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restrictions on measurement related to the uncertainty principal. Two concrete examples and some general results are given. The uncertainty principle imposes restrictions on the capacity of certain types of communication channels. This paper will show that in compensation for this "quantum noise", quantum mechanics allows us novel forms of coding without… (More)
We suggest that quantum computers can solve quantum many-body problems that are impracticable to solve on a classical computer. The classical many-body problem has been largely solved by the classical computer. For example the position of the planets in the solar system can now be predicted with an accuracy as great as the accuracy of the observations. On… (More)
We present a two-party protocol for " quantum gambling, " a new task closely related to coin tossing. The protocol allows two remote parties to play a gambling game such that in a certain limit it becomes a fair game. No unconditionally secure classical method is known to accomplish this task. Quantum cryptography is a field which combines quantum theory… (More)
It is shown that a simplified version of the error correction code recently suggested by Shor ͓Phys. Rev. A 52, R2493 ͑1995͔͒ exhibits manifestation of the quantum Zeno effect. Thus, under certain conditions, protection of an unknown quantum state is achieved. Error prevention procedures based on four-particle and two-particle encoding are proposed and it… (More)
This paper describes the design and operation of Two-&amp;-Two, a program for finding pairs of documents which form a bridge between two inputs. Two-&amp;-Two is built on top of Finder, a retrieval system based on relevance feedback that operates on the massively parallel Connection Machine System.
1. Introduction Broadly speaking, cryptography is the problem of doing communication or computation involving two or more parties who may not trust one another. The best known cryptographic problem is the transmission of secret messages. Suppose wish to communicate in secret. For example, you may wish to give your credit card number to a merchant in… (More)
This work surveys the recent results in the theory of cryptography in a quantum computing model. Under the assumption that a quantum computer is built, we consider such notions as encryption and authentication of quantum data, and compare them with their classical counterparts. Many surprizes are unraveled. Once again, these results show how strikingly… (More)