Low-Voltage High-Linearity Wideband Current Differencing Transconductance Amplifier and Its Application on Current-Mode Active Filter

A low-voltage high-linearity wideband current differencing transconductance amplifier (CDTA) is presented in this paper. The CDTA consists of a current differencing circuit and a cross-coupling transconductance circuit. The PSPICE simulations of the proposed CDTA show a good performance: -3dB frequency bandwith is about 900 MHz, low power consumption is 2.48 mW, input current linear range is ±100 µA and low current-input resistance is less than 20 Ω, high current-output resistance is more than 3 MΩ. PSpice simulations for a current-mode universal filter and a proposed high-order filter are also conducted, and the results verify the validity of the proposed CDTA

Periodicities in the occurrence of aurora as indicators of solar variability

A compilation of records of the aurora observed in China from the Time of the Legends (2000 - 3000 B.C.) to the mid-18th century has been used to infer the frequencies and strengths of solar activity prior to modern times. A merging of this analysis with auroral and solar activity patterns during the last 200 years provides basically continuous information about solar activity during the last 2000 years. The results show periodicities in solar activity that contain average components with a long period (approx. 412 years), three middle periods (approx. 38 years, approx. 77 years, and approx. 130 years), and the well known short period (approx. 11 years)

Spin squeezing: transforming one-axis-twisting into two-axis-twisting

Squeezed spin states possess unique quantum correlation or entanglement that are of significant promises for advancing quantum information processing and quantum metrology. In recent back to back publications [C. Gross \textit{et al, Nature} \textbf{464}, 1165 (2010) and Max F. Riedel \textit{et al, Nature} \textbf{464}, 1170 (2010)], reduced spin fluctuations are observed leading to spin squeezing at -8.2dB and -2.5dB respectively in two-component atomic condensates exhibiting one-axis-twisting interactions (OAT). The noise reduction limit for the OAT interaction scales as $\propto 1/{N^{2/3}}$, which for a condensate with $N\sim 10^3$ atoms, is about 100 times below standard quantum limit. We present a scheme using repeated Rabi pulses capable of transforming the OAT spin squeezing into the two-axis-twisting type, leading to Heisenberg limited noise reduction $\propto 1/N$, or an extra 10-fold improvement for $N\sim 10^3$.Comment: 4 pages, 3 figure

Conformal or Walking? Monte Carlo renormalization group studies of SU(3) gauge models with fundamental fermions

Strongly coupled gauge systems with many fermions are important in many phenomenological models. I use the 2-lattice matching Monte Carlo renormalization group method to study the fixed point structure and critical indexes of SU(3) gauge models with 8 and 12 flavors of fundamental fermions. With an improved renormalization group block transformation I am able to connect the perturbative and confining regimes of the N_f=8 flavor system, thus verifying its QCD-like nature. With N_f=12 flavors the data favor the existence of an infrared fixed point and conformal phase, though the results are also consistent with very slow walking. I measure the anomalous mass dimension in both systems at several gauge couplings and find that they are barely different from the free field value.Comment: 26 pages, 11 figure

Temperature - pressure phase diagram of the superconducting iron pnictide LiFeP

Electrical-resistivity and magnetic-susceptibility measurements under hydrostatic pressure up to p = 2.75 GPa have been performed on superconducting LiFeP. A broad superconducting (SC) region exists in the temperature - pressure (T-p) phase diagram. No indications for a spin-density-wave transition have been found, but an enhanced resistivity coefficient at low pressures hints at the presence of magnetic fluctuations. Our results show that the superconducting state in LiFeP is more robust than in the isostructural and isoelectronic LiFeAs. We suggest that this finding is related to the nearly regular [FeP_4] tetrahedron in LiFeP.Comment: 4 pages, 4 figure