186 research outputs found
Arithmetic on a Distributed-Memory Quantum Multicomputer
We evaluate the performance of quantum arithmetic algorithms run on a
distributed quantum computer (a quantum multicomputer). We vary the node
capacity and I/O capabilities, and the network topology. The tradeoff of
choosing between gates executed remotely, through ``teleported gates'' on
entangled pairs of qubits (telegate), versus exchanging the relevant qubits via
quantum teleportation, then executing the algorithm using local gates
(teledata), is examined. We show that the teledata approach performs better,
and that carry-ripple adders perform well when the teleportation block is
decomposed so that the key quantum operations can be parallelized. A node size
of only a few logical qubits performs adequately provided that the nodes have
two transceiver qubits. A linear network topology performs acceptably for a
broad range of system sizes and performance parameters. We therefore recommend
pursuing small, high-I/O bandwidth nodes and a simple network. Such a machine
will run Shor's algorithm for factoring large numbers efficiently.Comment: 24 pages, 10 figures, ACM transactions format. Extended version of
Int. Symp. on Comp. Architecture (ISCA) paper; v2, correct one circuit error,
numerous small changes for clarity, add reference
Distributed Quantum Computation Architecture Using Semiconductor Nanophotonics
In a large-scale quantum computer, the cost of communications will dominate
the performance and resource requirements, place many severe demands on the
technology, and constrain the architecture. Unfortunately, fault-tolerant
computers based entirely on photons with probabilistic gates, though equipped
with "built-in" communication, have very large resource overheads; likewise,
computers with reliable probabilistic gates between photons or quantum memories
may lack sufficient communication resources in the presence of realistic
optical losses. Here, we consider a compromise architecture, in which
semiconductor spin qubits are coupled by bright laser pulses through
nanophotonic waveguides and cavities using a combination of frequent
probabilistic and sparse determinstic entanglement mechanisms. The large
photonic resource requirements incurred by the use of probabilistic gates for
quantum communication are mitigated in part by the potential high-speed
operation of the semiconductor nanophotonic hardware. The system employs
topological cluster-state quantum error correction for achieving
fault-tolerance. Our results suggest that such an architecture/technology
combination has the potential to scale to a system capable of attacking
classically intractable computational problems.Comment: 29 pages, 7 figures; v2: heavily revised figures improve architecture
presentation, additional detail on physical parameters, a few new reference
Advanced software techniques for space shuttle data management systems Final report
Airborne/spaceborn computer design and techniques for space shuttle data management system
Parallel Computers and Complex Systems
We present an overview of the state of the art and future trends in high performance parallel and distributed computing, and discuss techniques for using such computers in the simulation of complex problems in computational science. The use of high performance parallel computers can help improve our understanding of complex systems, and the converse is also true --- we can apply techniques used for the study of complex systems to improve our understanding of parallel computing. We consider parallel computing as the mapping of one complex system --- typically a model of the world --- into another complex system --- the parallel computer. We study static, dynamic, spatial and temporal properties of both the complex systems and the map between them. The result is a better understanding of which computer architectures are good for which problems, and of software structure, automatic partitioning of data, and the performance of parallel machines
Layered architecture for quantum computing
We develop a layered quantum computer architecture, which is a systematic
framework for tackling the individual challenges of developing a quantum
computer while constructing a cohesive device design. We discuss many of the
prominent techniques for implementing circuit-model quantum computing and
introduce several new methods, with an emphasis on employing surface code
quantum error correction. In doing so, we propose a new quantum computer
architecture based on optical control of quantum dots. The timescales of
physical hardware operations and logical, error-corrected quantum gates differ
by several orders of magnitude. By dividing functionality into layers, we can
design and analyze subsystems independently, demonstrating the value of our
layered architectural approach. Using this concrete hardware platform, we
provide resource analysis for executing fault-tolerant quantum algorithms for
integer factoring and quantum simulation, finding that the quantum dot
architecture we study could solve such problems on the timescale of days.Comment: 27 pages, 20 figure
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