Fault-tolerant, high-level quantum circuits: form, compilation and description

Fault-tolerant quantum error correction is a necessity for any quantum architecture destined to tackle interesting, large-scale problems. Its theoretical formalism has been well founded for nearly two decades. However, we still do not have an appropriate compiler to produce a fault-tolerant, error-corrected description from a higher-level quantum circuit for state-of the-art hardware models. There are many technical hurdles, including dynamic circuit constructions that occur when constructing fault-tolerant circuits with commonly used error correcting codes. We introduce a package that converts high-level quantum circuits consisting of commonly used gates into a form employing all decompositions and ancillary protocols needed for fault-tolerant error correction. We call this form the (I)initialisation, (C)NOT, (M)measurement form (ICM) and consists of an initialisation layer of qubits into one of four distinct states, a massive, deterministic array of CNOT operations and a seri… …

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Quantum networks: where should we be heading?

Quantum key distribution network has become a reality in practical environment. Quantum repeaters have been explored in various physical systems and their combinations. For practical use of them, these new paradigms must be combined with existing or emerging infrastructures of communication and security systems. In this article, we discussed how quantum network can be combined with modern cryptographic technologies in fibre network and with emerging mobile terminals in wireless network, creating new solutions for the future cryptographic and communication systems. Our discussions are summarised in a roadmap. …

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A New Path to Equal-Angle Lines

Equiangular lines are an elemental part of geometry. Mathematicians have discovered a tighter limit on the number of such lines that exist in every dimension. …

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Physicists discover hidden aspects of electrodynamics

Radio waves, microwaves and even light itself are all made of electric and magnetic fields. The classical theory of electromagnetism was completed in the 1860s by James Clerk Maxwell. At the time, Maxwell’s theory was revolutionary, and provided a unified framework to understand electricity, magnetism and optics. Now, new research advances knowledge of this theory.

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‘Indistinguishable photons’ key to advancing quantum technologies

To really take off, advanced quantum information processing will require getting a better (experimental) grasp of an essential phenomenon called “indistinguishable photons.” A high degree of “indistinguishability” requires almost complete wave-packet overlap, or perfect photon matching, of energy, space, time and polarization.

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Proton-nuclei smashups yield clues about ‘quark gluon plasma’

Findings from physicists working at Europe’s Large Hadron Collider are providing new insight about an exotic state of matter called the ‘quark-gluon plasma’ that occurs when protons and neutrons melt.

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Is It Friday the 13th Again?

How our society defines years, months and weeks can seem frustratingly arbitrary. Can you bring order to our unruly calendar? …

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New measurements suggest ‘antineutrino anomaly’ fueled by modeling error

Results from a new study could explain a mismatch between predictions and recent measurements of ghostly particles streaming from nuclear reactors — the so-called “reactor antineutrino anomaly” that has puzzled physicists since 2011.

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