1,632 research outputs found
UMA (Unlicensed Mobile Access): A New Approach towards Mobility
The purpose of this document is to describe the fixed-mobile convergence solution using Unlicensed Mobile Access (UMA) technology. This document describes elements for UMA access and convergence solution and the evolution towards the IP based network. UMA technology offers an alternative to the cellular radio access network (RAN), which uses the Global System for Mobile Communications (GSM) and General Packet Radio Service/Enhanced Data rates for Global Evolution (GPRS/EDGE) core circuit, data, and IMS services through IP-based broadband connections. To deliver a seamless user experience throughout these various access networks, the UMA specifications define a new network element, the UMA Network Controller (UNC), together with associated protocols for the secure transport of GSM and GPRS/EDGE, signalling, and bearer traffic over I
Microwave Photos in High Impedance Transmission line: Dispersion, Disorder and Localization
In this thesis we will describe the theoretical and experimental studies of a TEM on-chip superconducting transmission line with a wave impedance as high as 20 , phase and group velocity of waves simultaneously reduced by a factor of 100 in a broad range of frequencies from 0 to about 10 . A conventional microwave coaxial transmission line gets its inductance and capacitance from magnetic and electric fields stored in the space between its inner and outer conductors. This in turn limits its impedance to around 50 and group velocity of waves very close to the speed of light in vacuum. In this work we are able to increase the impedance by over two orders of magnitude and reduce the group and phase velocity of waves by over two orders of magnitude as well, by constructing a coplanar transmission line out of a pair of long Al/AlOx/Al Josephson tunnel junction chains. A Josephson junction gets its inductance not from the magnetic energy but rather from the much larger kinetic energy of tunneling Cooper pairs, which is unrelated to the electromagnetic properties of vacuum. In this work we present a design of such a transmission line and low-temperature measurement of its dispersion relation. We then study and characterize the disorder present in the circuit parameters of our system and using this, we conclude that for frequencies up to 12 GHz, there is no evidence of Anderson localization of waves, even for chains exceeding 30,000 junctions. Low dissipation and absence of localization make this transmission line ideal for use in various experiments where high impedance can enable strong coupling between light and matter
Flavour Enhanced Food Recommendation
We propose a mechanism to use the features of flavour to enhance the quality
of food recommendations. An empirical method to determine the flavour of food
is incorporated into a recommendation engine based on major gustatory nerves.
Such a system has advantages of suggesting food items that the user is more
likely to enjoy based upon matching with their flavour profile through use of
the taste biological domain knowledge. This preliminary intends to spark more
robust mechanisms by which flavour of food is taken into consideration as a
major feature set into food recommendation systems. Our long term vision is to
integrate this with health factors to recommend healthy and tasty food to users
to enhance quality of life.Comment: In Proceedings of 5th International Workshop on Multimedia Assisted
Dietary Management, Nice, France, October 21, 2019, MADiMa 2019, 6 page
Rotary Endodontics in Pediatric Dentistry: Literature Review.
Pulpectomy is indicated in primary teeth with carious pulp exposures in which coronal and radicular pulp exhibits clinical signs of hyperemia or evidence of pulp necrosis with or without caries involvement. In primary teeth, it can be challenging and time-consuming, especially during canal preparation, which is considered one of the most important steps in root canal therapy. The development of NiTi rotary files has helped pediatric dentists also. With the availability of rapidly coming versions of these files, it may be difficult to pick appropriate file systems and techniques most suitable for an individual case. Practitioners must always bear in mind that all file systems have benefits and weaknesses
Down-conversion of a single photon as a probe of many-body localization
Decay of a particle into more particles is a ubiquitous phenomenon to
interacting quantum systems, taking place in colliders, nuclear reactors, or
solids. In a non-linear medium, even a single photon would decay by
down-converting (splitting) into lower frequency photons with the same total
energy, at a rate given by Fermi's Golden Rule. However, the energy
conservation condition cannot be matched precisely if the medium is finite and
only supports quantized modes. In this case, the photon's fate becomes the
long-standing question of many-body localization (MBL), originally formulated
as a gedanken experiment for the lifetime of a single Fermi-liquid
quasiparticle confined to a quantum dot. Here we implement such an experiment
using a superconducting multi-mode cavity, the non-linearity of which was
tailored to strongly violate the photon number conservation. The resulting
interaction attempts to convert a single photon excitation into a shower of
low-energy photons, but fails due to the MBL mechanism, which manifests as a
striking spectral fine structure of multi-particle resonances at the cavity's
standing wave mode frequencies. Each resonance was identified as a many-body
state of radiation composed of photons from a broad frequency range, and not
obeying the Fermi's Golden Rule theory. Our result introduces a new platform to
explore fundamentals of MBL without having to control many atoms or qubits
Inelastic scattering of a photon by a quantum phase-slip
Spontaneous decay of a single photon is a notoriously inefficient process in
nature irrespective of the frequency range. We report that a quantum phase-slip
fluctuation in high-impedance superconducting waveguides can split a single
incident microwave photon into a large number of lower-energy photons with a
near unit probability. The underlying inelastic photon-photon interaction has
no analogs in non-linear optics. Instead, the measured decay rates are
explained without adjustable parameters in the framework of a new model of a
quantum impurity in a Luttinger liquid. Our result connects circuit quantum
electrodynamics to critical phenomena in two-dimensional boundary quantum field
theories, important in the physics of strongly-correlated systems. The photon
lifetime data represents a rare example of verified and useful quantum
many-body simulation.Comment: minor revision for clarity, supplementary material is available at
www.superconducting-circuits.co
Demonstrating a superconducting dual-rail cavity qubit with erasure-detected logical measurements
A critical challenge in developing scalable error-corrected quantum systems
is the accumulation of errors while performing operations and measurements. One
promising approach is to design a system where errors can be detected and
converted into erasures. A recent proposal aims to do this using a dual-rail
encoding with superconducting cavities. In this work, we implement such a
dual-rail cavity qubit and use it to demonstrate a projective logical
measurement with erasure detection. We measure logical state preparation and
measurement errors at the -level and detect over of cavity decay
events as erasures. We use the precision of this new measurement protocol to
distinguish different types of errors in this system, finding that while decay
errors occur with probability per microsecond, phase errors occur
6 times less frequently and bit flips occur at least 170 times less frequently.
These findings represent the first confirmation of the expected error hierarchy
necessary to concatenate dual-rail erasure qubits into a highly efficient
erasure code
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