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)
As is well known, operations on one particle of an Einstein-Podolsky-Rosen (EPR) pair cannot influence the marginal statistics of measurements on the other particle. We characterize the set of states accessible from an initial EPR state by one-particle operations and show that in a sense they allow two bits to be encoded reliably in one spin-2 particle: One… (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)
Based on an EPR pair of qubits and allowing asymptotically secure key distribution, a secure communication protocol is presented. Bob sends either of the EPR pair qubits to Alice. Alice receives the travel qubit. Then she can encode classical information by local unitary operations on this travel qubit. Alice send the qubit back to Bob. Bob can get Alice's… (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.