Abstract ：

The growth rate of the out-of-time-ordered correlator in a N-flavor Fermi gas is investigated and the Lyapunov exponent lambda(L) is calculated to the order of 1/N. We find that the Lyapunov exponent monotonically increases as the interaction strength increases from the BCS limit to the unitary region. At the unitarity, the Lyapunov exponent increases while the temperature drops and it can reach to the order of lambda(L)similar to T around the critical temperature for the N = 1 case. For N -> infinity, the Lyapunov exponent reaches its maximum lambda(L) approximate to 4.35T/N at the critical temperature. The system scrambles faster for stronger pairing fluctuations. At the BCS limit, the Lyapunov exponent behaviors as lambda(L) proportional to e(mu/T)a(s)(2)T(2)/N.

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The electrical method for measuring junction temperature inhomogeneity of IGBT modules has always been a scientific research problem in the field of microelectronics. This paper proposes a new type of electrical method for measuring junction temperature inhomogeneity, which is different from the conventional electrical methods using a single test condition. The collector currents measured in this paper are at high and low gate voltage, respectively. Based on the temperature calibration curve and the IGBT chips parallel model, the junction temperature inhomogeneity of the double-chip IGBT modules was analyzed successfully, and the junction temperature of the two chips were obtained respectively. © 2020 IEEE.

Keyword ：

Microelectronics Microelectronics Electron devices Electron devices Insulated gate bipolar transistors (IGBT) Insulated gate bipolar transistors (IGBT) Electric variables measurement Electric variables measurement

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We propose to generate localized artificial magnetic fields using two thin Raman laser beams intersected at a narrow region of a two-leg ladder, where the frequency difference must approximately match the energy offset between the two legs. Based on this method, we investigate the single-atom transport in a two-leg ladder with only two rungs, which, together with the legs, enclose a localized artificial magnetic flux. Here, the atoms on the two legs (channels) possess different onsite energies that produce another energy offset. We find that the atom incoming from the left channel can experience from blockade to transparency via modifying the onsite energy, tunneling strength, or magnetic flux, which can be potentially used for a quantum switcher. Furthermore, the atom incoming from the left channel can also be perfectly routed into the right leg, when, intriguingly, the outgoing atom in the right channel possesses a quasimomentum that can be modulated by the magnetic flux. The result may be potentially used for the interface that controls the communication between two individual quantum devices of cold atoms. The method can also be generalized to other artificial quantum systems, such as superconducting quantum circuit systems, optical systems, etc. © 2020 authors. Published by the American Physical Society.

Keyword ：

Laser beams Laser beams Magnetic fields Magnetic fields Magnetic flux Magnetic flux Atoms Atoms Quantum theory Quantum theory

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This paper proposes a novel method for online junction temperature measurement of silicon carbide metaloxide-semiconductor field-effect transistors (SiC MOSFETs). The measurement method is using the miller plateau voltage (VGS) and source leakage current (IDS) at transient inrush currents during turn-on process that based on the temperaturesensitive electrical parameters measurement method (TSEP). The comparison of infrared temperature measurement results shows that this method can provide more accurate junction temperature results and also can be used for transient junction temperature measurement in SiC MOSFET devices. It solves the problem that the traditional temperature-sensitive electrical parameter measurement method is difficult to measure the transient temperature rise. Finally, the results show that the use of VGS and IDS can provide more accurate junction temperature results which can be used for transient junction temperatures in SiC MOSEFT devices. © 2020 IEEE.

Keyword ：

Leakage currents Leakage currents Parameter estimation Parameter estimation Temperature measurement Temperature measurement Power quality Power quality Electric variables measurement Electric variables measurement Semiconductor junctions Semiconductor junctions Wide band gap semiconductors Wide band gap semiconductors Semiconducting silicon compounds Semiconducting silicon compounds MOSFET devices MOSFET devices Transients Transients Silicon carbide Silicon carbide MOS devices MOS devices Electric network parameters Electric network parameters

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We theoretically investigate the thermal-transport properties of a unitary Fermi gas between two reservoirs connected by a quantum point contact. We find several distinguished properties that are qualitatively different from those of weak or noninteracting gas systems. The particle transport figure of merit is drastically enhanced in the unitary regime. The Lorentz number violates the Wiedemann-Franz law, demonstrating the breakdown of Fermi liquid. These transport properties are the hallmarks of the unitary Fermi gas and are attributed to the existence of preformed Cooper pairs. The variation of the thermal-transport coefficients due to the changing of the transmission coefficient is also studied.

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Recent advances in experimental techniques allow one to create a quantum point contact between two Fermi superfluids in cold atomic gases with a tunable transmission coefficient. In this Rapid Communication we propose that three distinct behaviors of charge transports between two Fermi superfluids can be realized in this single setup, which are the multiple Andreev reflection, the self-trapping, and the Josephson oscillation. We investigate the dynamics of atom number difference between two reservoirs for different initial conditions and different transmission coefficients, and present a coherent picture of how the crossover between different regimes takes place. Our results can now be directly verified in the current experimental system.

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In RBF neural networks, the basis functions of hidden layers are often clustered by K-means algorithm. However, due to the K-means algorithm's dependence on the initial cluster center, it is too sensitive to noisy data. This paper proposes an RBF neural network based on K-nearest neighbors optimized clustering algorithm by fast search and finding the density peaks of a dataset(KNN-DPC). First, the optimized KNN-DPC algorithm is used to cluster data with too many noisy points, then the basis function center of RBF neural network is obtained, finally, the RBF neural network is constructed. The accuracy of this algorithm is verified by simulation experiments, and the results show that the algorithm is effective and practical.

Keyword ：

fast search and finding the density peaks of a dataset fast search and finding the density peaks of a dataset KNN-DPC algorithm KNN-DPC algorithm RBF neural network RBF neural network Noise data sensitivity Noise data sensitivity

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In RBF neural networks, the basis functions of hidden layers are often clustered by K-means algorithm. However, due to the K-means algorithm's dependence on the initial cluster center, it is too sensitive to noisy data. This paper proposes an RBF neural network based on K-nearest neighbors optimized clustering algorithm by fast search and finding the density peaks of a dataset(KNN-DPC). First, the optimized KNN-DPC algorithm is used to cluster data with too many noisy points, then the basis function center of RBF neural network is obtained, finally, the RBF neural network is constructed. The accuracy of this algorithm is verified by simulation experiments, and the results show that the algorithm is effective and practical. © 2018 IEEE.

Keyword ：

Learning algorithms Learning algorithms Radial basis function networks Radial basis function networks Multilayer neural networks Multilayer neural networks Information systems Information systems Information use Information use Functions Functions K-means clustering K-means clustering Computer aided instruction Computer aided instruction Nearest neighbor search Nearest neighbor search

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Abstract ：

A dual-band low noise amplifier (DBLNA), which can operate at 2.4 GHz and 5.8 GHz, is designed and realized. Infineon BFP740 SiGe HBTs are chose as active device, the cascode structure with high isolation and wider bandwidth is selected as gain circuit stage, whose bias current is selected to obtain minimum noise figure. In order to cope with the error of board technology and the PCB transmission loss, an additional stage is added into the cascode amplifier stage, both the peaking inductor and the RC circuit are utilized to compensate the decrease of high-frequency gain. A voltage divider circuit by resistor is employed to provide bias current, and the bias point is determined by scanning IB-NF. For the sake of miniaturization and adjustability, the π-type micro-strip line is used to achieve input/output matching. The combination of the electromagnetic simulation and the schematic diagram simulation, so-called co-simulation, is used to guarantee the simulation results are close to actual case. Finally the board-level layout is designed and the DBLNA PCB is fabricated and measured. © 2014 WIT Press.

Keyword ：

Printed circuit boards Printed circuit boards Noise figure Noise figure Schematic diagrams Schematic diagrams Amplifiers (electronic) Amplifiers (electronic) Low noise amplifiers Low noise amplifiers Voltage dividers Voltage dividers Heterojunction bipolar transistors Heterojunction bipolar transistors

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A low noise amplifier with dB-linear variable gain has been designed and fabricated based on high performance SiGe HBT in this paper. Negative feedback technology has been adopted to change the transmission gain of HBT through variable resistance of a forward biased p-i-n diode in the feedback path. The simulation results and measurement results agree well in frequency of 1.8GHz for CDMA application. A dynamic gain control of 14 dB in a control voltage range of 0.6-3.0 V has been achieved through the controllable feedback of the p-i-n diode. The noise figure was always lower than 5.5dB when the controlled voltage changed and the minimum noise figure is about 2.6dB. Both input matching and output matching maintained constants under all controlled voltage points. © 2011 CJMW.

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