at it, because when you do, you definitely will be dead "I think I can safely say that no one understands quantum mechanics," legendary American physicist Richard Feynman said at the Cornell University Messenger Lectures in 1964. The following year he would win the Nobel Prize in physics for his work on quantum mechanics. . From quantum mechanics grew the search for quantum computers a few decades later, seeking to exploit the strange properties of nature at atomic levels. Such computers, in theory, would be several times faster than traditional computers.
In fact, it was none other than Feynman who, in 1981, had the idea of finding a computer simulation of physics. "The actual use would be with quantum mechanics...Nature isn't classical...and if you want to do a simulation of nature, you better do it in quantum mechanics, and damn, that's a wonderful problem, because it does not work". It doesn't seem so easy,” he said at a conference organized by the Massachusetts Institute of Technology and IBM.
Quantum computing is one of four areas for which topic centers will be set up at leading academic and national research and development institutes under the national quantum mission approved last week with a budget of Rs 6 billion. The other three areas are quantum communication, which seeks to transmit information that is difficult to hear; quantum sensing and metrology, or the use of quantum phenomena to make precise measurements; and quantum materials and devices, these being solid materials with exotic properties.
Quantum technology is an area where research still has miles to go, especially when it comes to building a "usable" quantum computer. However, some key milestones have been achieved, particularly in the last two decades.
Quantum mechanical potential Classical physics cannot explain much of the behavior of matter and energy at subatomic levels, but it can still explain much of the physical world. Quantum mechanics studies matter at the atomic and subatomic level, where the laws of classical physics no longer apply.
In Feynman's words, "things on a very small scale behave like nothing you have direct experience of." They don't behave like waves, they don't behave like particles, they don't behave like clouds, or billiard balls, or weights on springs, or anything you've ever seen.
This was stated by the physicist in a conference given at the California Institute of Technology. You can check it on the university website.
Quantum mechanics is about strange concepts: wave-particle duality, a property that allows matter and energy, such as light, to behave like a wave and a stream of particles; superposition, when an object exists in several possible states at the same time; and entanglement, when two or more particles or photons can exist in a "shared state", both behaving in the same way, even though they are far apart. The 2022 Nobel Prize in Physics was awarded to Alain Aspect, John Clauser, and Anton Zeilinger for their work on superposition.
While the benefits of quantum mechanics have attracted scientists for generations, they depend on the problem being solved, said Apoorva Patel, director of the Indian Institute of Science (IISc) Quantum Technology Initiative.
“Quantum physics was invented because certain physical phenomena could not be explained at all by classical theories. The practical benefit can be proven when such phenomena are at the center of the problems to be solved,” he said, citing the examples of overlap and entanglement, among others.
"Of course, classical theories explain many physical phenomena, and when they do, quantum technology will offer little advantage in addressing them," Patel said.
The challenge is that quantum dynamics is very brittle. “Environmental disturbances rapidly destroy quantum signals. Therefore, quantum effects can only be observed in highly protected and cooperative environments. They do not survive in hostile situations. The need to build a carefully protected framework is what makes quantum technology expensive,” Patel said.
As such, there will be many situations where conventional technology will be more robust, cheaper, and effective. Therefore, quantum technology will only be useful in "special purpose devices," he said.
“A deep understanding of quantum physics is needed to understand what such devices would look like. The rest is just hype," Patel said.
"Special-purpose devices can do many useful things. An obvious answer is that the first rewards will come from the development of high-precision sensors and measuring instruments, which will undoubtedly bring many benefits to society. The real challenges lie in the "design. of such systems and not in their use. That is where you have to make the investment. Whether the government and the industry pay attention to it or not, is another story," he said.
High-precision sensors and measuring instruments would enter the domain of metrology and quantum sensing. These sensors are vital to devices such as atomic clocks, platforms used in the manufacture of quantum computers, and various scientific fields that require high precision.
Quantum computing A quantum computer would be superior to classical computers in several aspects, the main ones being speed of processing and stronger encryption of information. A typical computer stores information in terms of bits, which come in combinations of 0 and 1. A quantum computer, on the other hand, would store information in quantum bits, or qubits. A qubit can be 0 and 1 at the same time, and since this information can probabilistically exist in multiple forms simultaneously, the information stored increases exponentially with the number of qubits.
In quantum communication, the nature of cryptography would make it impossible to eavesdrop without being detected. One widely studied method is to transmit a quantum "key" via a series of photons. If someone eavesdropped on the communication, some of the key's properties would change, just as Schrödinger's cat would have died when watched, and thus the sender of the information would know that there was a breach.
The challenges remain with the brittleness of quantum states and the design of such systems. At the heart of a quantum computer are its qubits, created as a lattice of atoms of an appropriate element or isotope. These are levitating in free space in a vacuum environment. Storing and manipulating information in this exotic way requires sophisticated control of the underlying materials, Princeton University scientists said in a 2021 Science article, calling on materials scientists to realize the challenge of developing hardware for data storage. quantum computing.
Progress so far Although a usable quantum computer is still a long way off, the search has progressed since Feynman's observations in 1981.
In 1985, Oxford researcher David Deutsch published a theoretical paper describing a universal quantum computer. What aroused the most interest, however, was an algorithm proposed in 1994 by Massachusetts Institute of Technology professor Peter Shor, then working for the US telecommunications giant AT&T.
Shor proposed a method that uses entanglement and superposition of qubits to find the prime factors of an integer. This was potentially important because finding factors of large numbers is so difficult that many encryption systems take advantage of this difficulty. Shor's idea led to a storm of research, but what he came up with in theory proved difficult to achieve.
"No other algorithm has been found to rival Shor's potential. Despite the disappointment, the momentum has not been lost and the field has branched in different directions," Nature observed in an editorial, "40 years of computing quantum", in January 2022. .
In the current century, universities and companies have made new progress. According to the University of Washington, the record for the most qubits currently stands at 72, on a chip developed by Google. In 2017, Microsoft released Q#, a language for quantum algorithms. And in January 2019, IBM announced one of the first commercial quantum computers.
Also in 2019, Google announced that its collaborators at the University of California, Santa Barbara had achieved quantum supremacy, the stage where a quantum computer performs tasks that a classical computer cannot. University researchers claimed to have developed a processor that took 200 seconds to perform a calculation that would have taken a typical computer 10,000 years. The claim, however, was disputed by IBM.
Most existing quantum computers use metal-insulator-metal sandwiches that are transformed into superconducting qubits by shrinking them at extremely low temperatures, according to a paper published on the US Department of Energy website. But, "scientists that routinely use quantum computers to answer scientific questions are still a long way off," he added.
Kabir Firaque, editor of Puzzles, is the author of the weekly column Problemática. A journalist for three decades, he also writes about science and mathematics. ...See details
