We propose the first type I proof of the electric Aharonov-Bohm effect with hydrogen in a modified version of the ion interferometer realised by Hasselbach et al. The design of the setup is based on a coherent field emission single atom tip (SAT) source, a biprism beam splitter and a delay-line detector. Our calculations demonstrate, that the higher mass and therefore lower velocity of the ions compared to electrons combined with the high expected SAT ion emission puts the experiment into reach of current technical possibilities. A scheme for a large beam separation consisting of two biprism and a focussing lens is applied to introduce two metal cylinders in the beam paths that can be set on different potentials. The high detection time resolution allows to work with a continuous ion beam and circumvents the pulsed beam operation as suggested by Aharonov and Bohm. The setup can also be applied to test the influence of the ions internal structure in the magnetic Aharonov-Bohm effect in comparison to the point-shaped electrons.
We propose the first type I proof of the electric Aharonov-Bohm effect with hydrogen in a modified version of the ion interferometer realised by Hasselbach et al. The design of the setup is based on a coherent field emission single atom tip (SAT) source, a biprism beam splitter and a delay-line detector. Our calculations demonstrate, that the higher mass and therefore lower velocity of the ions compared to electrons combined with the high expected SAT ion emission puts the experiment into reach of current technical possibilities. A scheme for a large beam separation consisting of two biprism and a focussing lens is applied to introduce two metal cylinders in the beam paths that can be set on different potentials. The high detection time resolution allows to work with a continuous ion beam and circumvents the pulsed beam operation as suggested by Aharonov and Bohm. The setup can also be applied to test the influence of the ions internal structure in the magnetic Aharonov-Bohm effect in comparison to the point-shaped electrons.
The Aharonov-Bohm effect was first proposed in 1959, and has stimulated discussion and controversy since the start. Seen by many as a purely quantum mechanical effect, it nevertheless involves such issues as gauge invariance and relativistic dynamics. This multi-faceted nature has led it to be considered a keystone of modern quantum theory. Over the past half-century, interest has remained strong in what many believe is still an open debate as to the purely quantum nature. Additionally, discovery of similar effects for particles other than electrons has further driven curiosity. To better understand the issues such as electromagnetic mass and relativistic effects involved in the Aharonov-Bohm effect, a theoretical study of a simpler two particle system was done. The goal was to understand the manner in which mass of the system behaved strictly classically as compared to a relativistically. As a result of this, a Gedanken experiment is presented which serves as a test for covariance. The two particle system was extended to a spherical shell interacting with a single particle, and a second thought experiment put forth to explore a coupling between electromagnetism and gravitation. In the course of searching for simpler systems which involved the same issues as the Aharonov-Bohm effect, a system presented in the Feynman Lectures of Physics was found to be appropriate. We conduct a complete relativistic analysis of this system as a step towards a full relativistic analysis of the Aharonov-Bohm effect. Given the history and significance of the Aharonov-Bohm effect, it is perhaps surprising that relevant experimental tests had not been completed. For the first time, we searched for time delays as an electron passes a macroscopic solenoid. Such time delays are characteristic of classical forces acting on the electron. No such delays were found, seemingly confirming the standard viewpoint. It is still possible a classical explanation may exist for microscopic solenoids, though our experiment has served to place an upper limit for any such explanation. The definitive experiment concerning the Aharonov-Bohm Effect has yet to be completed. Proposed by Zeilinger, it consists of showing the dispersionless nature of the effect. To accomplish this requires an electron interferometer capable of enclosing a larger area and operating at lower energies than any which currently exist. We are attempting to construct such an interferometer using a hybrid approach with a nanofabricated grating and electron bi-prism. We have shown that experimentally that this combination can produce a large beam separation and still retain sufficient coherence to function as an interferometer.
Since the advent of quantum mechanics and the idea that massive particles exhibit wave properties, physicists have made efforts to make use of the short deBroglie wave length of matter waves for fundamental as well as practical studies. Among these are the precise measurements allowed by interference, diffraction, and microscopy as well as the study of more fundamental aspects of quantum theory such as the Aharonov-Bohm effects or the Stern-Gerlach effect, which are described below. However, in order to use matter waves to observe any of these effects it is necessary to produce and maintain coherence in the waves which are used for measurement. With a grasp of what coherence is and how it may be achieved and maintained one can move forward to study the interesting phenomena associated with coherent matter waves. More specifically in this work the interference and diffraction of electron matter waves are considered. The phenomena under consideration are those associated with the interaction of the electric charge and magnetic dipole moment of the electron with external fields and potentials while in the process of interfering or diffracting. Namely the focus of this dissertation is the Aharonov-Bohm effect, the Aharonov-Casher effect, and the Stern-Gerlach effect. Additionally, a wide-angle electron beam-splitter capable of producing two centimeter beam separation at the detection plane is discussed. The beam-splitter utilizes a nanofabricated periodic grating in combination with a bi-prism element. Contrary to devices utilizing only bi-prism elements, the use of the periodic grating causes amplitude, and not wave front, splitting. Even at maximum separation, beam profiles remain undistorted, providing evidence that coherence is intact. This is a step towards the realization of a large area electron interferometer using such a grating bi-prism combination. Such an interferometer could, in principle, be used to test the dispersionless nature of the Aharonov-Bohm effect. Work towards such an interferometer and possible future work are also discussed. Advisor: Herman Batelaan
The Aharonov–Bohm (AB) effect in the photodetachment microscopy of the H− ions in an electric field has been studied on the basis of the semiclassical theory. After the H− ion is irradiated by a laser light, they provide a coherent electron source. When the detached electron is accelerated by a uniform electric field, two trajectories of a detached electron which run from the source to the same point on the detector, will interfere with each other and lead to an interference pattern in the photodetachment microscopy. After the solenoid is electrified beside the H− ion, even though no Lorentz force acts on the electron outside the solenoid, the photodetachment microscopy interference pattern on the detector is changed with the variation in the magnetic flux enclosed by the solenoid. This is caused by the AB effect. Under certain conditions, the interference pattern reaches the macroscopic dimensions and could be observed in a direct AB effect experiment. Our study can provide some predictions for the future experimental study of the AB effect in the photodetachment microscopy of negative ions.
Temporal optics revolutionize the field of ultrafast detection with time-lens and time-stretch schemes. We developed a temporal interferometer that enables us to measure ultrafast phase shifts. With this interferometer, we measured phase shifts of correlated beams traveling in different temporal trajectories. This allows us to demonstrate the Aharonov-Bohm effect in the time domain. We developed the theoretical basis of this temporal Aharonov-Bohm effect and showed it in experimental measurements. In the talk, we will explain this effect, describe the experimental setup, and show the results.
A general challenge in various quantum experiments and applications is to develop suitable sources for coherent particles. In particular, recent progress in microscopy, interferometry, metrology, decoherence measurements and chip based applications rely on intensive, tunable, coherent sources for free low energy electron matter waves. In most cases, the electrons get field emitted from a metal nanotip where its radius and geometry towards a counter electrode determines the field distribution and the emission voltage. A higher emission is often connected to faster electrons with smaller de Broglie wavelengths, requiring larger pattern magnification after matter wave diffraction or interferometry. This can be prevented with a well-known setup consisting of two counter electrodes that allow independent setting of the beam intensity and velocity. However, it needs to be tested if the coherent properties of such a source are preserved after the acceleration and deceleration of the electrons. Here, we study the coherence of the beam in a biprism interferometer with a single atom tip electron field emitter if the particle velocity and wavelength varies after emission. With a Wien filter measurement and a contrast correlation analysis we demonstrate that the intensity of the source at a certain particle wavelength can be enhanced up to a factor of 33 without changing the transverse and longitudinal coherence of the electron beam. In addition, the energy width of the single atom tip emitter was measured to be 377 meV, corresponding to a longitudinal coherence length of 82 nm. The design has potential applications in interferometry, microscopy and sensor technology