The 2022 Nobel Prize in Physics have just been announced. Three laureates – Alain Aspect (France), John Clauser (US) and Anton Zeilinger (Austria) will share the prize for their groundbreaking experimental work confirming the existence of quantum entanglement, the bizarre phenomenon in which two widely separated particles can share information despite having no conceivable way of communicating. Their results have cleared the way for the development of new technologies such as quantum computing, quantum networks and cryptography based on quantum information.
Great work and a well-deserved accolade for the trio! You can read more about their achievements on the Nobel Prize website at www.nobelprize.org.
Meanwhile, let us not forget that there is another “Nobel Prize” in physics that (to me) is equally prestigious and in fact, worth more in monetary value, and that is the Breakthrough Prize, awarded annually in the Life Sciences, Fundamental Physics and Mathematics. The Breakthrough Prize is founded by Sergey Brin, Priscilla Chan and Mark Zuckerberg, Julia and Yuri Milner, and Anne Wojcicki and have been sponsored by foundations established by them.
This year, the Breakthrough Prize in Fundamental Physics (awarded for 2023) goes to four scientists who have made seminal contributions to the development of quantum information theory (QIT). The recipients are: Charles Bennett (IBM Thomas J. Watson Center), Gilles Brassard (University of Montreal, Canada), David Deutsch (Oxford University), and Peter Shor (MIT). Their work has laid the theoretical foundation for a whole range of quantum information applications, including the ones mentioned earlier.
QIT is the study of how computational tasks can be accomplished using quantum computers rather than classical computers, thus solving complex tasks which are impossible or intractable in the classical realm.
The Work of David Deutsch
The idea of using quantum mechanical laws for computation was proposed in 1982 by the eminent American physicist and Nobel laureate, Richard Feynman. But it was David Deutsche at Britain’s Oxford University who laid the conceptual foundation for QIT by showing that computers that operate on quantum principles such as superimposition and entanglement can carry out some calculations much faster and more efficiently than those that obey classical laws. Thus was born the idea of quantum computers that rely on quantum bits (qubits) instead of the binary bits of classical computers.
The Work of Peter Shor
The scientific community was initially skeptical of whether the bizarre world of quantum mechanics could be of any significant practical use. Said William Wootters, a quantum physicist at Williams College: “I remember conversations in the early 1990s in which people would argue about whether quantum computers would ever be able to do anything really useful. Then suddenly Peter Shor devised a quantum algorithm that could indeed do something eminently useful.”
In 1995 Shor (who is now at MIT) developed a algorithm that could factorize (i.e., decompose) large integers into products of prime numbers much faster than any known classical algorithm. Factorizing large numbers is the key to data encryption, so methods which can factorize such numbers much more efficiently are of tremendous value in the modern digital world. Practically all current data encryption are implemented using classical computation. The problem is that in classical computation, the time it takes to factorize a large number increases exponentially as the number gets larger. Shor proved that his algorithm, based on quantum principles, could achieve similar tasks at a fraction of the time taken by classical computers. As Wootters put it, Shor’s quantum algorithm made quantum information theory “eminently useful.”
The Work of Charles Bennett and Gilles Brassard
Data encryption is also the field of research pursued by Bennett and Brassard. In a 1984 paper, the pair introduced a method in which information could be encoded in qubits and sent between two parties such that the information could not be read by an eavesdropper without it being detected. Their quantum cryptographic scheme relies on a strange property in quantum mechanics called entangling, meaning that the properties qubits are tied to each other, no matter how far apart they are separated. The Bennett-Brassard protocol and similar quantum encryption schemes have now been used to secure data transmission in optical networks and via satellite, over thousands of kilometers. For more details, see note 1 in the footnotes.
Bennett and Brassard also showed how entanglement may be harnessed for “quantum teleportation,” whereby the state of one qubit is broadcast to another distant one while the original state is destroyed.” See note 2 in the footnotes.
Summing Up
What do the laureates of this year’s award have to say about their own work and those of the co-winners? “I am really gratified by this award because it recognizes the field of quantum information and computation,” says Shor. Deutsch echoes the sentiment: “I’m glad that [quantum information] is now officially regarded as fundamental physics rather than as philosophy, mathematics, computer science, or engineering.”
This post is adapted from the American Physical Society article by Phillip Ball, entitled “Breakthrough Prize for the Physics of Quantum Information…and of Cells”, September 27, 2022.
Further study
[1] see Focus: Intercontinental, Quantum-Encrypted Messaging and Video)