A quantum computer is a computer that takes advantage of quantum mechanical phenomena.
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.
Quantum teleportation is a technique for transferring quantum information from a sender at one location to a receiver some distance away. While teleportation is commonly portrayed in science fiction as a means to transfer physical objects from one location to the next, quantum teleportation only transfers quantum information. The sender does not have to know the particular quantum state being transferred. Moreover, the location of the recipient can be unknown, but to complete the quantum teleportation, classical information needs to be sent from sender to receiver. Because classical information needs to be sent, quantum teleportation cannot occur faster than the speed of light.
Quantum key distribution (QKD) is a secure communication method that implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only to them, which then can be used to encrypt and decrypt messages. The process of quantum key distribution is not to be confused with quantum cryptography, as it is the best-known example of a quantum-cryptographic task.
Bell's theorem is a term encompassing a number of closely related results in physics, all of which determine that quantum mechanics is incompatible with local hidden-variable theories, given some basic assumptions about the nature of measurement. "Local" here refers to the principle of locality, the idea that a particle can only be influenced by its immediate surroundings, and that interactions mediated by physical fields cannot propagate faster than the speed of light. "Hidden variables" are putative properties of quantum particles that are not included in quantum theory but nevertheless affect the outcome of experiments. In the words of physicist John Stewart Bell, for whom this family of results is named, "If [a hidden-variable theory] is local it will not agree with quantum mechanics, and if it agrees with quantum mechanics it will not be local."
Alice and Bob are fictional characters commonly used as placeholders in discussions about cryptographic systems and protocols, and in other science and engineering literature where there are several participants in a thought experiment. The Alice and Bob characters were invented by Ron Rivest, Adi Shamir, and Leonard Adleman in their 1978 paper "A Method for Obtaining Digital Signatures and Public-key Cryptosystems". Subsequently, they have become common archetypes in many scientific and engineering fields, such as quantum cryptography, game theory and physics. As the use of Alice and Bob became more widespread, additional characters were added, sometimes each with a particular meaning. These characters do not have to refer to people; they refer to generic agents which might be different computers or even different programs running on a single computer.
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.
Conjugate coding is a cryptographic tool, introduced by Stephen Wiesner in the late 1960s. It is part of the two applications Wiesner described for quantum coding, along with a method for creating fraud-proof banking notes. The application that the concept was based on was a method of transmitting multiple messages in such a way that reading one destroys the others. This is called quantum multiplexing and it uses photons polarized in conjugate bases as "qubits" to pass information. Conjugate coding also is a simple extension of a random number generator.
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.
In quantum information theory, the channel-state duality refers to the correspondence between quantum channels and quantum states. Phrased differently, the duality is the isomorphism between completely positive maps (channels) from A to Cn×n, where A is a C*-algebra and Cn×n denotes the n×n complex entries, and positive linear functionals (states) on the tensor product
Nathaniel David Mermin is a solid-state physicist at Cornell University best known for the eponymous 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.
A quantum money scheme is a quantum cryptographic protocol that creates and verifies banknotes that are resistant to forgery. It is based on the principle that quantum states cannot be perfectly duplicated, making it impossible to forge quantum money by including quantum systems in its design.
Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best known example of quantum cryptography is quantum key distribution which offers an information-theoretically secure solution to the key exchange problem. The advantage of quantum cryptography lies in the fact that it allows the completion of various cryptographic tasks that are proven or conjectured to be impossible using only classical communication. For example, it is impossible to copy data encoded in a quantum state. If one attempts to read the encoded data, the quantum state will be changed due to wave function collapse. This could be used to detect eavesdropping in quantum key distribution (QKD).
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.
MSZ96 is a quantum key distribution protocol which allows a cryptographic key bit to be encoded using four nonorthogonal quantum states described by non-commuting quadrature phase amplitudes of a weak optical field, without photon polarization or entangled photons. It is named afet Yi Mu, Jessica Seberry; Yuliang Zheng.
Consider two remote players, connected by a channel, that don't trust each other. The problem of them agreeing on a random bit by exchanging messages over this channel, without relying on any trusted third party, is called the coin flipping problem in cryptography. Quantum coin flipping uses the principles of quantum mechanics to encrypt messages for secure communication. It is a cryptographic primitive which can be used to construct more complex and useful cryptographic protocols, e.g. Quantum Byzantine agreement.
Quantum Experiment using Satellite Technology launched in 2017 by Raman Research Institute in February 2021 demonstrated Quantum communication for 50 m apart and on 19 March 2021 for 300 m apart inline of sight in Space Applications Centre in coordination with Indian Space Research Organisation ,Indian Institute of Science and Tata Institute of Fundamental Research,. India 's first project on satellite based long distance Quantum communication,
