2,405 research outputs found
Relational time for systems of oscillators
Using an elementary example based on two simple harmonic oscillators, we show
how a relational time may be defined that leads to an approximate Schrodinger
dynamics for subsystems, with corrections leading to an intrinsic decoherence
in the energy eigenstates of the subsystem.Comment: Contribution to the Int. J. of Quant. Info. issue dedicated to the
memory of Asher Pere
Hybridization of Magnetism and Piezoelectricity for an Energy Scavenger based on Temporal Variation of Temperature
Autonomous microsystems are confronted today to a major challenge : the one
of energy supply. Energy scavenging, i.e. collecting energy from the ambient
environment has been developed to answer this problematic. Various sources have
already been successfully used (solar, vibration). This article presents
temporal variations of temperature as a new source of exploitable energy. A
brief review will take place at the beginning, exposing the different
approaches used in the past. Then we will focus our attention on hybridization
of magnetism and piezoelectricity. A new kind of thermal generator is proposed
and a preliminary model is exposed. Conclusions will be drawn on the
suitability of this prototype and the improvements that are needed to increase
its potential.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
Alien Registration- Poulin, Henry G. (Lewiston, Androscoggin County)
https://digitalmaine.com/alien_docs/27956/thumbnail.jp
Alien Registration- Poulin, Alphonse G. (Millinocket, Penobscot County)
https://digitalmaine.com/alien_docs/7377/thumbnail.jp
Alien Registration- Poulin, Lorenzo G. (Winslow, Kennebec County)
https://digitalmaine.com/alien_docs/17023/thumbnail.jp
Quantum Metropolis Sampling
The original motivation to build a quantum computer came from Feynman who
envisaged a machine capable of simulating generic quantum mechanical systems, a
task that is believed to be intractable for classical computers. Such a machine
would have a wide range of applications in the simulation of many-body quantum
physics, including condensed matter physics, chemistry, and high energy
physics. Part of Feynman's challenge was met by Lloyd who showed how to
approximately decompose the time-evolution operator of interacting quantum
particles into a short sequence of elementary gates, suitable for operation on
a quantum computer. However, this left open the problem of how to simulate the
equilibrium and static properties of quantum systems. This requires the
preparation of ground and Gibbs states on a quantum computer. For classical
systems, this problem is solved by the ubiquitous Metropolis algorithm, a
method that basically acquired a monopoly for the simulation of interacting
particles. Here, we demonstrate how to implement a quantum version of the
Metropolis algorithm on a quantum computer. This algorithm permits to sample
directly from the eigenstates of the Hamiltonian and thus evades the sign
problem present in classical simulations. A small scale implementation of this
algorithm can already be achieved with today's technologyComment: revised versio
Alien Registration- Poulin, Marie Therese G. (Waterville, Kennebec County)
https://digitalmaine.com/alien_docs/14772/thumbnail.jp
Thermalization, Error-Correction, and Memory Lifetime for Ising Anyon Systems
We consider two-dimensional lattice models that support Ising anyonic
excitations and are coupled to a thermal bath. We propose a phenomenological
model for the resulting short-time dynamics that includes pair-creation,
hopping, braiding, and fusion of anyons. By explicitly constructing topological
quantum error-correcting codes for this class of system, we use our
thermalization model to estimate the lifetime of the quantum information stored
in the encoded spaces. To decode and correct errors in these codes, we adapt
several existing topological decoders to the non-Abelian setting. We perform
large-scale numerical simulations of these two-dimensional Ising anyon systems
and find that the thresholds of these models range between 13% to 25%. To our
knowledge, these are the first numerical threshold estimates for quantum codes
without explicit additive structure.Comment: 34 pages, 9 figures; v2 matches the journal version and corrects a
misstatement about the detailed balance condition of our Metropolis
simulations. All conclusions from v1 are unaffected by this correctio
Practical learning method for multi-scale entangled states
We describe a method for reconstructing multi-scale entangled states from a
small number of efficiently-implementable measurements and fast
post-processing. The method only requires single particle measurements and the
total number of measurements is polynomial in the number of particles. Data
post-processing for state reconstruction uses standard tools, namely matrix
diagonalisation and conjugate gradient method, and scales polynomially with the
number of particles. Our method prevents the build-up of errors from both
numerical and experimental imperfections
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