535 research outputs found
Scalable designs for quantum computing with rare-earth-ion-doped crystals
Due to inhomogeneous broadening, the absorption lines of rare-earth-ion
dopands in crystals are many order of magnitudes wider than the homogeneous
linewidths. Several ways have been proposed to use ions with different
inhomogeneous shifts as qubit registers, and to perform gate operations between
such registers by means of the static dipole coupling between the ions.
In this paper we show that in order to implement high-fidelity quantum gate
operations by means of the static dipole interaction, we require the
participating ions to be strongly coupled, and that the density of such
strongly coupled registers in general scales poorly with register size.
Although this is critical to previous proposals which rely on a high density of
functional registers, we describe architectures and preparation strategies that
will allow scalable quantum computers based on rare-earth-ion doped crystals.Comment: Submitted to Phys. Rev.
Regeneration of photon echoes with amplified photon echoes
Photon-echo-based devices have been proposed for many applications in data storage, image processing, and optical communications. Many of these applications would benefit if the output from the photon-echo process could be used as input in a second photon-echo process. We demonstrate the generation of such secondary echoes, using the amplified output from an initial photon-echo process. The amplification is performed with a Pr:ZBLAN fiber amplifier, which gives a gain of more than 300 at 606 nm when pumped with 320 mW of power at 476 nm
Coherent control of collective spontaneous emission in an extended atomic ensemble and quantum storage
Coherent control of collective spontaneous emission in an extended atomic
ensemble resonantly interacting with single-photon wave packets is analyzed. A
scheme for coherent manipulation of collective atomic states is developed such
that superradiant states of the atomic system can be converted into subradiant
ones and vice versa. Possible applications of such a scheme for optical quantum
state storage and single-photon wave packet shaping are discussed. It is shown
that also in the absence of inhomogeneous broadening of the resonant line,
single-photon wave packets with arbitrary pulse shape may be recorded as a
subradiant state and reconstructed even although the duration of the wave
packets is larger than the superradiant life-time. Specifically the
applicability for storing time-bin qubits, which are used in quantum
cryptography is analyzed.Comment: 11 pages, 4 figures, submitted to PR
Quantum memory for non-stationary light fields based on controlled reversible inhomogeneous broadening
We propose a new method for efficient storage and recall of non-stationary
light fields, e.g. single photon time-bin qubits, in optically dense atomic
ensembles. Our approach to quantum memory is based on controlled, reversible,
inhomogeneous broadening. We briefly discuss experimental realizations of our
proposal.Comment: 4 page
Nanosecond image processing using stimulated photon echoes
Processing of two-dimensional images on a nanosecond time scale is demonstrated using the stimulated photon echoes in a rare-earth-doped crystal (0.1 at. \% Pr3:LaF3). Two spatially encoded laser pulses (pictures) resonant with the 3P0-3H4 transition of Pr3 were stored by focusing the image pulses sequentially into the Pr3:LaF3 crystal. The stored information is retrieved and processed by a third read pulse, generating the echo that is the spatial convolution or correlation of the input images. Application of this scheme to high-speed pattern recognition is discussed
First Application of Pulse-Shape Analysis to Silicon Micro-Strip Detectors
The method of pulse-shape analysis (PSA) for particle identification (PID)
was applied to a double-sided silicon strip detector (DSSD) with a strip pitch
of 300 \{mu}m. We present the results of test measurements with particles from
the reactions of a 70 MeV 12C beam impinging on a mylar target. Good separation
between protons and alpha particles down to 3 MeV has been obtained when
excluding the interstrip events of the DSSD from the analysis.Comment: 7 pages, 6 figures, submitted to Nuclear Inst. and Methods in Physics
Research
Does Greater Low Frequency EEG Activity in Normal Immaturity and in Children with Epilepsy Arise in the Same Neuronal Network?
Greater low frequency power (<8Hz) in the electroencephalogram (EEG) at rest is normal in the immature developing brain of children when compared to adults. Children with epilepsy also have greater low frequency interictal resting EEG activity. Whether these power elevations reflect brain immaturity due to a developmental lag or the underlying epileptic pathophysiology is unclear. The present study addresses this question by analyzing spectral EEG topographies and sources for normally developing children and children with epilepsy. We first compared the resting EEG of healthy children to that of healthy adults to isolate effects related to normal brain immaturity. Next, we compared the EEG from 10 children with generalized cryptogenic epilepsy to the EEG of 24 healthy children to isolate effects related to epilepsy. Spectral analysis revealed that global low (delta: 1-3Hz, theta: 4-7Hz), medium (alpha: 8-12Hz) and high (beta: 13-25Hz) frequency EEG activity was greater in children without epilepsy compared to adults, and even further elevated for children with epilepsy. Topographical and tomographic EEG analyses showed that normal immaturity corresponded to greater delta and theta activity at fronto-central scalp and brain regions, respectively. In contrast, the epilepsy-related activity elevations were predominantly in the alpha band at parieto-occipital electrodes and brain regions, respectively. We conclude that lower frequency activity can be a sign of normal brain immaturity or brain pathology depending on the specific topography and frequency of the oscillating neuronal networ
Exploiting Deep Neural Networks for Intention Mining
© 2020 ACM. In the current era of digital media, people are greatly interested to express themselves on online interaction which produces a huge amount of data. The user generated content may contain user\u27s emotions, opinions, daily events and specially their intent or motive behind their communication. Intention identification/mining of user\u27s reviews, that is whether a user review contains intent or not, from social media network, is an emerging area and is in great demand in various fields like online advertising, improving customer services and decision making. Until now, a lot of work has been performed by researchers on user intention identification using machine learning approaches. However, it is demanded to focus on deep neural network methods. In this research work, we have conducted experimentation on intention dataset using a deep learning method namely CNN+BILSTM. The results exhibit that the proposed model efficiently performed identification of intention sentences in user generated text with a 90% accuracy
Study of bound states in 12Be through low-energy 11Be(d,p)-transfer reactions
The bound states of 12Be have been studied through a 11Be(d,p)12Be transfer
reaction experiment in inverse kinematics. A 2.8 MeV/u beam of 11Be was
produced using the REX-ISOLDE facility at CERN. The outgoing protons were
detected with the T-REX silicon detector array. The MINIBALL germanium array
was used to detect gamma rays from the excited states in 12Be. The gamma-ray
detection enabled a clear identification of the four known bound states in
12Be, and each of the states has been studied individually. Differential cross
sections over a large angular range have been extracted. Spectroscopic factors
for each of the states have been determined from DWBA calculations and have
been compared to previous experimental and theoretical results
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