Decomposition mechanism of triethylindium (TEI) on a GaP(0 0 1)-(2×1) surface studied by LEED, AES, TPD and HREELS

Adsorption and decomposition of triethylindium (TEI: (C₂H₅)₃In) on a GaP(0 0 1)-(2×1) surface have been studied by low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). It is found from the TPD result that ethyl radical and ethylene are evolved at about 300–400 and 450–550 K, respectively, as decomposition products of TEI on the surface. This result is quite different from that on the GaP(0 0 1)-(2×4) surface. The activation energy of desorption of ethyl radical is estimated to be about 93 kJ/mol. It is suggested that TEI is adsorbed molecularly on the surface at 100 K and that some of TEI molecules are dissociated into C₂H₅ to form P–C₂H₅ bonds at 300 K. The vibration modes related to ethyl group are decreased in intensity at about 300–400 and 450–550 K, which is consistent with the TPD result. The TEI molecules (including mono- and di-ethylindium) are not evolved from the surface. Based on the TPD and HREELS results, the decomposition mechanism of TEI on the GaP(0 0 1)-(2×1) surface is discussed and compared with that on the (2×4) surface.     

Demonstration of an optical quantum controlled-NOT gate without path interference

We report the first experimental demonstration of an optical quantum controlled-NOT gate without any path interference, where the two interacting path interferometers of the original proposals have been replaced by three partially polarizing beam splitters with suitable polarization dependent transmittance and reflectance. The performance of the device is evaluated using a recently proposed method, by which the quantum process fidelity and the entanglement capability can be estimated from the 32 measurement results of two classical truth tables, significantly less than the 256 measurement results required for full quantum tomography.     

Electrical properties of ferroelectric-gate FETs with SrBi2Ta2O9 formed using MOCVD technique

Ferroelectric-gate?field-effect?transistors?(FeFETs) with a Pt/SrBi₂Ta₂O₉/Hf-Al-O/Si gate stack were fabricated using the metal-organic chemical vapor deposition (MOCVD) technique to prepare the SrBi₂Ta₂O₉ (SBT) ferroelectric layer. A?good threshold voltage (V _th) distribution was found for more than 90?n-channel FeFETs in one chip with a 170?nm SBT layer owing to the good film uniformity of the SBT layer deposited by MOCVD. The average memory window $(V_{\mathrm{w}}^{\mathrm{av}})$ and the standard deviations (σ _thl,σ _thr) of the left- and right-side branches of the drain-gate voltage curves of the FeFETs yielded a $V_{\mathrm{w}}^{\mathrm{av}}/(\sigma_{\mathrm{thl}} + \sigma_{\mathrm{thr}})$ value of 5.45, indicating that the FeFETs can be adapted for large-scale-integration. The electric field, the energy band profile in the gate stack, and the gate leakage current were also investigated at high gate voltages. We found that the effect of Fowler–Nordheim tunneling appeared under these conditions. Because of the tunneling injection and trapping of electrons into the gate insulators, the operation voltage ranges of the FeFETs were limited by this tunneling.     

Mapping analyses of Fe-diffused mc-Si using M?ssbauer microscope and photoluminescence

Twenty CK chondrites collected in the Antarctica Continent were characterized by inductively-coupled plasma mass spectrometry (ICP-MS), prompt gamma ray analysis (PGA), instrumental neutron activation analysis (INAA), X-ray diffractometry (XRD) and ⁵⁷Fe-M?ssbauer spectroscopy. As a result of elemental analysis, it was revealed that 18.2~26.4 mass% of iron was included in the each chondrite. M?ssbauer spectrum of LEW86258, classified as a typical CK chondrite, was found to be composed of two paramagnetic doublets and two magnetic sextets. M?ssbauer spectra were assigned to the absorption due to forsterite (Mg_1.36Fe_0.64SiO₄) and magnetite (Fe₃O₄), as also confirmed by XRD. XRD study of LAP03834, reclassified from CK to R chondrite, revealed the presence of crystalline phase due to forsterite. These results indicate that LAP03834 and related chondrites, i.e., MET01149, LAP03923 and MAC02453, should be reclassified as R or LL chondrite.     

QCD perturbation theory in the temporal gauge

In this paper we present a non-trivial check of the consistency of the quantization of a gauge theory with fermions (QCD) in the temporal gauge. We use the approach based on the finite time Feynman propagation kernel, in which the Gauss law is imposed as a constraint on the states by means of a functional integration over all the time independent gauge transformations acting on the boundary values of the fields. We spell out in detail the “Feynman rules” when fermions are present and we compute, as an example, the gauge invariant correlation function $$\begin{gathered} G(t) = \left\langle {\bar \psi (0,t)(\gamma _5 \gamma _0 )\frac{{1 - \gamma _0 }}{2}P} \right. \hfill \\ \left. { \cdot \exp \left( {ig\int\limits_0^t {A_0 (0,t')dt'} } \right)(\gamma _5 \gamma _0 )^ + (0,0)} \right\rangle \hfill \\ \end{gathered} $$ up to orderg ², obtaining the expected result.     

CW Operation of a Submillimeter Wave Gyrotron (Gyrotron Fu IV) for High Stability of the Output Frequency

The first cw operation of our submillimeter wave gyrotron (Gyrotron FU IV) using a 12 T superconducting magnet has been successfully carried out. Output power is more than 20 W at a frequency of 301 GHz in the TE₀₃₁ resonant cavity mode. Time-resolved frequency measurement s shows that the frequency fluctuation of the gyrotron output is smaller than 2 MHz. This frequency fluctuation is mainly due to the fluctuation in the output voltage of the power supply.     

High Efficiency Electrically-Addressable Phase-Only Spatial Light Modulator

To realize a high efficiency electrically addressable phase-only modulator, we have coupled a liquid crystal display (LCD) to an optically addressed parallel-aligned nematic liquid crystal spatial light modulator (PAL-SLM) with a set of lenses. Phase modulation exceeding 3ϖ at 532 nm wavelength was obtained. We obtained linear transfer characteristics for phase modulation at various desired phase levels after calibration and adjustment of the transfer characteristics of the PAL-SLM and the LCD. Diffraction efficiency of 40% for binary phase grating and of 90% for 8-level blazed phase grating, which were very close to the simulation values, were observed. The power loss of the readout light was caused when passed through a half mirror, therefore, we examined a setup using an oblique readout light at the modulator. Very high diffraction efficiency was obtained from the setup by optimizing the polarization direction and optical path for this light, and the orientation of liquid crystals. Since the modulator can perform at better than 90% diffraction efficiency and at nearly 100% reflectivity, various high efficiency systems utilizing such modulators are expected.     

Development of frequency tunable, medium power gyrotrons (GyrotronFU series) as submillimeter wave radiation sources

High frequency, medium power gyrotrons (Gyrotron FU series) have been developed at Fukui University as radiation sources covering a broad band from millimeter to submillimeter wave region. They have already been applied to high frequency electron spin resonance and to submillimeter wave scattering in plasma. Many parameters of the gyrotron series could be useful for applications in several new areas. The development and some applications of the Gyrotron FU series are summarized in this paper     

Nonperturbative gadget for topological quantum codes

Many-body entangled systems, in particular topologically ordered spin systems proposed as resources for quantum information processing tasks, often involve highly nonlocal interaction terms. While one may approximate such systems through two-body interactions perturbatively, these approaches have a number of drawbacks in practice. In this Letter, we propose a scheme to simulate many-body spin Hamiltonians with two-body Hamiltonians nonperturbatively. Unlike previous approaches, our Hamiltonians are not only exactly solvable with exact ground state degeneracy, but also support completely localized quasiparticle excitations, which are ideal for quantum information processing tasks. Our construction is limited to simulating the toric code and quantum double models, but generalizations to other nonlocal spin Hamiltonians may be possible.