Physics of Quantum Rings

Excerpts from the recension on the 1 st edition: The book published by Vladimir M. Fomin from Leibniz Institute for Solid State and Materials Research Dresden is an authoritative monograph that offers for readers a broad, exhaustive overview about the current status of the Physics of Quantum Rings. All chapters are accessible for readers with knowledge of physics and engineering sciences within the advanced level studies. The book explores in depth the physics of quantum interference phenomena like the Aharonov-Bohm effect, which are essential for Quantum Rings. A good third of the book is dedicated to fabrication, characterization, and physical properties of such structures. The fabrication includes such methods as self-organized arrangement and crystal growth with molecular-beam epitaxy as well as high-resolution lithography. The second third of the book represents the theory of Quantum Rings, especially under the perspective of their materials and optical properties, the Coulomb interaction, and finally, their mathematical modeling. The last third of the book focuses on the Aharonov-Bohm effect of excitons, a very new effect, which is manifested through the optical properties of Quantum Rings. The unique benefit of collecting such different topics in one band consists in enabling a holistic understanding of Quantum Rings. This approach is necessary to ensure a further development in this field. On the one hand, this is a deepening exploration. On the other hand, it is equally important for implementation of the gained understanding in applications for future devices. Translated from German: K. Karrai, Physik Journal 15, 52-53 (2016). Excerpts from the recension on the 2 nd edition: A. Lorke, Physik Journal 18, 91 (2019). The editor Vladimir Fomin and contributors show impressively in their book, which has now been published in a second edition, that the now traditional classification into 3-, 2-, 1- or 0-dimensional systems is not as comprehensive as it seems. This is because, in contrast to the above-mentioned systems, Quantum Rings in mathematical sense are not singly-connected. And already the question, whether a Quantum Ring is a closed quantum wire or a quantum dot, from which the interior is cut out, demonstrates how diverse and novel is the physics offered by Quantum Rings. Also in the new edition, the numerous authors illuminate the topic from different perspectives: from materials science aspects of the growth of Quantum Rings through their optical and electronic characterization to theoretical studies of exotic topologies, such as Möbius stripes. The new division into four Sections (topology-driven effects, fabrication and characterization, optical Aharonov-Bohm Effect, theory) succeeded. It is gratifying that the newly added chapters deal with current developments and concern such topics as THz spectroscopy or 2D materials. The book is certainly not an easy reading. However, for both advanced students and scientists who wish to delve in larger breadth and depth into the topic, this collection of reviews offers an extensive material showing that also beyond a point, a line, and a plane there is still “plenty of room in the bottom”. Translated from German: : A. Lorke, Physik Journal 18, 91 (2019).
The book represents quantum rings as special class of modern high-tech materials structures at the nanoscale. It deals, in particular, with their formation by molecular beam epitaxy and droplet epitaxy of semiconductors, their topology-driven electronic, optical and magnetic properties. Highly complex theoretical models are developed to adequately explain the specific features of quantum rings. The results presented in the book serve to develop low-cost high-performance electronic, spintronic, magnetic, optoelectronic and information processing devices based on various doubly-connected structures. The third edition contains new chapters and significantly updated and extended chapters from the second edition. It provides an ample presentation of the recent advancements in the physics of quantum rings related to spin dynamics and the spin-orbit interaction (spin interference in Rashba rings, tunable exciton topology on type II InAs/GaAsSb quantum nanostructures), the electron-phonon interaction in ring-like structures, quantum-interference manifestations in novel materials (e.g., graphene cylinders, cyclocarbons, MoS 2 ), effects of electric field and THz radiation on optical properties of quantum rings and quantum-ring molecules. Special emphasis is made on fascinating novel effects emerging due to double-connectedness in various physical systems, ranging from the occurrence of the continuous geometric phase provoking formation of non-integer mode numbers in Möbius microring light cavities—through the inverse Faraday effect on the generation of current states in an array of superconductor nanorings—to the emergence of lightning-like magnetic flux bursts into a macroscopic superconductor ring. The new edition gives insight into the properties of various novel architectures, including coupled semiconductor quantum ring-quantum dot chains and concentric quantum rings, In(AsSbP) graded-composition quantum rings, topologic states of light in self-assembled and direct-printed ring-like cavities, optical and plasmon modes in Möbius-band-shaped resonators, the ferromagnetic resonance in various magnetic elements ranging from arrays of magnetic nanorings to individual 3D nanovolcanoes. It includes novel theoretical solutions to long-standing problems in the physics of quantum rings: interpretation of the observed magnetoresistance oscillations by a transmission model for superconductor quantum rings and adaptation of the Bardeen-Cooper-Schrieffer theory of superconductivity for metallic quantum rings with due account for the effects of double-connectedness on the electron properties.