8,010 research outputs found
Higgs amplitude mode in massless Dirac fermion systems
The Higgs amplitude mode in superconductors is the condensed matter analogy
of Higgs bosons in particle physics. We investigate the time evolution of Higgs
amplitude mode in massless Dirac systems, induced by a weak quench of an
attractive interaction. We find that the Higgs amplitude mode in the
half-filling honeycomb lattice has a logarithmic decaying behaviour,
qualitatively different from the decay in the normal
superconductors. Our study is also extended to the doped cases in honeycomb
lattice. As for the 3D Dirac semimetal at half filling, we obtain an undamped
oscillation of the amplitude mode. Our finding is not only an important
supplement to the previous theoretical studies on normal fermion systems, but
also provide an experimental signature to characterize the superconductivity in
2D or 3D Dirac systems.Comment: 6 pages, 8 figure
A Single-Phase Four-Switch Rectifier With Significantly Reduced Capacitance
A single-phase four-switch rectifier with considerably reduced capacitance is investigated in this paper. The rectifier consists of one conventional rectification leg and one neutral leg linked with two capacitors that split the dc bus. The ripple energy in the rectifier is diverted into the lower split capacitor so that the voltage across the upper split capacitor, designed to be the dc output voltage, has very small ripples. The voltage across the lower capacitor is designed to have large ripples on purpose so that the total capacitance needed is significantly reduced and highly reliable film capacitors, instead of electrolytic capacitors, can be used. At the same time, the rectification leg is controlled independently from the neutral leg to regulate the input current to achieve unity power factor and also to maintain the dc-bus voltage. Experimental results are presented to validate the performance of the proposed strategy
Stabilization of a Cascaded DC Converter System via Adding a Virtual Adaptive Parallel Impedance to the Input of the Load Converter
Connecting converters in cascade is a basic configuration of dc distributed power systems (DPS). The impedance interaction between individually designed converters may make the cascaded system become unstable. The previous presented stabilization approaches not only need to know the information of the regulated converter, but also have to know the characteristics of the other converters in the system, which are contradictory to the modularization characteristic of dc DPS. This letter proposes an adaptive-input-impedance-regulation (AIIR) method, which connects an adaptive virtual impedance in parallel with the input impedance of the load converter, to stabilize the cascaded system. This virtual impedance can adaptively regulate its characteristic for different source converters. Therefore, with the AIIR method, all the load converters can be designed to a fixed standard module to stably adapt various source converters. In addition, at any cases, the AIIR approach only changes the load converter's input impedance in a very small frequency range to keep the load converter's original dynamic performance. The requirements on the AIIR method are derived and the control strategies to achieve the AIIR method are proposed. Finally, considering the worst stability problem that often occurs at the system whose source converter is an LC filter, a load converter cascaded with two different LC input filters is fabricated and tested to validate the effectiveness of the proposed AIIR control method
Optical generation of hybrid entangled state via entangling single-photon-added coherent state
We propose a feasible scheme to realize the optical entanglement of
single-photon-added coherent state (SPACS) and show that, besides the Sanders
entangled coherent state, the entangled SPACS also leads to new forms of hybrid
entanglement of quantum Fock state and classical coherent state. We probe the
essential difference of two types of hybrid entangled state (HES). This HES
provides a novel link between the discrete- and the continuous-variable
entanglement in a natural way.Comment: 6 pages, 2 figure
Symplectic Geometry on Quantum Plane
A study of symplectic forms associated with two dimensional quantum planes
and the quantum sphere in a three dimensional orthogonal quantum plane is
provided. The associated Hamiltonian vector fields and Poissonian algebraic
relations are made explicit.Comment: 12 pages, Late
Dissipationless Layertronics in Axion Insulator
Surface electrons in axion insulators are endowed with a topological layer
degree of freedom followed by exotic transport phenomena, e.g., the layer Hall
effect [Gao et al., Nature 595, 521 (2021)]. Here, we propose that such a layer
degree of freedom can be manipulated in a dissipationless way based on the
antiferromagnetic with tailored domain structure. This makes
a versatile platform to exploit the "layertronics" to encode,
process, and store information. Importantly, the layer filter, layer valve, and
layer reverser devices can be achieved using the layer-locked chiral domain
wall modes. The dissipationless nature of the domain wall modes makes the
performance of the layertronic-devices superior to those in spintronics and
valleytronics. Specifically, the layer reverser, a layer version of Datta-Das
transistor, also fills up the blank in designing the valley reverser in
valleytronics. Our work sheds light on constructing new generation electronic
devices with high performance and low energy consumption in the framework of
layertronics.Comment: 7 pages, 4 figures (+Supplementary Materials: 5 pages, 6 figures
Phi Meson in Dense Matter
Journals published by the American Physical Society can be found at http://publish.aps.org/The effect of the kaon loop correction to the property of a phi meson in dense matter is studied in the vector dominance model. Using the density-dependent kaon effective mass determined from the linear chiral perturbation theory, we find that with increasing baryon density the phi meson mass is reduced slightly while its width is broadened drastically
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