1,306 research outputs found
Statistical Constraints on State Preparation for a Quantum Computer
Quantum computing algorithms require that the quantum register be initially
present in a superposition state. To achieve this, we consider the practical
problem of creating a coherent superposition state of several qubits. Owing to
considerations of quantum statistics, this requires that the entropy of the
system go down. This, in turn, has two practical implications: (i) the initial
state cannot be controlled; (ii) the temperature of the system must be reduced.
These factors, in addition to decoherence and sensitivity to errors, must be
considered in the implementation of quantum computers.Comment: 7 pages; the final published versio
Moving Observers in an Isotropic Universe
We show how the anisotropy resulting from the motion of an observer in an
isotropic universe may be determined by measurements. This provides a means to
identify inertial frames, yielding a simple resolution to the twins paradox of
relativity theory. We propose that isotropy is a requirement for a frame to be
inertial; this makes it possible to relate motion to the large scale structure
of the universe.Comment: 8 pages, 1 figure, with minor typographical correctio
A Three-Stage Quantum Cryptography Protocol
We present a three-stage quantum cryptographic protocol guaranteeing security
in which each party uses its own secret key. Unlike the BB84 protocol, where
the qubits are transmitted in only one direction and classical information
exchanged thereafter, the communication in the proposed protocol remains
quantum in each stage. A related system of key distribution is also described.Comment: 5 pages, 2 figure
Rule-Based Approach to Binocular Stereopsis
This research is motivated by a desire to integrate some of the diverse, yet complimentary, developments that have taken place during the past few years in the area of passive stereo vision. On the one hand, we have approaches based on matching zero-crossings along epipolar lines, and, on the other, people have proposed techniques that match directly higher level percepts, such as line elements and other geometrical forms. Our rule-based program is a modest attempt at integrating these different approaches into a single program. Such integration was made necessary by the fact that no single method by itself appears capable of generating usable range maps of a scene
Geometric phase and gauge theory structure in quantum computing
We discuss the presence of a geometrical phase in the evolution of a qubit
state and its gauge structure. The time evolution operator is found to be the
free energy operator, rather than the Hamiltonian operator.Comment: 5 pages, presented at Fifth International Workshop DICE2010:
Space-Time-Matter - current issues in quantum mechanics and beyond,
Castiglioncello (Tuscany), September 13-17, 201
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