Parity violation in Aharonov-Bohm systems: The spontaneous Hall effect

We show how macroscopic manifestations of P (and T) symmetry breaking can arise in a simple system subject to Aharonov-Bohm interactions. Specifically, we study the conductivity of a gas of charged particles moving through a dilute array of flux tubes. The interaction of the electrons with the flux tubes is taken to be of a purely Aharonov-Bohm type. We find that the system exhibits a nonzero transverse conductivity, i.e., a spontaneous Hall effect. This is in contrast to the fact that the cross sections for both scattering and bremsstrahlung (soft-photon emission) of a single electron from a flux tube are invariant under reflections. We argue that the asymmetry in the conductivity coefficients arises from many-body effects. On the other hand, the transverse conductivity has the same dependence on universal constants that appears in the quantum Hall effect, a result that we relate to the validity of the mean-field approximation.

Memorial exercises in honor of William Boyd Allison : in Hall of House of Representatives, State Capitol, Des Moines, Iowa, Tuesday, September 8, 1908

Program of the memorial in honor of William Boyd Allison, senior Senator of the State of Iowa, who died at his home in Dubuque, Iowa, August 4, 1908. It includes full text of remarks presented at the memorial by dignitaries in attendance.

Looking Back: Historical Hall, 1899-1904; State Historical, Memorial and Art Building, 1905-1999; Ola Babcock Miller Building, 1999-Present, June 2013

For more than 80 years, visitors to the Iowa State Historical, Memorial, and Art Building were treated to the state’s collection of historic documents, literature, portraits, and historical, geological, and archeological artifacts. Those who visited might have memories of the spectacular sand paintings by Iowan Andrew Clemens, the variety of taxidermy Iowa animals, the pioneer Conestoga wagon in the basement, the biplane hanging from the dome ceiling, the odd display by the medical library of things removed from stomachs, or the Native American display on the third floor. This booklet is a look back at the origins of the museum. It includes some of the Historical Department reports, legislation passed by the general assembly, newspaper and magazine articles, and photographs pertaining to the museum and library. It is not intended to be an exhaustive review and documentation of displays and exhibits. It is a brief overview of the building’s history and some photographs that may bring back memories, for some, of a field trip as a student. This booklet has been created from a variety of source materials: photographs, newspaper articles, and various reports. The following have contributed: State Library of Iowa, Iowa State Historical Society, the Iowa Judicial Branch, Susan Wallace, Helen Dagley, Barb Corson, Jerome Thompson, Pam Rees, Georgiann Fischer, and Jason Mrachina.

Oman aikansa Kiina-ilmiö : suomalaisten lähetyssaarnaajien kokemuksia länsimaisen ja kiinalaisen kulttuurin ja uskonnon kohtaamisesta 1900-luvun alussa

Zusammenfassung: Das China-Phänomen : über die Erfahrungen finnischer Missionsprediger bei der Begegnung westlicher und chinesischer Kultur und Religion Anfang des 20. Jahrhunderts

Quantum Hall Phases of two-component bosons

The recent production of synthetic magnetic fields acting on electroneutral particles, such as atoms or photons, has boosted interest in the quantum Hall physics of bosons. Adding pseudospin 1/2 to the bosons greatly enriches the scenario, as it allows them to form an interacting integer quantum Hall (IQH) phase with no fermionic counterpart. Here we show that, for a small two-component Bose gas on a disk, the complete strongly correlated regime, extending from the integer phase at filling factor ν = 2 to the Halperin phase at filling factor ν = 2 / 3, is well described by composite fermionization of the bosons. Moreover we study the edge excitations of the IQH state, which, in agreement with expectations from topological field theory, are found to consist of forward-moving charge excitations and backward-moving spin excitations. Finally, we demonstrate how pair-correlation functions allow one to experimentally distinguish the IQH state from competing states, such as non-Abelian spin singlet (NASS) states.

Topological phases in small quantum Hall samples

Topological order has proven a useful concept to describe quantum phase transitions which are not captured by the Ginzburg-Landau type of symmetry-breaking order. However, lacking a local order parameter, topological order is hard to detect. One way to detect it is via direct observation of anyonic properties of excitations which are usually discussed in the thermodynamic limit, but so far has not been realized in macroscopic quantum Hall samples. Here we consider a system of few interacting bosons subjected to the lowest Landau level by a gauge potential, and theoretically investigate vortex excitations in order to identify topological properties of different ground states. Our investigation demonstrates that even in surprisingly small systems anyonic properties are able to characterize the topological order. In addition, focusing on a system in the Laughlin state, we study the robustness of its anyonic behavior in the presence of tunable finite-range interactions acting as a perturbation. A clear signal of a transition to a different state is reflected by the system's anyonic properties.