128,538 research outputs found
Dynamic Provable Data Possession Protocols with Public Verifiability and Data Privacy
Cloud storage services have become accessible and used by everyone.
Nevertheless, stored data are dependable on the behavior of the cloud servers,
and losses and damages often occur. One solution is to regularly audit the
cloud servers in order to check the integrity of the stored data. The Dynamic
Provable Data Possession scheme with Public Verifiability and Data Privacy
presented in ACISP'15 is a straightforward design of such solution. However,
this scheme is threatened by several attacks. In this paper, we carefully
recall the definition of this scheme as well as explain how its security is
dramatically menaced. Moreover, we proposed two new constructions for Dynamic
Provable Data Possession scheme with Public Verifiability and Data Privacy
based on the scheme presented in ACISP'15, one using Index Hash Tables and one
based on Merkle Hash Trees. We show that the two schemes are secure and
privacy-preserving in the random oracle model.Comment: ISPEC 201
Orbital-resolved vortex core states in FeSe Superconductors: calculation based on a three-orbital model
We study electronic structure of vortex core states of FeSe superconductors
based on a t three-orbital model by solving the Bogoliubov-de
Gennes(BdG) equation self-consistently. The orbital-resolved vortex core states
of different pairing symmetries manifest themselves as distinguishable
structures due to different quasi-particle wavefunctions. The obtained vortices
are classified in terms of the invariant subgroups of the symmetry group of the
mean-field Hamiltonian in the presence of magnetic field. Isotropic and
anisotropic wave vortices have symmetry for each orbital, whereas
wave vortices show symmetry for orbitals
and symmetry for orbital. In the case of
wave vortices, hybridized-pairing between and orbitals gives
rise to a relative phase difference in terms of gauge transformed pairing order
parameters between and orbitals, which is essentially
caused by a transformation of co-representation of and
subgroup. The calculated local density of states(LDOS) of wave
vortices show qualitatively similar pattern with experiment results. The phase
difference of between and orbital-resolved
wave vortices can be verified by further experiment observation
Determination of anisotropic dipole moments in self-assembled quantum dots using Rabi oscillations
By investigating the polarization-dependent Rabi oscillations using
photoluminescence spectroscopy, we determined the respective transition dipole
moments of the two excited excitonic states |Ex> and |Ey> of a single
self-assembled quantum dot that are nondegenerate due to shape anisotropy. We
find that the ratio of the two dipole moments is close to the physical
elongation ratio of the quantum dot.Comment: 11 pages, 2 figures, MS Word generated PDF fil
Maximum Path Information and Fokker-Planck Equation
We present in this paper a rigorous method to derive the nonlinear
Fokker-Planck (FP) equation of anomalous diffusion directly from a
generalization of the principle of least action of Maupertuis proposed by Wang
for smooth or quasi-smooth irregular dynamics evolving in Markovian process.
The FP equation obtained may take two different but equivalent forms. It was
also found that the diffusion constant may depend on both q (the index of
Tsallis entropy) and the time t.Comment: 7 page
Hydrogen as a Source of Flux Noise in SQUIDs
Superconducting qubits are hampered by flux noise produced by surface spins
from a variety of microscopic sources. Recent experiments indicated that
hydrogen (H) atoms may be one of those sources. Using density functional theory
calculations, we report that H atoms either embedded in, or adsorbed on, an
a-Al2O3(0001) surface have sizeable spin moments ranging from 0.81 to 0.87 uB
with energy barriers for spin reorientation as low as ~10 mK. Furthermore, H
adatoms on the surface attract gas molecules such as O2, producing new spin
sources. We propose coating the surface with graphene to eliminate H-induced
surface spins and to protect the surface from other adsorbates.Comment: 12 pages, 4 figure
Design of a 2.4 GHz High-Performance Up-Conversion Mixer with Current Mirror Topology
In this paper, a low voltage low power up-conversion mixer, designed in a Chartered 0.18 μm RFCMOS technology, is proposed to realize the transmitter front-end in the frequency band of 2.4 GHz. The up-conversion mixer uses the current mirror topology and current-bleeding technique in both the driver and switching stages with a simple degeneration resistor. The proposed mixer converts an input of 100 MHz intermediate frequency (IF) signal to an output of 2.4 GHz radio frequency (RF) signal, with a local oscillator (LO) power of 2 dBm at 2.3 GHz. A comparison with conventional CMOS up-conversion mixer shows that this mixer has advantages of low voltage, low power consumption and high-performance. The post-layout simulation results demonstrate that at 2.4 GHz, the circuit has a conversion gain of 7.1 dB, an input-referred third-order intercept point (IIP3) of 7.3 dBm and a noise figure of 11.9 dB, while drawing only 3.8 mA for the mixer core under a supply voltage of 1.2 V. The chip area including testing pads is only 0.62×0.65 mm2
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