Frequencies of the Edge-Magnetoplasmon Excitations in Gated Quantum Hall Edges

We have investigated microwave transmission through the edge of quantum Hall systems by employing a coplanar waveguide (CPW) fabricated on the surface of a GaAs/AlGaAs two-dimensional electron gas (2DEG) wafer. An edge is introduced to the slot region of the CPW by applying a negative bias $V_\mathrm{g}$ to the central electrode (CE) and depleting the 2DEG below the CE. We observe peaks attributable to the excitation of edge magnetoplasmons (EMP) at a fundamental frequency $f_0$ and at its harmonics $i f_0$ ($i$ = 2, 3,...). The frequency $f_0$ increases with decreasing $V_\mathrm{g}$, indicating that EMP propagates with higher velocity for more negative $V_\mathrm{g}$. The dependence of $f_0$ on $V_\mathrm{g}$ is interpreted in terms of the variation in the distance between the edge state and the CE, which alters the velocity by varying the capacitive coupling between them. The peaks are observed to continue, albeit with less clarity, up to the regions of $V_\mathrm{g}$ where 2DEG still remains below the CE.Comment: 8 pages, 8 figure

A massive disk galaxy at z>3 along the sightline of QSO 1508+5714

We have obtained deep images in the BVRIJHKs bands of the field centered on QSO 1508+5714 (z_{em} =4.28) with the Suprime camera, FOCAS and MOIRCS cameras on Subaru telescope. We report here the detection of a B-dropout galaxy, which is 3\secpoint 5 north-west of the QSO sightline. A photometric redshift analysis is presented to complement the color selection. Given the photometric properties of this object ($M = -22.2$, making $L\approx 3 L^{\ast}$, if placed at its photometric redshift $z\sim 3.5$), as well as the S$\acute{e}$rsic index ($n \sim 1$) derived from a 2-D imaging decomposition of the HST WFPC2 image taken in the $I_{F814}$ filter, the identified system is consistent with a massive disk galaxy at z>3. If confirmed, it would be one of the most distant massive disk galaxies known so far.Comment: 12 pages, 6 figures, accepted by PASJ, Vol.61/No.5, 200

Probing local electronic states in the quantum Hall regime with a side coupled quantum dot

We demonstrate a new method for locally probing the edge states in the quantum Hall regime utilizing a side coupled quantum dot positioned at an edge of a Hall bar. By measuring the tunneling of electrons from the edge states into the dot, we acquire information on the local electrochemical potential and electron temperature of the edge states. Furthermore, this method allows us to observe the spatial modulation of the electrostatic potential at the edge state due to many-body screening effect.Comment: 5 pages, 5 figure

IMPLEMENTASI METODE GLENN DOMAN UNTUK MENINGKATKAN KEMAMPUAN MEMBACA PERMULAAN PADA ANAK TUNARUNGU

Penelitian ini dilatar belakangi masih ada diantara siswa kelas III di SDLB ABCD Muhammadiyah Ciparay. Kab. Bandung yang masih belum dapat membaca dengan lancar dalam hal ini membaca permulaan. Penelitian ini difokuskan pada “ Implementasi metode Glenn Doman untuk meningkatkan kemampuan membaca permulaan pada anak tunarungu”. Metode ini dianggap sangat cocok untuk anak tunarungu, karena anak tunarungu sering dikatakan sebagai manusia pemata, dimana anak tunarungu bisa memfokuskan pembelajaranya lewat indera penglihatannya . Metode yang digunakan pada penelitian ini adalah eksperimen dengan subjek tunggal (SSR). Subyek penelitian adalah seorang siswa tunarungu kelas III SD di SDLB ABCD Muhammadiyah Kec. Ciparay Kab. Bandung. Berdasarkan hasil penelitian implementasi metode Glenn Doman memiliki dampak yang positif dalam meningkatkan kemampuan membaca permulaan pada subjek penelitian (R.A.F). Dimana mean level di setiap sesi terus meningkat, pada baseline 1 (A1) dilakukan dalam tiga sesi pada mean level 36,3%, intervensi (B) dilaksanakan sebanyak tujuh sesi pada mean level 59,9 % dan baseline 2 (A2) dilakukan sebanyak tiga sesi dan berada pada mean level 73,3 %. Maka disimpulkan bahwa penerapan metode Glenn Doman dapat meningkatkan kemampuan membaca permulaan . Peneliti dapat merekomendasikan bahwa metode Glenn Doman dapat menjadi salah satu metode alternatif ,yaitu metode yang dapat digunakan dalam pembelajaran membaca permulaan pada anak tunarungu, dengan subjek dan desain serta rancangan materi penelitian yang berbed

Interference Effect in Multi-level Transport through a Quantum Dot

We present experimental results and a model to solve the problem of "in-phase Coulomb peaks" observed in transport through a quantum dot. In a marginal region between Coulomb-blockade and open-dot, we have observed Fano-type interference through two energy levels inside the dot, which manifest themselves in two overlapped Coulomb-diamond-like structures in the excitation spectrum. One of the two levels is strongly coupled to the leads and the phase of traversing electrons is locked to it. We have detected the phase change at the vertices and the centers of the larger diamonds through the sign of the Fano's asymmetric parameters supporting the above deduction.Comment: 4 pages, 4 figures, to appear in J. Phys. Soc. Jpn. (December 15, 2004