Antiproton Interferometry and Aharonov–Bohm Effect (AIABE)
Andrey Alexandrov, Takashi Asada, Matías Bayo, Marco Beleggia, F. Castelli, Nicola D’Ambrosio, G. De Lellis, R. Ferragut, Stefano Frabboni, Alberto Galanti, Gian Carlo Gazzadi, Marco G. Giammarchi, Vincenzo Grillo, Marco Leali, G. Maero, V. Mascagna, Simone Masci, S. Migliorati, Fabio Mombelli, Tatsuhiro Naka, Massimiliano Romé, Giovanni Roncoli, Valeri E. Tioukov, V. Toso, L. Venturelli
The Aharonov–Bohm (AB) effect is one of the most striking features of quantum physics, and it is of critical importance to elucidate the role of the electromagnetic potential and its physical meaning. In spite of the fact that it was first proposed in 1949, up to now it has only been demonstrated for electrons and neutrons. We propose the realization of an experiment to study the AB effect for the antiproton, which will have the double feature of being a non-elementary charged particle and at the same time an antiparticle. The experiment will be conducted in collaboration with the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) group at the CERN AD (Antiproton Decelerator), making use of a slow antiproton beam.
The Aharonov–Bohm (AB) effect is one of the most striking features of quantum physics, and it is of critical importance to elucidate the role of the electromagnetic potential and its physical meaning. In spite of the fact that it was first proposed in 1949, up to now it has only been demonstrated for electrons and neutrons. We propose the realization of an experiment to study the AB effect for the antiproton, which will have the double feature of being a non-elementary charged particle and at the same time an antiparticle. The experiment will be conducted in collaboration with the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) group at the CERN AD (Antiproton Decelerator), making use of a slow antiproton beam.
The Aharonov-Bohm (AB) effect is an important discovery of quantum theory. It serves as a surprising quantum phenomenon in which an electrically charged particle can be affected by an electromagnetic potential, despite being confined to a region in which both the magnetic field and electric field are zero. This fact gives the electromagnetic potentials greater significance in quantum physics than in classical physics. The original AB effect belongs to an “electromagnetic type”. A certain vector potential is crucial for building a certain type of AB effect. In this work, we focus on the “spin”, which is an intrinsic property of microscopic particles that has been widely accepted nowadays. First, we propose the hypothesis of spin vector potential by considering a particle with a spin operator. Second, to verify the existence of such a spin vector potential, we present a gedanken double-slit interference experiment (i.e., the spin AB effect), which is possible to be observed in the lab. Third, we apply the spin vector potential to naturally explain why there were the Dzyaloshinsky-Moriya-type interaction and the dipole-dipole interaction between spins, and also predict a new type of spin-orbital interaction.
The AB (Aharonov-Bohm) effect is a pivotal quantum mechanical phenomenon that illustrates the fundamental role of the electromagnetic vector potential A in determining the phase of a charged particle's wave function, even in regions where the magnetic field B is zero.This effect demonstrates that quantum particles are influenced not only by the fields directly present but also by the potentials associated with those fields.In the AB effect, an electron beam is split into two paths, with one path encircling a solenoid and the other bypassing it.Despite the absence of a magnetic field in the regions traversed by the beams, the vector potential A associated with the magnetic flux through the solenoid induces a phase shift in the electron's wave function.This phase shift, quantified by qc , manifests as a change in the interference pattern observed in the detection screen.The phenomenon underscores the principle of gauge invariance in QED (quantum electrodynamics), where physical observables remain invariant under local gauge transformations of the vector and scalar potentials.This reinforces the notion that the vector potential A has a profound impact on quantum systems, beyond its classical role.This article outlines the AB effect, including its theoretical framework, experimental observations, and implications.The focus on the role of the vector potential in quantum mechanics provides a comprehensive understanding of this important phenomenon.
Abstract The Aharonov-Bohm (AB) effect is an important discovery in quantum theory and electrodynamics. It serves as a surprising quantum phenomenon in which an electrically charged particle can be affected by an electromagnetic potential, despite being confined to a region in which both the magnetic field and electric field are zero. This fact gives the electromagnetic potentials greater significance in quantum physics than in classical physics. Actually the original AB effect belongs to an ``electromagnetism-type". A certain type of vector potential is crucial for building the corresponding type of AB effect. In this work, we focus on the ``spin-type" AB effect. First, we derive the spin vector potential by considering a particle with a spin operator. Second, based on the spin vector potential we propose the spin AB effect, which is a gedanken double-slit interference experiment and is possible to observed in the lab. Third, we discuss the connections between the spin vector potential and some important spin interactions and predict a new type of spin-orbital interaction. Our result advances the study of the potential theory and opens a new avenue of the spin AB effect.
In 1984, 25 years after the prediction of the →Aharonov-Bohm (AB) effect, Aharonov and Casher [1] predicted a “dual ” effect. In both effects, a particle is excluded from a tubular region of space, but otherwise no force acts on it. Yet it acquires a measurable quantum phase that depends on what is inside the tube of space from which it is excluded. In the AB effect, the particle is charged and the tube contains a magnetic flux. In the Aharonov-Casher (AC) effect, the particle is neutral, but has a magnetic moment, and the tube contains a line of charge. Experiments in neutron [2], vortex [3], atom [4], and electron [5] interferometry bear out the prediction of Aharonov and Casher. Here we briefly explain the logic of the AC effect and how it is dual to the AB effect. We begin with a two-dimensional version of the AB effect. Figure 1 shows an electron moving in a plane, and also a “fluxon”, i.e. a small region of magnetic flux (pointing out of the plane) from which the electron is excluded. In Fig. 1 the fluxon is in a quantum superposition of two positions, and the electron diffracts around one of the positions but not the other. Initially, the fluxon and electron are in a
This special issue celebrates the discovery of two of the most important aspects of quantum mechanics: the Aharonov–Bohm effect and the Berry phase. The issue includes work presented at two conferences, 50 Years of the Aharonov–Bohm Effect, 11–14 October 2009, Tel Aviv University, Israel, and the Aharonov–Bohm Effect and Berry Phase 50/25 Anniversary, 14–15 December 2009, Bristol University, UK. The Aharonov–Bohm (AB) effect and the Berry phase have many things in common, apart from the happy coincidence that they were discovered 25 years apart, making possible such a joint anniversary. First, they were both discovered in the same place, the H H Wills Physics Laboratory, University of Bristol, UK. Second, they both were there for everybody to see from day one, from the very beginning of quantum mechanics. They were, so to say, right on the surface; there was no need for sophisticated mathematics or involved constructions. Yet it took so long for somebody to see them. The explanation, we dare to speculate, is that they are so unusual, they challenge so much our everyday experience and ingrained intuitions about physics that it was difficult to recognise them. Third, both the AB effect and the Berry phase are quintessentially quantum; they both manifest themselves as topological/geometric quantum phases. The AB effect revolutionized our understanding of the role of potentials in physics. For the first time, it was shown that a particle moving in a field-free region could be affected by a field in a disjoint region. In doing so, it shattered one of the strongest held principles of physics. In the case of the Berry phase, the importance lies in its absolute generality—the topological/geometric phase named after Berry is acquired by all physical systems when the external parameters they depend upon undergo an adiabatic cyclic change. Remarkably this phase depends only on the geometry of the cyclic path in the abstract parameter space, a fact which deepens our appreciation of the underlying geometry of quantum mechanics. The AB effect and the Berry phase are ubiquitous in modern physics and have implications ranging from the most fundamental to the very applied. First and foremost, they give a deeper understanding of the nature of quantum mechanics itself. Furthermore, we find them in fields as varied as cosmology, particle physics, non-abelian gauge theories, condensed matter, chemical and molecular physics, and laser dynamics. Generalizations of the AB effect to non-abelian gauge theories, such as the Wilson and `t Hooft loops, are important tools for studying confinement and spontaneous symmetry breaking. They explain charge quantization, the quantum Hall effect and the Josephson junction and also play a crucial role in electron microscope holography. Without them an understanding of many effects in the new field of mesoscopic physics, where tiny electronic circuits exhibit quantum behaviour, would be impossible. Like good wine, the AB effect and the Berry phase become finer and more appreciated with time. Even though they appear in textbooks and encyclopaedias, the number of researchers thinking and publishing papers on these two effects is increasing annually. The AB effect and the Berry phase keep being observed in new systems and with every day that passes novel applications are routinely found. This special issue is just a small snapshot of the state of the art 50 and 25 years, respectively, from their discoveries.
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.