14,435 research outputs found
Towards musical interaction : 'Schismatics' for e-violin and computer.
This paper discusses the evolution of the Max/MSP
patch used in schismatics (2007, rev. 2010) for electric
violin (Violectra) and computer, by composer Sam
Hayden in collaboration with violinist Mieko Kanno.
schismatics involves a standard performance paradigm
of a fixed notated part for the e-violin with sonically unfixed
live computer processing. Hayden was unsatisfied
with the early version of the piece: the use of attack
detection on the live e-violin playing to trigger stochastic
processes led to an essentially reactive behaviour in the
computer, resulting in a somewhat predictable one-toone
sonic relationship between them. It demonstrated
little internal relationship between the two beyond an
initial e-violin ‘action’ causing a computer ‘event’. The
revisions in 2010, enabled by an AHRC Practice-Led
research award, aimed to achieve 1) a more interactive
performance situation and 2) a subtler and more
‘musical’ relationship between live and processed
sounds. This was realised through the introduction of
sound analysis objects, in particular machine listening
and learning techniques developed by Nick Collins. One
aspect of the programming was the mapping of analysis
data to synthesis parameters, enabling the computer
transformations of the e-violin to be directly related to
Kanno’s interpretation of the piece in performance
Spectral Analysis Program (SAP)
Program eliminates or reduces time-consuming aspects of computation of power spectrum for high-frequency communication system. This program was written in FORTRAN IV for UNIVAC 1230 or 1108 computer
Two-message quantum interactive proofs and the quantum separability problem
Suppose that a polynomial-time mixed-state quantum circuit, described as a
sequence of local unitary interactions followed by a partial trace, generates a
quantum state shared between two parties. One might then wonder, does this
quantum circuit produce a state that is separable or entangled? Here, we give
evidence that it is computationally hard to decide the answer to this question,
even if one has access to the power of quantum computation. We begin by
exhibiting a two-message quantum interactive proof system that can decide the
answer to a promise version of the question. We then prove that the promise
problem is hard for the class of promise problems with "quantum statistical
zero knowledge" (QSZK) proof systems by demonstrating a polynomial-time Karp
reduction from the QSZK-complete promise problem "quantum state
distinguishability" to our quantum separability problem. By exploiting Knill's
efficient encoding of a matrix description of a state into a description of a
circuit to generate the state, we can show that our promise problem is NP-hard
with respect to Cook reductions. Thus, the quantum separability problem (as
phrased above) constitutes the first nontrivial promise problem decidable by a
two-message quantum interactive proof system while being hard for both NP and
QSZK. We also consider a variant of the problem, in which a given
polynomial-time mixed-state quantum circuit accepts a quantum state as input,
and the question is to decide if there is an input to this circuit which makes
its output separable across some bipartite cut. We prove that this problem is a
complete promise problem for the class QIP of problems decidable by quantum
interactive proof systems. Finally, we show that a two-message quantum
interactive proof system can also decide a multipartite generalization of the
quantum separability problem.Comment: 34 pages, 6 figures; v2: technical improvements and new result for
the multipartite quantum separability problem; v3: minor changes to address
referee comments, accepted for presentation at the 2013 IEEE Conference on
Computational Complexity; v4: changed problem names; v5: updated references
and added a paragraph to the conclusion to connect with prior work on
separability testin
A Signal Distribution Network for Sequential Quantum-dot Cellular Automata Systems
The authors describe a signal distribution network for sequential systems constructed using the Quantum-dot Cellular Automata (QCA) computing paradigm. This network promises to enable the construction of arbitrarily complex QCA sequential systems in which all wire crossings are performed using nearest neighbor interactions, which will improve the thermal behavior of QCA systems as well as their resistance to stray charge and fabrication imperfections. The new sequential signal distribution network is demonstrated by the complete design and simulation of a two-bit counter, a three-bit counter, and a pattern detection circuit
Quantum trade-off coding for bosonic communication
The trade-off capacity region of a quantum channel characterizes the optimal
net rates at which a sender can communicate classical, quantum, and entangled
bits to a receiver by exploiting many independent uses of the channel, along
with the help of the same resources. Similarly, one can consider a trade-off
capacity region when the noiseless resources are public, private, and secret
key bits. In [Phys. Rev. Lett. 108, 140501 (2012)], we identified these
trade-off rate regions for the pure-loss bosonic channel and proved that they
are optimal provided that a longstanding minimum output entropy conjecture is
true. Additionally, we showed that the performance gains of a trade-off coding
strategy when compared to a time-sharing strategy can be quite significant. In
the present paper, we provide detailed derivations of the results announced
there, and we extend the application of these ideas to thermalizing and
amplifying bosonic channels. We also derive a "rule of thumb" for trade-off
coding, which determines how to allocate photons in a coding strategy if a
large mean photon number is available at the channel input. Our results on the
amplifying bosonic channel also apply to the "Unruh channel" considered in the
context of relativistic quantum information theory.Comment: 20 pages, 7 figures, v2 has a new figure and a proof that the regions
are optimal for the lossy bosonic channel if the entropy photon-number
inequality is true; v3, submission to Physical Review A (see related work at
http://link.aps.org/doi/10.1103/PhysRevLett.108.140501); v4, final version
accepted into Physical Review
Leggett-Garg inequalities and the geometry of the cut polytope
The Bell and Leggett-Garg tests offer operational ways to demonstrate that
non-classical behavior manifests itself in quantum systems, and
experimentalists have implemented these protocols to show that classical
worldviews such as local realism and macrorealism are false, respectively.
Previous theoretical research has exposed important connections between more
general Bell inequalities and polyhedral combinatorics. We show here that
general Leggett-Garg inequalities are closely related to the cut polytope of
the complete graph, a geometric object well-studied in combinatorics. Building
on that connection, we offer a family of Leggett-Garg inequalities that are not
trivial combinations of the most basic Leggett-Garg inequalities. We then show
that violations of macrorealism can occur in surprising ways, by giving an
example of a quantum system that violates the new "pentagon" Leggett-Garg
inequality but does not violate any of the basic "triangle" Leggett-Garg
inequalities.Comment: 5 pages, 1 figur
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