With billions of dollars in flow Quantitative Statistics And countries are building Communication networks secured by quantum cryptographyThe The emergence of quantum information science It is becoming increasingly difficult to ignore.
This year’s Breakthrough Prize in Fundamental Physics is awarded to four pioneers who combined mathematics, computer science and physics for “foundational work in the field of quantum information.” The award is shared between Charles Bennett of IBM, Jill Brassard of the University of Montreal, David Deutsch of the University of Oxford and Peter Schur of the Massachusetts Institute of Technology.
“These four people contributed greatly to the emergence of quantum information theory,” says Nicholas Gisin, an experimental quantum physicist at the University of Geneva. “It’s nice to see these awards close to my heart.”
The Breakthrough Prize was co-founded by Israeli-Russian billionaire and physicist Yuri Milner in 2012, and has been generously backed by other emperors, including co-founders Mark Zuckerberg and Sergey Brin. Like Alfred Nobel, whose Nobel Prize-winning financial fortune stemmed from his invention of dynamite, Milner’s past financial ties to the Kremlin have come under scrutiny, particularly in light of Russia’s ongoing invasion of Ukraine. In previous interviews, Milner has emphasized his independence and his donations to Ukrainian refugees. A spokesperson noted Scientific American Milner moved to the United States in 2014 and has not returned to Russia since.
But recognition of quantum information science does not always come easily — or with such financial backing. In general, the field is a mixture of two theories: quantum mechanics, which describes the irrational behavior of the atomic and subatomic world, and information theory, which details the mathematical and physical limits of computation and communication. Its history is a chaotic story, with sporadic developments often overlooked by traditional scientific journals.
In 1968, Stephen Wisner, a graduate student at Columbia University, has developed a new method for encoding information using polarized photons. Among other things, Wiesner suggested that the inherently fragile nature of quantum states can be used to create anti-counterfeiting quantum money. Unable to publish many of his engaging theoretical ideas and an affinity for religion, Wiesner, who died last year, largely quit academia to become a construction worker in Israel.
Before Wiesner left Columbia, he passed on some of his ideas to another young researcher. “One of my roommates was Stephen Wisner, who started telling me about his ‘quantum money,’” Bennett recalls.[It] It struck me as interesting, but it doesn’t seem like the beginning of a whole new field.” In the late 1970s Bennett Brassard met, and the two began discussing Wisner money, which they imagined might require the unlikely task of trapping photons with mirrors to create a quantum banknote .
“Photons aren’t meant to stay — they travel,” Brassard says, explaining the thought process. “If they travel, what is more natural than communication?” Protocol Bennett and Brassard SuggestionCall BB84It will launch the field of quantum cryptography. Detailed later and popularized in Scientific American, BB84 allowed two parties to exchange messages with the utmost confidentiality. If a third party intrudes, they will leave indelible evidence of their interference – such as damaging a quantum wax seal.
As Bennett and Brassard developed quantum cryptography, another radical idea began to emerge: quantum computing. At a now famous meeting at the MIT Endicott House in Dedham, Massachusetts, in May 1981, physicist Richard Feynman Suggestion That a computer using quantum principles could solve impossible problems for a computer bound by the laws of classical physics. Although he did not attend the conference, Deutsch heard about the idea and was hooked. “I became more and more convinced of the connections between arithmetic and physics,” he says.
Chatting with Bennett later that year, Deutsch experienced a crucial emergence: then the dominant computational theory was based on faulty physics – Isaac Newton’s “classical” mechanics and Albert Einstein’s relativistic approach rather than a deeper quantum reality. So realistically, Deutsch says, “I thought I would rewrite the theory of computation, and base it on quantum theory rather than on classical theory.” “I basically wasn’t expecting anything new to come out of it. I expected it to be tougher.” I soon realize that it is a description A completely different kind of computer. Even if you achieved the same results, you got there through the principles of quantum mechanics.
Deutsch’s new theory provided a crucial link between quantum mechanics and information theory. “It made quantum mechanics available to me in my computer science language,” says Umesh Vasirani, a computer scientist at the University of California, Berkeley. Later, with Australian mathematician Richard Gwoza, Deutsch Suggested as a proof of principlethe first algorithm that would be much faster than classical algorithms – although it didn’t do anything practical.
But soon more useful applications appeared. In 1991, Arthur Eckert was a graduate student at Oxford University, Suggestion The new quantum cryptographic protocol, E91. This technique has attracted the attention of many physicists due to its elegance and practicality – as well as the fact that it has been published in a leading physics journal. “It’s a nice idea. It’s a bit surprising that Eckert isn’t part of this year’s list of Breakthrough Prize winners in Fundamental Physics, says Gizen.
Two years later, when Bennett, Brassard, Gwoza, computer science researcher Claude Crepeau and physicists Asher Perez and William Waters proposed Quantum teleportationPhysicists were taking notice. The new technology It would give one party the ability to pass information, such as the result of a coin flip, to another party via tangleQuantum correlation that can bind things like electrons. Despite the assertions of popular science fiction, this technology does not allow this Faster than light messages—but it has greatly expanded the possibilities of quantum communications in the real world. This is the most surprising idea,” Zhao Yang Luo said. A quantum physicist at the University of Science and Technology of China, who helped implement this technique from space.
Words like “revolution” are used excessively to describe advances in science, which are usually lagging and escalating. But in 1994 Shore quietly started one. While working at AT&T Bell Laboratories, he absorbed the conversations of Vazirani and Bennett. “I started thinking about useful things you can do with a quantum computer,” he says. “I thought it was a long shot. But it was a very interesting area. So I started working on it. I didn’t really tell anyone.”
Inspired by the success of other quantum algorithms in tasks that have been periodic or repetitive, Shore developed an algorithm that could split numbers into their prime factors (eg, 21 = 7 x 3) faster than any classical algorithm. The implications were immediately obvious: the initial analysis was the backbone of modern cryptography. Finally, quantum computers had a practical application that really changed the rules of the game. shore algorithm “I made it very clear that you have to give up everything” to work on quantum computing, Vasirani says.
Although Shore has found a powerful use case for a quantum computer, he hasn’t solved the toughest problem of how to build a computer—even in theory. The fragile quantum states that these devices can exploit to bypass classical computing have also made them vulnerable to errors. Moreover, error correction strategies for classical computers cannot be used in quantum computers. He did not hesitate at the 1995 Quantum Computing Conference in Turin, Italy, Sure bet other researchers That a quantum computer would consider a 500-digit number before a classical computer would. (Even with today’s classic supercomputers, taking 500 numbers into computing would probably take billions of years.) No one bet Shore, and some demanded a third option: that the sun would burn first.
There are two types of errors that plague quantum computers: bit errors and phase errors. These errors are like flipping a compass needle from north to south or east to west, respectively. Unfortunately, bit error correction exacerbates phase errors and vice versa. In other words, a more accurate north direction leads to a less accurate direction east or west. But later in 1995 shore Discover How to combine bit correction and phase correction A series of operations not unlike solving a Rubik’s cube without changing a completed aspect. Shor’s algorithm remains ineffective until quantum computers become more powerful (the highest analyzed number in the algorithm is 21, so conventional analysis remains on top—for now). But it still makes quantum computing possible, if not practical. “That’s when it all got real,” Brassard says.
All this work led to New perspectives on quantum mechanics and computing. For Deutsch, it inspired a more fundamental theory of “builders”—which, he says, describes “the set of all physical transformations.” Still others are unaware about the possibility of other profound insights emerging from the quantum realm. “Quantum mechanics is really weird, and I don’t think there would be any easy way to understand it,” Shore says. When asked if his work in quantum computing makes the nature of reality easier or more difficult to understand, he implicitly replied, “It certainly makes it more mysterious.”
What began as a hobby or an eclectic intellectual pursuit has now grown beyond many of the wildest perceptions of pioneers in the field. “We never thought it would ever become practical. Just thinking about these crazy ideas was so much fun,” Brassard says. “At one point, we decided we were serious, but people didn’t follow us. He was frustrated. Now that he’s been recognized to this extent it’s a lot of fun.”