11,715 research outputs found
Terahertz quantum plasmonics at nanoscales and angstrom scales
Through the manipulation of metallic structures, light-matter interaction can enter into the realm of quantum mechanics. For example, intense terahertz pulses illuminating a metallic nanotip can promote terahertz field-driven electron tunneling to generate enormous electron emission currents in a subpicosecond time scale. By decreasing the dimension of the metallic structures down to the nanoscale and angstrom scale, one can obtain a strong field enhancement of the incoming terahertz field to achieve atomic field strength of the order of V/nm, driving electrons in the metal into tunneling regime by overcoming the potential barrier. Therefore, designing and optimizing the metal structure for high field enhancement are an essential step for studying the quantum phenomena with terahertz light. In this review, we present several types of metallic structures that can enhance the coupling of incoming terahertz pulses with the metals, leading to a strong modification of the potential barriers by the terahertz electric fields. Extreme nonlinear responses are expected, providing opportunities for the terahertz light for the strong light-matter interaction. Starting from a brief review about the terahertz field enhancement on the metallic structures, a few examples including metallic tips, dipole antenna, and metal nanogaps are introduced for boosting the quantum phenomena. The emerging techniques to control the electron tunneling driven by the terahertz pulse have a direct impact on the ultrafast science and on the realization of next-generation quantum devices
Test of semi-local duality in a large framework
In this paper we test the semi-local duality based on the method of Ref.[1]
for calculating final-state interactions at varying number of colors ().
We compute the amplitudes by dispersion relations that respect analyticity and
coupled channel unitarity, as well as accurately describing experiment. The
dependence of the scattering amplitudes is obtained by
comparing these amplitudes to the one of chiral perturbation theory. The
semi-local duality is investigated by varying . Our results show that the
semi-local duality is not violated when is large. At large , the
contributions of the , the and the cancel
that of the in the finite energy sum rules, while the
has almost no effect. This gives further credit to the method developed in
Ref.[1] for investigating the dependence of hadron-hadron scattering with
final-state interactions. This study is also helpful to understand the
structure of the scalar mesons.Comment: 8 pages, 5 figures, several comments are adde
Pole analysis on the hadron spectroscopy of
In this paper we study the spectroscopy in the process of
. The final state interactions of coupled channel
~-~ ~-~ are constructed
based on K-matrix with the Chew-Mandelstam function. We build the amplitude according to the Au-Morgan-Pennington method. The event
shape is fitted and the decay width of is used to
constrain the parameters, too. With the amplitudes we extract out the poles and
their residues. Our amplitude and pole analysis suggest that the
should be molecule, the could be an S-wave
compact pentaquark state, and the structure around is caused by the
cusp effect. The future experimental measurement of the decays of and would further
help to study the nature of these resonances.Comment: updated to the published versio
Human and Machine Speaker Recognition Based on Short Trivial Events
Trivial events are ubiquitous in human to human conversations, e.g., cough,
laugh and sniff. Compared to regular speech, these trivial events are usually
short and unclear, thus generally regarded as not speaker discriminative and so
are largely ignored by present speaker recognition research. However, these
trivial events are highly valuable in some particular circumstances such as
forensic examination, as they are less subjected to intentional change, so can
be used to discover the genuine speaker from disguised speech. In this paper,
we collect a trivial event speech database that involves 75 speakers and 6
types of events, and report preliminary speaker recognition results on this
database, by both human listeners and machines. Particularly, the deep feature
learning technique recently proposed by our group is utilized to analyze and
recognize the trivial events, which leads to acceptable equal error rates
(EERs) despite the extremely short durations (0.2-0.5 seconds) of these events.
Comparing different types of events, 'hmm' seems more speaker discriminative.Comment: ICASSP 201
Efficient coding schemes for low‐rate wireless personal area networks
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166246/1/cmu2bf01608.pd
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