2,055 research outputs found
Modified TAP equations for the SK spin glass
The stability of the TAP mean field equations is reanalyzed with the
conclusion that the exclusive reason for the breakdown at the spin glass
instability is an inconsistency for the value of the local susceptibility. A
new alternative approach leads to modified equations which are in complete
agreement with the original ones above the instability. Essentially altered
results below the instability are presented and the consequences for the
dynamical mean field equations are discussed.Comment: 7 pages, 2 figures, final revised version to appear in Europhys. Let
Local Probabilistic Decoding of a Quantum Code
flip is an extremely simple and maximally local classical decoder which has
been used to great effect in certain classes of classical codes. When applied
to quantum codes there exist constant-weight errors (such as half of a
stabiliser) which are uncorrectable for this decoder, so previous studies have
considered modified versions of flip, sometimes in conjunction with other
decoders. We argue that this may not always be necessary, and present numerical
evidence for the existence of a threshold for flip when applied to the looplike
syndromes of a three-dimensional toric code on a cubic lattice. This result can
be attributed to the fact that the lowest-weight uncorrectable errors for this
decoder are closer (in terms of Hamming distance) to correctable errors than to
other uncorrectable errors, and so they are likely to become correctable in
future code cycles after transformation by additional noise. Introducing
randomness into the decoder can allow it to correct these "uncorrectable"
errors with finite probability, and for a decoding strategy that uses a
combination of belief propagation and probabilistic flip we observe a threshold
of under phenomenological noise. This is comparable to the best
known threshold for this code () which was achieved using belief
propagation and ordered statistics decoding [Higgott and Breuckmann, 2022], a
strategy with a runtime of as opposed to the ( when
parallelised) runtime of our local decoder. We expect that this strategy could
be generalised to work well in other low-density parity check codes, and hope
that these results will prompt investigation of other previously overlooked
decoders.Comment: 10 pages + 1 page appendix, 7 figures. Comments welcome.; v3
Published versio
Protein-crystal growth experiment (planned)
To evaluate the effectiveness of a microgravity environment on protein crystal growth, a system was developed using 5 cubic feet Get Away Special payload canister. In the experiment, protein (myoglobin) will be simultaneously crystallized from an aqueous solution in 16 crystallization units using three types of crystallization methods, i.e., batch, vapor diffusion, and free interface diffusion. Each unit has two compartments: one for the protein solution and the other for the ammonium sulfate solution. Compartments are separated by thick acrylic or thin stainless steel plates. Crystallization will be started by sliding out the plates, then will be periodically recorded up to 120 hours by a still camera. The temperature will be passively controlled by a phase transition thermal storage component and recorded in IC memory throughout the experiment. Microgravity environment can then be evaluated for protein crystal growth by comparing crystallization in space with that on Earth
Modified Thouless-Anderson-Palmer equations for the Sherrington-Kirkpatrick spin glass: Numerical solutions
For large but finite systems the static properties of the infinite ranged
Sherrington-Kirkpatrick model are numerically investigated in the entire the
glass regime. The approach is based on the modified Thouless-Anderson-Palmer
equations in combination with a phenomenological relaxational dynamics used as
a numerical tool. For all temperatures and all bond configurations stable and
meta stable states are found. Following a discussion of the finite size
effects, the static properties of the state of lowest free energy are presented
in the presence of a homogeneous magnetic field for all temperatures below the
spin glass temperature. Moreover some characteristic features of the meta
stable states are presented. These states exist in finite temperature intervals
and disappear via local saddle node bifurcations. Numerical evidence is found
that the excess free energy of the meta stable states remains finite in the
thermodynamic limit. This implies a the `multi-valley' structure of the free
energy on a sub-extensive scale.Comment: Revtex 10 pages 13 figures included, submitted to Phys.Rev.B.
Shortend and improved version with additional numerical dat
Hadron Physics and Confinement Physics in Lattice QCD
We are aiming to construct Quark Hadron Physics and Confinement Physics based
on QCD. Using SU(3) lattice QCD, we are investigating the three-quark
potential at T=0 and , mass spectra of positive and negative-parity
baryons in the octet and the decuplet representations of the SU(3) flavor,
glueball properties at T=0 and . We study also Confinement Physics
using lattice QCD. In the maximally abelian (MA) gauge, the off-diagonal gluon
amplitude is strongly suppressed, and then the off-diagonal gluon phase shows
strong randomness, which leads to a large effective off-diagonal gluon mass,
. Due to the large off-diagonal gluon mass in
the MA gauge, infrared QCD is abelianized like nonabelian Higgs theories. In
the MA gauge, there appears a macroscopic network of the monopole world-line
covering the whole system. From the monopole current, we extract the dual gluon
field , and examine the longitudinal magnetic screening. We obtain 0.5 GeV in the infrared region, which indicates the dual Higgs
mechanism by monopole condensation. From infrared abelian dominance and
infrared monopole condensation, low-energy QCD in the MA gauge is described
with the dual Ginzburg-Landau (DGL) theory.Comment: Invited talk given at International Symposium on Hadrons and Nuclei,
Seoul, Korea, 20-22 Feb 200
A Dynamic Service Level Negotiation Mechanism for QoS Provisioning in NGEO Satellite Networks
科研費報告書収録論文(課題番号:17500030/研究代表者:加藤寧/インターネットと高親和性を有する次世代低軌道衛星ネットワークに関する基盤研究
Weak nonlinearities: A new route to optical quantum computation
Quantum information processing (QIP) offers the promise of being able to do
things that we cannot do with conventional technology. Here we present a new
route for distributed optical QIP, based on generalized quantum non-demolition
measurements, providing a unified approach for quantum communication and
computing. Interactions between photons are generated using weak
non-linearities and intense laser fields--the use of such fields provides for
robust distribution of quantum information. Our approach requires only a
practical set of resources, and it uses these very efficiently. Thus it
promises to be extremely useful for the first quantum technologies, based on
scarce resources. Furthermore, in the longer term this approach provides both
options and scalability for efficient many-qubit QIP.Comment: 7 Pages, 4 Figure
SU(N)-symmetric quasi-probability distribution functions
We present a set of N-dimensional functions, based on generalized
SU(N)-symmetric coherent states, that represent finite-dimensional Wigner
functions, Q-functions, and P-functions. We then show the fundamental
properties of these functions and discuss their usefulness for analyzing
N-dimensional pure and mixed quantum states.Comment: 16 pages, 2 figures. Updated text to reflect referee comment
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