A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of both particles and waves, and quantum computing leverages this behavior using specialized hardware. Classical physics cannot explain the operation of these quantum devices, and a scalable quantum computer could perform some calculations exponentially faster than any modern "classical" computer. In particular, a large-scale quantum computer could break widely used encryption schemes and aid physicists in performing physical simulations; however, the current state of the art is largely experimental and impractical, with several obstacles to useful applications.
Quantum information is the information of the state of a quantum system. It is the basic entity of study in quantum information theory, and can be manipulated using quantum information processing techniques. Quantum information refers to both the technical definition in terms of Von Neumann entropy and the general computational term.
Peter Williston Shor is an American professor of applied mathematics at MIT. He is known for his work on quantum computation, in particular for devising Shor's algorithm, a quantum algorithm for factoring exponentially faster than the best currently-known algorithm running on a classical computer.
In logic circuits, the Toffoli gate, also known as the CCNOT gate (“controlled-controlled-not”), invented by Tommaso Toffoli, is a CNOT gate with two control qubits and one target qubit. That is, the target qubit will be inverted if the first and second qubits are both 1. It is a universal reversible logic gate, which means that any classical reversible circuit can be constructed from Toffoli gates. Formally, we describe the Toffoli gate with the following truth table and matrix:
Rolf William Landauer was a German-American physicist who made important contributions in diverse areas of the thermodynamics of information processing, condensed matter physics, and the conductivity of disordered media. Born in Germany, he emigrated to the U.S. in 1938, obtained a Ph.D. in physics from Harvard in 1950, and then spent most of his career at IBM.
Artur Konrad Ekert is a British-Polish professor of quantum physics at the Mathematical Institute, University of Oxford, professorial fellow in quantum physics and cryptography at Merton College, Oxford, Lee Kong Chian Centennial Professor at the National University of Singapore and the founding director of the Centre for Quantum Technologies (CQT). His research interests extend over most aspects of information processing in quantum-mechanical systems, with a focus on quantum communication and quantum computation. He is best known as one of the pioneers of quantum cryptography.
Reversible computing is any model of computation where the computational process, to some extent, is time-reversible. In a model of computation that uses deterministic transitions from one state of the abstract machine to another, a necessary condition for reversibility is that the relation of the mapping from states to their successors must be one-to-one. Reversible computing is a form of unconventional computing.
Gilles Brassard, is a faculty member of the Université de Montréal, where he has been a Full Professor since 1988 and Canada Research Chair since 2001.
Claude Crépeau is a professor in the School of Computer Science at McGill University. Ηe was born in Montreal, Quebec, Canada, in 1962. He received a master's degree from the Université de Montréal in 1986, and obtained his Ph.D. in Computer Science from MIT in 1990, working in the field of cryptography with Silvio Micali as his Ph.D. advisor and Gilles Brassard as his M.Sc advisor. He spent two years as a Postdoctoral Fellow at Université d'Orsay, and was a CNRS researcher at École Normale Supérieure from 1992 to 1995. He was appointed associate professor at Université de Montréal in 1995, and has been a faculty member at McGill University since 1998. He was a member of the Canadian Institute for Advanced Research program on Quantum Information Processing from 2002 to 2012.
Landauer's principle is a physical principle pertaining to the lower theoretical limit of energy consumption of computation. It holds that an irreversible change in information stored in a computer, such as merging two computational paths, dissipates a minimum amount of heat to its surroundings.
Dorit Aharonov is an Israeli computer scientist specializing in quantum computing.
BB84 is a quantum key distribution scheme developed by Charles Bennett and Gilles Brassard in 1984. It is the first quantum cryptography protocol. The protocol is provably secure assuming a perfect implementation, relying on two conditions: (1) the quantum property that information gain is only possible at the expense of disturbing the signal if the two states one is trying to distinguish are not orthogonal ; and (2) the existence of an authenticated public classical channel. It is usually explained as a method of securely communicating a private key from one party to another for use in one-time pad encryption. The proof of BB84 depends on a perfect implementation. Side channel attacks exist, taking advantage of non-quantum sources of information. Since this information is non-quantum, it can be intercepted without measuring or cloning quantum particles.
Nathaniel David Mermin is a solid-state physicist at Cornell University best known for the eponymous Hohenberg–Mermin–Wagner theorem, his application of the term "boojum" to superfluidity, his textbook with Neil Ashcroft on solid-state physics, and for contributions to the foundations of quantum mechanics and quantum information science.
John A. Smolin is an American physicist and Fellow of the American Physical Society at IBM's Thomas J. Watson Research Center.
Richard Erwin Cleve is a Canadian professor of computer science at the David R. Cheriton School of Computer Science at the University of Waterloo, where he holds the Institute for Quantum Computing Chair in quantum computing, and an associate member of the Perimeter Institute for Theoretical Physics.
Stephen J. Wiesner was an American-Israeli research physicist, inventor and construction laborer. As a graduate student at Columbia University in New York in the late 1960s and early 1970s, he discovered several of the most important ideas in quantum information theory, including quantum money, quantum multiplexing and superdense coding. Although this work remained unpublished for over a decade, it circulated widely enough in manuscript form to stimulate the emergence of quantum information science in the 1980s and 1990s.
Norman H. Margolus is a Canadian-American physicist and computer scientist, known for his work on cellular automata and reversible computing. He is a research affiliate with the Computer Science and Artificial Intelligence Laboratory at the Massachusetts Institute of Technology.
Sandu Popescu is a Romanian-British physicist working in the foundations of quantum mechanics and quantum information.
Paul Anthony Benioff was an American physicist who helped pioneer the field of quantum computing. Benioff was best known for his research in quantum information theory during the 1970s and 80s that demonstrated the theoretical possibility of quantum computers by describing the first quantum mechanical model of a computer. In this work, Benioff showed that a computer could operate under the laws of quantum mechanics by describing a Schrödinger equation description of Turing machines. Benioff's body of work in quantum information theory encompassed quantum computers, quantum robots, and the relationship between foundations in logic, math, and physics.
Aditi Sen De is an Indian scientist, a professor in quantum information and computation group at the Harish-Chandra Research Institute, Prayagraj. She was born on 1 October 1974 in Kolkata, India. She is known for her research on quantum information and computation, quantum communication including quantum cryptography, quantum optics and many-body physics. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded her the Shanti Swarup Bhatnagar Prize for Science and Technology for her contributions to physical sciences in 2018. She is the first female physicist to be given this honour. In 2022, she was elected as a member of Indian Academy of Sciences and Indian National Science Academy.
