Response Function of the Fractional Quantized Hall State on a Sphere II: Exact Diagonalization

We study the excitation spectra and the dynamical structure factor of quantum Hall states in a finite size system through exact diagonalization. Comparison is made between the numerical results so obtained and the analytic results obtained from a modified RPA in the preceding companion paper. We find good agreement between the results at low energies.Comment: 22 pages (REVTeX 3.0). 10 figures available on request. Complete postscript file (including figures) for this paper are available on the World Wide Web at http://cmtw.harvard.edu/~simon/ ; Preprint number HU-CMT-94S0

Composite Fermions with Orbital Magnetization

For quantum Hall systems, in the limit of large magnetic field (or equivalently small electron band mass $m_b$), the static response of electrons to a spatially varying magnetic field is largely determined by kinetic energy considerations. This response is not correctly given in existing approximations based on the Fermion Chern-Simons theory of the partially filled Landau level. We remedy this problem by attaching an orbital magnetization to each fermion to separate the current into magnetization and transport contributions, associated with the cyclotron and guiding center motions respectively. This leads to a Chern-Simons Fermi liquid description of the $\nu=\frac{1}{2m}$ state which correctly predicts the $m_b$ dependence of the static and dynamic response in the limit $m_b \rightarrow 0$.Comment: 4 pages, RevTeX, no figure

Kemungkinan Kehadiran Sistiserkus/cacing taenia saginata taiwanensis di Bali

Telah dilakukan suatu penelitian pendahuluan untuk mengetahui kemungkinan adanya sistiserkus atau cacing Taenia saginata taiwanensis di Bali. Pengamatan dilakukanterhadap adanya infeksi sistiserkus secara alami pada hati 638 ekor babi yang dipotong di RPH Denpasar , dari bulan Juni sampai Juli 1993.Bintik-bintik kecil kekuningan atau putih susu, yang diduga merupakan kista T.s. taiwanensis, ditemukan pada 146 hati babi (22,88%). Setiap hati yang terinfeksi mengandung 1 - 6 kista, yang menyebar secara acak di masing-masing lobus. Kebanyakan kista yang ditemukan telah mengalami degenerasi (66.43%) atau kalsifikasi (32.8%). Satu kista mature yang ditemukan (0.7%) dari hati yang positif, ternyata mengandung skoleks taenia yang diperlengkapi dengan kait-kait. Temuan ini menunjukkan kemungkinan adanya sisteserkus cacing Ts. taiwanensis di Bali sebab hati babi bukanlah tempat predileksi utama sistiserkus cacing Taenia solium

Dirofilaria Immitis (Leidy, 1856) dalam Jantung Anjing yang Diseksi di Fakultas Kedokteran Hewan Institut Pertanian Bogor

Di dalam ventrikel kanan jantung anjing berbagai ras yang diseksi di laboratorium Patologi Fakultas kedokteran Hewan Institut Pertanian Bogor sejak awal 1970-an hingga tahun 1993 acap kali ditemukan cacing Dirojilaria immitis. Cacing-cacing tersebut berwarna putih, panjang, langsing dengan mulut tanpa bibir. Usofagus yang pendek terdiri atas dua bagian yaitu bagian anterior yang muskuler dan bagian posterior yang glanduler. Cacing betina panjangnya 20 - 29 cm dengan rataan 24,1 cm mempunyai ekor yang lurus dan berujung tumpul; vulvanya terletak di belakang ujung posterior usofagus. Cacing jantan panjangnya 14 - 20 cm dengan rataan 16,7 cm mempunyai ekor yang melingkar membentuk spiral yang dilengkapi lateral alae yang sempit; mempunyai dua spikulum yang asilnetrik tanpa bursa kopulatriks maupun gubernakulum. Didekat ujung ekor terdapat enam buah papila kaudal yang berbentuk kerucut

Boundary degrees of freedom in fractional quantum Hall effect: Excitations on common boundary of two samples

Using the Carlip's method we have derived the boundary action for the fermion Chern-Simons theory of quantum Hall effects on a planar region with a boundary. We have computed both the bulk and edge responses of currents to the external electric field. From this we obtain the well-known anomaly relation and the boundary Hall current without introducing any ad hoc assumptions such as the chirality condition. In addition, the edge current on the common boundary of two samples is found to be proportional to the difference between Chern-Simons coupling strengths.Comment: 20 pages, uses revte

Precision Astrometry of a Sample of Speckle Binaries and Multiples with the Adaptive Optics Facilities at the Hale and Keck II Telescopes

Using the adaptive optics facilities at the 200-in Hale and 10-m Keck II, we observed in the near infrared a sample of 12 binary and multiple stars and one open cluster. We used the near diffraction limited images of these systems to measure the relative separations and position angles between their components. In this paper, we investigate and correct for the influence of the differential chromatic refraction and chip distortions on our relative astrometric measurements. Over one night, we achieve an astrometric precision typically well below 1 miliarcsecond and occasionally as small as 40 microarcseconds. Such a precision is in principle sufficient to astrometrically detect planetary mass objects around the components of nearby binary and multiple stars. Since we have not had sufficiently large data sets for the observed sample of stars to detect planets, we provide the limits to planetary mass objects based on the obtained astrometric precision.Comment: 18 pages, 8 figures, 9 tables, to appear in MNRA

Precision characterisation of two-qubit Hamiltonians via entanglement mapping

We show that the general Heisenberg Hamiltonian with non-uniform couplings can be characterised by mapping the entanglement it generates as a function of time. Identification of the Hamiltonian in this way is possible as the coefficients of each operator control the oscillation frequencies of the entanglement function. The number of measurements required to achieve a given precision in the Hamiltonian parameters is determined and an efficient measurement strategy designed. We derive the relationship between the number of measurements, the resulting precision and the ultimate discrete error probability generated by a systematic mis-characterisation, when implementing two-qubit gates for quantum computing.Comment: 6 Pages, 3 figure

Composite-Fermion Picture for the Spin-Wave Excitation in the fractional quantum Hall system

Spin-wave excitation mode from the spin-polarized ground state in the fractional quantum Hall liquid with odd fractions ($\nu=1/3,1/5$) numerically obtained by the exact diagonalization of finite systems is shown to be accurately described, for wavelengths exceeding the magnetic length, in terms of the composite-fermion mean-field approximation for the spin-wave (magnon) theory formulated in the spherical geometry. This indicates that the composite picture extends to excited states, and also provides the spin stiffness in terms of peculiar exchange interactions.Comment: 10 pages, typeset in LATEX, NA-94-05, 2 figures available upon request at [email protected]

Influence of gauge-field fluctuations on composite fermions near the half-filled state

Taking into account the transverse gauge field fluctuations, which interact with composite fermions, we examine the finite temperature compressibility of the fermions as a function of an effective magnetic field $\Delta B = B - 2 n_e hc/e$ ($n_e$ is the density of electrons) near the half-filled state. It is shown that, after including the lowest order gauge field correction, the compressibility goes as ${\partial n \over \partial \mu} \propto e^{- \Delta \omega_c / 2 T} \left ( 1 + {A (\eta) \over \eta - 1} {(\Delta \omega_c)^{2 \over 1 + \eta} \over T} \right )$ for $T \ll \Delta \omega_c$, where $\Delta \omega_c = {e \Delta B \over mc}$. Here we assume that the interaction between the fermions is given by $v ({\bf q}) = V_0 / q^{2 - \eta} \ (1 \le \eta \le 2)$, where $A (\eta)$ is a $\eta$ dependent constant. This result can be interpreted as a divergent correction to the activation energy gap and is consistent with the divergent renormalization of the effective mass of the composite fermions.Comment: Plain Tex, 24 pages, 5 figures available upon reques