12,439 research outputs found
One-way quantum computing with arbitrarily large time-frequency continuous-variable cluster states from a single optical parametric oscillator
One-way quantum computing is experimentally appealing because it requires
only local measurements on an entangled resource called a cluster state.
Record-size, but non-universal, continuous-variable cluster states were
recently demonstrated separately in the time and frequency domains. We propose
to combine these approaches into a scalable architecture in which a single
optical parametric oscillator and simple interferometer entangle up to
( frequencies) (unlimited number of temporal modes) into
a new and computationally universal continuous-variable cluster state. We
introduce a generalized measurement protocol to enable improved computational
performance on this new entanglement resource.Comment: (v4) Consistent with published version; (v3) Fixed typo in arXiv
abstract, 14 pages, 8 figures; (v2) Supplemental material incorporated into
main text, additional explanations added, results unchanged, 14 pages, 8
figures; (v1) 5 pages (3 figures) + 6 pages (5 figures) of supplemental
material; submitted for publicatio
Characterizing finite-dimensional quantum behavior
We study and extend the semidefinite programming (SDP) hierarchies introduced
in [Phys. Rev. Lett. 115, 020501] for the characterization of the statistical
correlations arising from finite dimensional quantum systems. First, we
introduce the dimension-constrained noncommutative polynomial optimization
(NPO) paradigm, where a number of polynomial inequalities are defined and
optimization is conducted over all feasible operator representations of bounded
dimensionality. Important problems in device independent and semi-device
independent quantum information science can be formulated (or almost
formulated) in this framework. We present effective SDP hierarchies to attack
the general dimension-constrained NPO problem (and related ones) and prove
their asymptotic convergence. To illustrate the power of these relaxations, we
use them to derive new dimension witnesses for temporal and Bell-type
correlation scenarios, and also to bound the probability of success of quantum
random access codes.Comment: 17 page
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