Magnetopolaron states involving confined phonons in a semiconductor quantum well

Energy splitting ΔE _res in double magnetopolaron energy spectrum in rectangular quantum wells as functions of the well width d have been calculated. We have considered in the capacity of interaction leading to resonant coupling between electrons and phonons the interaction with confined phonons and (for comparison) with bulk LO phonons. We have obtained the conditions when the interaction with bulk phonons yields correct results. Calculations for AlAs/GaAs/AlAs and AlSb/InSb/AlSb structures have been performed. Alongside the parameter ΔE _res for a polaron, whose resonant magnetic field is determined by the condition Ω=ω _L1, where Ω is the cyclotron frequency and ω _L1 is the LO phonon frequency in the quantum well (A-polaron), we have calculated ΔE _res for D-(Ω=2ω _L1) and F-polarons (Ω=3ω _L1), which is a factor of $\sqrt 2 $ and $\sqrt 3 $ , respectively, smaller than ΔE _res for the A-polaron. Since the splitting ΔE _res for the A-polaron is very large (up to 0.2?ω _L1), it is more convenient to study in experiments D-and F-polarons since their resonant magnetic fields are lower. We have predicted existence of “weak” magnetopolarons, in which the splitting is proportional to a higher power of Frölich’s coupling constant α than α ^1/2.     

Majorana edge states in interacting one-dimensional systems

We show that one-dimensional electron systems in the proximity of a superconductor that support Majorana edge states are extremely susceptible to electron-electron interactions. Strong interactions generically destroy the induced superconducting gap that stabilizes the Majorana edge states. For weak interactions, the renormalization of the gap is nonuniversal and allows for a regime in which the Majorana edge states persist. We present strategies of how this regime can be reached.     

Measurement of the neutrino mass splitting and flavor mixing by MINOS

Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of 7.25×10(20) protons on target. A fit to neutrino oscillations yields values of |Δm(2)|=(2.32(-0.08)(+0.12))×10(-3) eV(2) for the atmospheric mass splitting and sin(2)(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.     

Measurement of an Efimov trimer binding energy in a three-component mixture of 6Li

The binding energy of an Efimov trimer state was precisely determined via radio-frequency association. It is found that the measurement results shift significantly with temperature, but that the shift becomes negligible at the lowest temperature in our experiment. The shift-free part of the trimer binding energy reveals a significant deviation from the nonuniversal theory prediction based on a three-body parameter with a monotonic binding-energy dependence.     

Experimental investigation of harmonic and subharmonic synchronization of 40 GHz mode-locked quantum-dash laser diodes

Synchronization of a 40 GHz quantum-dash mode-locked (ML) Fabry-Perot laser diode with optically injected pulse streams is experimentally studied. Injected signals consist of nonmodulated and modulated trains of 1.6 ps pulses at various repetition rates, ranging from 10 to 160 GHz and 10 to 160 Gbps, respectively. Subharmonic, fundamental, and harmonic synchronization of the ML laser allows retrieval of stable 40 GHz clock pulses featuring a width of 1.8 ps. Frequency components at 10 and 20 GHz do not create any amplitude modulation on the recovered 40 GHz clock pulses when injecting signals at 10 and 20 GHz/Gbps. In addition, external synchronization of the laser with pulse streams at 80 and 160 GHz/Gbps is sustained despite the absence of significant components at or below 40 GHz.     

Dark matter results from 100 live days of XENON100 data

We present results from the direct search for dark matter with the XENON100 detector, installed underground at the Laboratori Nazionali del Gran Sasso of INFN, Italy. XENON100 is a two-phase time-projection chamber with a 62 kg liquid xenon target. Interaction vertex reconstruction in three dimensions with millimeter precision allows the selection of only the innermost 48 kg as the ultralow background fiducial target. In 100.9 live days of data, acquired between January and June 2010, no evidence for dark matter is found. Three candidate events were observed in the signal region with an expected background of (1.8 ± 0.6) events. This leads to the most stringent limit on dark matter interactions today, excluding spin-independent elastic weakly interacting massive particle (WIMP) nucleon scattering cross sections above 7.0 × 10(-45) cm(2) for a WIMP mass of 50 GeV/c(2) at 90% confidence level.     

MRI investigation of granular interface rheology using a new cylinder shear apparatus

The rheology of granular materials near an interface is investigated through proton magnetic resonance imaging. A new cylinder shear apparatus has been inserted in the magnetic resonance imaging device, which allows the control of the radial confining pressure exerted by the outer wall on the grains and the measurement of the torque on the inner shearing cylinder. A multi-layer velocimetry sequence has been developed for the simultaneous measurement of velocity profiles in different sample zones, while the measurement of the solid fraction profile is based on static imaging of the sample. This study describes the influence of the roughness of the shearing interface and of the transverse confining walls on the granular interface rheology.     

一种新颖结构的高温超导信道滤波器设计

文章提出了一种新颖结构的高温超导信道滤波器设计方法,采用Sonnet软件进行微带电路的全波电磁场仿真.设计了一个一分二的高温超导信道滤波器,信道滤波器工作在S波段,每个信道的相对带宽约为0.4‰,采用的材料为多源热共蒸发法制备的DyBCO双面超导薄膜,衬底为0.5mm厚度的氧化镁.本文给出了本信道滤波器的等效电路、理论曲线、耦合参数和模拟仿真结果.     

Symmetry reduction and exact solutions of the (3+1)-dimensional Zakharovben Kuznetsov equation

By means of the classical method, we investigate the (3+1)-dimensional Zakharov-Kuznetsov equation. The symmetry group of the (3+1)-dimensional Zakharov-Kuznetsov equation is studied first and the theorem of group invariant solutions is constructed. Then using the associated vector fields of the obtained symmetry, we give the one-, two-, and three-parameter optimal systems of group-invariant solutions. Based on the optimal system, we derive the reductions and some new solutions of the (3+1)-dimensional Zakharov-Kuznetsov equation.