288,530 research outputs found
Quantum Theory of Probability and Decisions
The probabilistic predictions of quantum theory are conventionally obtained
from a special probabilistic axiom. But that is unnecessary because all the
practical consequences of such predictions follow from the remaining,
non-probabilistic, axioms of quantum theory, together with the
non-probabilistic part of classical decision theory
Requirement for quantum computation
We identify "proper quantum computation" with computational processes that
cannot be efficiently simulated on a classical computer. For optical quantum
computation, we establish "no-go" theorems for classes of quantum optical
experiments that cannot yield proper quantum computation, and we identify
requirements for optical proper quantum computation that correspond to
violations of assumptions underpinning the no-go theorems.Comment: 11 pages, no figure
Continuous-variable blind quantum computation
Blind quantum computation is a secure delegated quantum computing protocol
where Alice who does not have sufficient quantum technology at her disposal
delegates her computation to Bob who has a fully-fledged quantum computer in
such a way that Bob cannot learn anything about Alice's input, output, and
algorithm. Protocols of blind quantum computation have been proposed for
several qubit measurement-based computation models, such as the graph state
model, the Affleck-Kennedy-Lieb-Tasaki model, and the
Raussendorf-Harrington-Goyal topological model. Here, we consider blind quantum
computation for the continuous-variable measurement-based model. We show that
blind quantum computation is possible for the infinite squeezing case. We also
show that the finite squeezing causes no additional problem in the blind setup
apart from the one inherent to the continuous-variable measurement-based
quantum computation.Comment: 20 pages, 8 figure
Unifying Quantum Computation with Projective Measurements only and One-Way Quantum Computation
Quantum measurement is universal for quantum computation. Two models for
performing measurement-based quantum computation exist: the one-way quantum
computer was introduced by Briegel and Raussendorf, and quantum computation via
projective measurements only by Nielsen. The more recent development of this
second model is based on state transfers instead of teleportation. From this
development, a finite but approximate quantum universal family of observables
is exhibited, which includes only one two-qubit observable, while others are
one-qubit observables. In this article, an infinite but exact quantum universal
family of observables is proposed, including also only one two-qubit
observable.
The rest of the paper is dedicated to compare these two models of
measurement-based quantum computation, i.e. one-way quantum computation and
quantum computation via projective measurements only. From this comparison,
which was initiated by Cirac and Verstraete, closer and more natural
connections appear between these two models. These close connections lead to a
unified view of measurement-based quantum computation.Comment: 9 pages, submitted to QI 200
Measurement-Based Quantum Turing Machines and Questions of Universalities
Quantum measurement is universal for quantum computation. This universality
allows alternative schemes to the traditional three-step organisation of
quantum computation: initial state preparation, unitary transformation,
measurement. In order to formalize these other forms of computation, while
pointing out the role and the necessity of classical control in
measurement-based computation, and for establishing a new upper bound of the
minimal resources needed to quantum universality, a formal model is introduced
by means of Measurement-based Quantum Turing Machines.Comment: 12 pages, 9 figure
- …