332 research outputs found
A spintronic source of circularly polarized single photons
We present a spintronic single photon source which emits circularly polarized
light, where the helicity is determined by an applied magnetic field. Photons
are emitted from an InGaAs quantum dot inside an electrically operated spin
light-emitting diode, which comprises the diluted magnetic semiconductor
ZnMnSe. The circular polarization degree of the emitted light is high, reaching
83% at an applied magnetic field of 2T and 96% at 6 T. Autocorrelation traces
recorded in pulsed operation mode prove the emitted light to be antibunched.
The two circular polarization states could be used for representing quantum
states |0> and |1> in quantum cryptography implementations
Analysing Survey Propagation Guided Decimationon Random Formulas
Let be a uniformly distributed random -SAT formula with
variables and clauses. For clauses/variables ratio the formula is satisfiable with high
probability. However, no efficient algorithm is known to provably find a
satisfying assignment beyond with a non-vanishing
probability. Non-rigorous statistical mechanics work on -CNF led to the
development of a new efficient "message passing algorithm" called \emph{Survey
Propagation Guided Decimation} [M\'ezard et al., Science 2002]. Experiments
conducted for suggest that the algorithm finds satisfying assignments
close to . However, in the present paper we prove that the
basic version of Survey Propagation Guided Decimation fails to solve random
-SAT formulas efficiently already for
with almost a factor below
.Comment: arXiv admin note: substantial text overlap with arXiv:1007.1328 by
other author
Point Cloud Network: An Order of Magnitude Improvement in Linear Layer Parameter Count
This paper introduces the Point Cloud Network (PCN) architecture, a novel
implementation of linear layers in deep learning networks, and provides
empirical evidence to advocate for its preference over the Multilayer
Perceptron (MLP) in linear layers. We train several models, including the
original AlexNet, using both MLP and PCN architectures for direct comparison of
linear layers (Krizhevsky et al., 2012). The key results collected are model
parameter count and top-1 test accuracy over the CIFAR-10 and CIFAR-100
datasets (Krizhevsky, 2009). AlexNet-PCN16, our PCN equivalent to AlexNet,
achieves comparable efficacy (test accuracy) to the original architecture with
a 99.5% reduction of parameters in its linear layers. All training is done on
cloud RTX 4090 GPUs, leveraging pytorch for model construction and training.
Code is provided for anyone to reproduce the trials from this paper
Non-interacting central site model: localization and logarithmic entanglement growth
We investigate the stationary and dynamical behavior of an Anderson localized
chain coupled to a single central bound state. The coupling to the central site
partially dilutes the Anderson localized peak towards the nearly resonant
sites. In particular, the number of resonantly coupled sites remains finite in
the thermodynamic limit. This is further supported by a multifractal analysis
of eigenstates that shows the frozen spectrum of fractal dimension, which is
characteristic for localized phases in models with power-law hopping. Although
the well-known Fano-resonance problem is seemingly similar to our system, it
fails to describe it because of the absence of level repulsion within the
energy spectrum. For weak coupling strengths to the central site, we identify a
regime with a logarithmic in time transport of particles and information.Comment: 10 pages, 7 figure
Czech Public Procurement: the Fight Against Corruption
Since the Czech Republic’s transition from communism, the area of Czech public procurement has been vulnerable to corruption. Several organizations are fighting to reduce corruption in Czech public procurement, but there are still numerous ways they can improve the success of their fight
- …