Physica B+C最新文献

A spectrometer for carrying out perfect crystal diffractometry and neutron interferometry is proposed to be set up at the new 100 MW research reactor Dhruva, as part of a programme to expand and upgrade neutron beam based research activities at the Bhabha Atomic Research Centre (BARC). At present a facility has been set up at the CIRUS reactor where interference oscillations have been recorded using a symmetric LLL silicon interferometer. The setup at CIRUS will serve as a test bed for development of interferometry in BARC.

40 years after Gabor's proposal of electron holography, electron image plane off-axis holography using the Möllenstedt type electron biprism is able to investigate the electron object wave by its amplitude and phase at atomic dimensions.

For didactic as well as historical reasons it does not make much sense for about thirty years to speak of the diffraction of electron waves by microscopic slits as an “imaginary experiment”.

The coherence length of electron waves has been measured by the phase shift of a coherent partial electron wave propagating through a metallic micro-tube to which an electric potential is applied.

The statement by H. Hora that the phase shift of electron waves due to the magnetic vector potential depends on electron velocity is not supported by experiments.

There is no principal upper limit for the electron-optical path length difference due to an enclosed magnetic flux.

An achromatic imaging instrument for neutrons of wavelengths larger than 1.2 nm is described. The measured resolution of 28.5 μm is not too far away from the ultimate limit of 6 μm calculated by wave mechanics.

A brief summarizing review is given of all those neutron interferometric experiments performed hitherto which explicitly use the spin-$\text{1}\text{2}$ particle properties of the neutron. It covers topics as the verification of the 4π-periodicity of spinors, the cooperative action of nuclear phase shift and spin-rotation on the neutron wave function, the demonstration of the quantum mechanical principles of fermion spin-state superposition and the more recent double resonance experiments where the two interfering beams propagate through spatially separated oscillatory magnetic fields. Finally a proposal will be presented also for a so-called “late-choice” experiment with polarized neutrons.

This paper describes our progress on a neutron interferometry search for the Aharonov-Casher (A-C) effect. Unpolarized neutrons are passed through a 40 kV/mm vacuum electrode system. The spin-dependent phase is set to maximum sensitivity with a magnetic field, and the spin-independent phase is adjusted to zero (modulo 2π) using the Earth's gravitational field. Upon reversal of the electric field, the predicted A-C phase shift is 0.2°. Currently, our results are statistically limited.

The methods we will describe are somewhat related to classical optics. They have been used at the research reactor in Munich and later at the Institute Laue-Langevin in Grenoble, helping to improve research in neutron scattering and in nuclear physics using neutrons.

The interaction of a single Rydberg atom with a single mode of the electromagnetic field and the resonance fluorescence of a single atomic ion stored in radio-frequency trap were investigated. In the former experiment, the quantum collapse and revival of the atomic inversion predicted by the Jaynes-Cummings model could be demonstrated for the first time. In the latter experiment, antibunching and sub-Poissonian photon statistics were detected in the fluorescent light. Furthermore the observation of the crystallization of few ions in a trap is described. Since the stored ions can be cooled by the laser light and heated by the radio frequency field of the trap, subsequent phase transitions could be observed.