Quanten, Atome, Kerne, Teilchen

Classical and Quantum Optics is the first text to cover classical and quantum optics as a single subject with the premise that genuine understanding of light requires mastery of both fields. It addresses all aspects of light equally, including geometric optics, wave optics, electromagnetic optics, and quantum optics. This timely book supplies the tools needed to fully explore the behavior of light. Classical and Quantum Optics:Approaches the topic from a conceptual perspective without assuming the reader's knowledgeIncludes relatively little math, making it ideal for students in applied sciences and engineeringStarts with well-established hypotheses and builds on them to explain physical effects and experimental observations Classical and Quantum Optics is suitable for emerging researchers and professionals in optics, natural sciences, engineering, and interdisciplinary fields, as well as students in physics, applied sciences, and engineering.

The whole theoretical framework of physics rests only on a few but profound principles. Wigner enlightened us by elucidating that “It is now natural for us to try to derive the laws of nature and to test their validity by means of the laws of invariance, rather than to derive the laws of invariance from what we believe to be the laws of nature.” Issues pertaining to symmetry, invariance principles and fundamental laws challenge the most gifted minds today. These topics require a deep and extensive understanding of both ‘quantum mechanics’ and the ‘theory of relativity’. We attempt in this pedagogical article to present a heuristic understanding of these fascinating relationships based only on rather elementary considerations in classical and quantum mechanics. An introduction to some fundamental considerations regarding continuous symmetries, dynamical symmetries (Part 1), and discrete symmetries (Part 2) (parity, charge conjugation and time-reversal), and their applications in atomic, nuclear and particle physics, will be presented.

The development of powerful laser cooling and trapping techniques has made possible the controlled realization of dense and cold gaseous samples, thus opening the way for investigations in the ultracold temperature regimes not accessible with conventional techniques. A Bose-Einstein condensate (BEC) represents a peculiar gaseous state where all the particles reside in the same quantum mechanical state. Therefore BECs exhibit quantum mechanical phe-nomena on a macroscopic scale with a single quantum mechanical wavefunction describing the external degrees of freedom. That control of the external degrees of freedom is combined with a precise control of the internal degrees. The BEC investigation has become a very active area of research in contem-porary physics. The BEC study encompasses different subfields of physics, i.e., atomic and molecular physics, quantum optics, laser spectroscopy, solid state physics. Atomic physics and laser spectroscopy provide the methods for creating and manipulating the atomic and molecular BECs. However owing to the interactions between the particles composing the condensate and to the configuration of the external potential, concepts and methods from solid state physics are extensively used for BEC description.KeywordsWave PacketBrillouin ZoneOptical LatticePeriodic PotentialTunneling ProbabilityThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

The year 2015 was the International Year of Light. However, it also marked, the 20th anniversary of the first observation of Bose–Einstein condensation in atomic vapors by Eric Cornell, Carl Wieman and Wolfgang Ketterle. This discovery could be considered as one of the greatest achievements of quantum optics that has triggered an avalanche of further seminal discoveries and achievements. For this reason we devote this essay for the focus issue on ‘Quantum Optics in the International Year of Light’ to the recent revolutionary developments in quantum optics at the frontiers of all physics: atomic physics, molecular physics, condensed matter physics, high energy physics and quantum information science. We follow here the lines of the introduction to our book ‘Ultracold atoms in optical lattices: Simulating quantum many-body systems’ (Lewenstein et al 2012 Ultracold Atoms in Optical Lattices: Simulating Quantum Many-body Systems (Oxford: University Press)), and to a lesser extent the review article M Lewenstein et al (2007 Adv. Phys. 56 243). The book, however, was published in 2012, and many things has happened since then—the present essay is therefore upgraded to include the latest developments.

Vacuum is what remains when there is nothing left in space. But this "nothing" is still able to act on objects placed in vacuum. The archetype of such an action of vacuum is the so-called Casimir force.In fact vacuum consists in fluctuating electromagnetic fields propagating through space with the speed of light, and having the minimal fluctuation energy allowed by quantum theory. Since vacuum energy is a minimum, it cannot be used to extract work. But the fluctuations have observable consequences in atomic and subatomic physics. An atom interacting only with vacuum fields suffers spontaneous emission processes which can be considered as induced by these fields. When fallen in its ground state, the atom no longer emits photons but its coupling to vacuum results in a measurable Lamb shift of the absorption frequencies.Two atoms located at different places experience an attractive van der Waals force which plays an important role in physico-chemical and biological processes. Casimir was studying this effect when he discovered in 1948 that two mirrors placed in vacuum are attracted towards each other.There are many reasons for the growing interest in this Casimir force. Progress in experimental techniques have recently allowed for accurate measurements and have then led to tests of this crucial prediction of quantum electrodynamics. These tests have required theoretical developments for dealing satisfactory with the description of the optical response of mirrors or of geometry of the experiments. They have also made it possible to extend the search for hypothetical new weak forces into the distance range where the Casimir force dominates over other forces.Nevertheless, in spite of all this progress and renewal interest on the subject there are still basic questions that have not been answered and extensions that have not been achieved, for example a consistent treatment of temperature effects or a full theory of geometrical effects between mirrors made of real materials.Recently it has been recognized that vacuum induced forces played a considerable role in micro- and nano-electromechanical systems (MEMS or NEMS) with typical sizes in the µm range or below. The emerging interface between quantum Casimir forces and nanophysics is already clearly visible in this Focus Issue, and it will certainly gain more and more importance in the forthcoming years.The topics covered by the articles in this Focus Issue of New Journal of Physics reflect the increasing activity and broadening spectrum of the studies connected to the Casimir forces. We hope that the reader will find in this collection of papers new research results or proposals as well as reviews by experts of a large set of open issues which are currently addressed by an expanding community. We also hope that the issue will interest the non-expert readers and draw their attention to this exciting and interdisciplinary research field.The articles below represent the first contributions and further additions will appear.Focus on Casimir Forces ContentsCasimir energy with a Robin boundary: the multiple-reflection cylinder-kernel expansion Z Liu and S A Fulling On the use of hydrogen switchable mirrors in Casimir force experiments Sven de Man and Davide Iannuzzi Thermal corrections to the Casimir effect Iver Brevik, Simen Ellingsen and K Milton Casimir forces and non-Newtonian gravitation R Onofrio Sample dependence of the Casimir force I Pirozhenko, A Lambrecht and V B Svetovoy Casimir effect: a novel experimental approach at large separation P Antonini, G Bressi, G Carugno, Giuseppe Galeazzi, Giuseppe Messineo and G Ruoso Exact zero-point interaction energy between cylinders F D Mazzitelli, D A R Dalvit and F C Lombardo Stability and the proximity theorem in Casimir actuated nano devices R Esquivel-Sirvent, Luis Reyes and Jeffrey Bárcenas Casimir effect for arbitrary materials: contributions within and beyond the light cone W L Mochán and C Villarreal The Casimir effect within scattering theory A Lambrecht, Neto P A Maia and S Reynaud Quantum electrodynamical torques in the presence of Brownian motion Jeremy N Munday, Davide Iannuzzi and F Capasso Rubén G Barrera, Universidad Nacional Autónoma de México, Mexico Serge Reynaud, Université Pierre et Marie Curie, Paris, France

Physics Today’s September 1966 issue included an interview with Herman Branson, who was chair of Howard University’s physics department at the time. Among the questions he fielded about the state of Black people in physics was, “Do you feel that the science community is biased to any degree?” He replied, “I don’t think so…. Scientists (and especially physicists) are among the most liberal people to be found anywhere.”Branson’s response evidently shocked his fellow African American physicist Tannie Stovall of the Linear Accelerator Laboratory in Orsay, France. He submitted a rebuttal, which appeared in Physics Today’s December 1966 issue. “Branson has painted a dangerously rosy picture of the black man in physics,” Stovall wrote. “I would like strongly to take issue with this view.”How could Branson believe that racial bias was absent from science in 1966? I can’t be sure. He might have harbored a belief that persists today: Physics is the objective, methodical study of matter and energy, which are devoid of life, let alone social and political actors. How can physics be biased?But if you read Branson’s interview, it’s clear he was quite aware of the systemic obstacles faced half a century ago by Black students in science. Indeed, he campaigned to remove them. Black colleges and universities had—and still have—less funding than other universities. “We know how to make a first-rate school in America,” Branson told his interviewer. “It’s primarily a question of money.”When Physics Today published its interview with Branson, the last of the five Civil Rights Acts of the 1950s and 1960s—the Fair Housing Act of 1968—was stalled in the Senate. Asked if his physics students were as active in civil rights as humanities students, Branson answered, “Perhaps embarrassingly so.” Quite to his surprise, physics majors were among the student leaders in local civil rights movements. Some of them, he lamented, did not continue to pursue physics.As members of a prominent Black university in the US, those “lost” students of Branson’s who joined the struggle for civil rights were surely made welcome in the physics department. Sadly and reprehensibly, too many of today’s Black physics majors and graduate students do not feel as though they belong. If you doubt that physics is unwelcoming to Black students, read the commentary by Charles D. Brown II, which was posted on Physics Today’s website on 20 July. Brown, who is a postdoc in atomic physics at the University of California, Berkeley, recounts a litany of racist slights and presumptions that he faced as a physics student.Making physics more welcoming to Black people and other underrepresented groups will take effort, not least because a student’s peers have a strong influence on whether a department is welcoming. Professors must lead by example. If you need advice on how to do that, read the report11. AIP National Task Force to Elevate African American Representation in Undergraduate Physics & Astronomy, The Time Is Now: Systemic Changes to Increase African Americans with Bachelor’s Degrees in Physics and Astronomy, American Institute of Physics (2020). from the TEAM-UP Task Force, which was organized by the American Institute of Physics (Physics Today’s publisher).A recent briefing in the Economist identified three policy areas that, if addressed effectively, could improve the lives and opportunities of African Americans: segregation, education, and childhood poverty. Although tackling those and other systemic sources of disadvantage will be expensive and difficult, it needs to be done. And Branson recognized another challenge in his 1966 interview: “Suppose you take a 17-year-old from an indifferent intellectual and cultural background; what can you do to bring him into 20th-century science? It’s not only a tough question for America but for the rest of the world as well.”Given the magnitude of the challenges, the individual physicist, including me, might be tempted to ask with exasperation, What can I do? We can listen to the personal experiences of Black physicists. We can work toward making our departments, labs, and teams more welcoming. And we can confront racism whenever we encounter or witness it. The killing of George Floyd on 25 May again brought into stark, painful view the anti-Black racism that endures in the US. The time is now to do what we can to eliminate it.ReferenceSection:ChooseTop of pageReference <<CITING ARTICLES1. AIP National Task Force to Elevate African American Representation in Undergraduate Physics & Astronomy, The Time Is Now: Systemic Changes to Increase African Americans with Bachelor’s Degrees in Physics and Astronomy, American Institute of Physics (2020). Google Scholar© 2020 American Institute of Physics.

Physics students at Worcester State University visit the Worcester Art Museum (WAM) at the end of a special 100-level course called Physics in Art. The students have studied geometrical optics, and they have been introduced to concepts in atomic physics. The purpose of the museum tour is to show how physics-based techniques can be used in a nontraditional lab setting. Other examples of the use of museum-based art in physics instruction include analyses of Pointillism and image resolution, and of reflections in soap bubbles in 17- and 18th-century paintings.

Gerhard L Weissler, Distinguished Professor Emeritus of Physics at the University of Southern California, and founder of this series of International Conferences on Vacuum Ultraviolet Radiation Physics, died of cancer on Sunday 13 June 1989, at his home in Encino, California at the age of 71.Professor Weissler was born in northern Germany in 1918 and, after having earned his BS degree in physics from theInstitute of Technology, Berlin in 1938, he came to the United States as a graduate student in physics at UC Berkeley. He earned his MS and PhD degrees in physics from UC Berkeley in 1941 and 1942, respectively. From 1942 to 1944 Professor Weissler was an instructor of medical physics at the University of California Medical School. In 1944. Professor Weissler joined the Department of Physics of the University of Southern California as an AssistantProfessor, where he was promoted to full professor in 1952. In addition to directing his primary research program in atomic and molecular physics, he also served as the Department Chairman from 1951 to 1956. and directed USC's NuclearAccelerator Laboratory from 1955 to 1965. He retired in 1988.In 1979, USC honored him with an Associates Award for Excellence in Teaching and in March 1989 he received USC'sSpecial Emeritus Award. Professor Weissler was also a fellow of both the American Physical Society and the Optical Society of America.His illustrious career was devoted to the pursuit of excellence, and he succeeded admirably. He was one of the preeminent pioneers in the field of vacuum ultraviolet spectroscopy, carrying out research in all phases of vacuum ultraviolet physics. He invented the condensed spark discharge light sources which were a key to the early investigations of both the structure and absorption cross sections of atoms and molecules. He also used these light sources to study solid state and collective phenomena. The availability of his very bright light sources, together with increasingly improved vacuum systems, made much of this work possible for the first time. The early literature on the absorption spectra of atoms and molecules in the VUV region is dominated by the work of Professor Weissler and his many students. As his research evolved, specific processes involved in the absorption of very short wavelength radiation were identified. Quantifying these processes is the subject of much current research, as is evident from the variety of papers presented in the present proceedings.For almost 30 years, the large and active group of faculty members, students, and research associates assembled byProfessor Weissler made USC one of the world's centers in ultraviolet atomic and molecular spectroscopy. Many membersof this group are well known scientists who have established distinguished careers in major universities and industrial and government laboratories; one of his post-doctoral fellows is at this time President of the University of Munich, one of the leading universities in the world. The highly successful careers of his many graduate and postdoctoral students were surely given a running start by the quality of their research experience under his guidance. His enthusiasm and extraordinary energy level were highly infectious, and he will be sorely missed by all of us who knew him.Professor Weissler is survived by his wife, Claire, and two sons, Roderick and Robert.

Phase Transition Dynamics

Typical suspended one-dimensional waveguides, tapered optical fibers (TOFs), combine sub-wavelength optical confinement with mechanical flexibility, enabling applications in optomechanics, quantum optics, atomic physics and sensing. However, the intrinsic mechanical modes (IMMs) of TOF, including flexural, longitudinal, and torsional modes, remain underexplored. Through analytical formulations and simulations, we comprehensively and explicitly explore the classification of various mechanical modes of a TOF. The characteristics of various TOF IMMs are investigated in detail, including frequencies, displacements, and vibration patterns. Novel degenerate IMMs are confirmed, and these modes result from dynamic coupling between the modes in the tapered and waist regions. It is also revealed that the IMMs are strongly geometry-dependent. The frequencies scale with the length and diameter of the waist, whereas linear tapers exhibit stronger energy localization than exponential tapers. The elaborate design and engineering of TOFs allow for precise mechanical resonance tuning and seamless integration with nanophotonic systems, positioning them as a versatile platform for quantum precision metrology and advanced optomechanical technologies.

Dark state physics has led to a variety of remarkable phenomena in atomic physics, quantum optics, and information theory. Here, we investigate interacting dark resonance type physics in multi-layered plasmonic meta-molecules. We theoretically demonstrate that these plasmonic meta-molecules exhibit sub-natural spectral response, analogous to conventional atomic four-level configuration, by manipulating the evanescent coupling between the bright and dark elements (plasmonic atoms). Using cascaded coupling, we show nearly 4-fold reduction in linewidth of the hybridized resonance compared to a resonantly excited single bright plasmonic atom with same absorbance. In addition, we engineered the geometry of the meta-molecules to realize efficient intramolecular excitation transfer with nearly 80%, on resonant excitation, of the total absorption being localized at the second dark plasmonic atom. An analytical description of the spectral response of the structure is presented with full electrodynamics simulations to corroborate our results. Such multilayered meta-molecules can bring a new dimension to higher quality factor plasmonic resonance, efficient excitation transfer, wavelength demultiplexing, and enhanced non-linearity at nanoscale.

Bosonic systems, particularly in quantum optics and atomic physics, are leading platforms for achieving quantum enhanced precision in parameter estimation. By exploiting properties such as mode and particle entanglement, it is possible to attain precisions that surpass the shot noise limit with respect to key resources like probe number or energy. Yet the mechanisms by which these bosonic resources enable quantum enhancement remain unclear. Consequently, the design of optimal probes and evolutions often relies on case by case analyses, where continuous and discrete variable regimes are treated separately and their connection is still unclear. We develop a comprehensive framework for quantum metrology that unifies all known precision enhancement mechanisms based on bosonic systems. Our approach employs a superselection rule compliant representation of the electromagnetic field that explicitly includes the phase reference, thereby enforcing total particle number conservation and bridging the discrete and continuous limits of quantum optics and symmetric massive systems. Within this unified formalism, of which established results emerge as special cases, we identify the distinct roles of mode and particle entanglement for quantum enhanced precision. The framework further provides general measurement optimization strategies for arbitrary multimode entangled probe states and naturally incorporates noise and non-unitary dynamics, ensuring applicability to realistic experimental conditions.

Diode lasers are widely used in atomic physics given their narrow linewidth and wavelength tunability. Nevertheless, although they present low noise for their intensity, excessive noise in the phase limits their application in quantum optics. Looking for reduction of this phase noise, we built and characterized a ring laser, using a semiconductor-tapered amplifier as the gain medium. We were able to reduce the phase noise of a diode laser to a factor of 10 above shot-noise level, bringing it closer to a useful coherent state for applications in quantum information.

It is a straightforward result of electromagnetism that dipole oscillators radiate more strongly when they are synchronized, and that if there are $N$ dipoles, the overall emitted intensity scales with $N^2$. In atomic physics, such an enhanced radiative property appears when coherence among two-level identical atoms is established, and is well-known as "superradiance" \cite{Dicke:1954aa}. In superfluorescence (SF), atomic coherence develops via a self-organisation process stemming from the common radiated field, starting from a incoherently prepared population inversion \cite{Bonifacio:1975aa}. First demonstrated in a gas \cite{Skribanowitz:1973} and later in condensed matter systems \cite{Florian:1984}, its potential is currently being investigated in the fields of ultranarrow linewidth laser development for fundamental tests in physics \cite{Meiser:2009,Meiser:2010,Bohnet:2012aa,Norcia:2016, Norcia:2018}, and for the development of devices enabling entangled multi-photon quantum light sources \cite{Raino:2018aa,Angerer:2018aa}. A barely developed aspect in superradiance is related to the properties of the dipole array that generates the pulsed radiation field. In this work we establish the experimental conditions for formation of a macroscopic dipole via superfluorescence, involving the remarkable number of $4\times10^{12}$ atoms. Even though rapidly evolving in time, it represents a flexible test-bed in quantum optics. Self-driven atom dynamics, without the mediation of cavity QED nor quantum dots or quantum well structures, is observed in a cryogenically-cooled rare-earth doped material. We present clear evidence of a decay rate that is enhanced by more than 1-million times compared to that of independently emitting atoms. We thoroughly resolve the dynamics by directly measuring the intensity of the emitted radiation as a function of time.

The development of DOEs fabrication techniques is continuously growing due to the wide range of industrial applications, such as beam manipulation or optical position encoders. In this work, we use Femtosecond laser direct writing to manufacture DOEs, which uses a simpler and more efficient way to fabricate amplitude binary masks. Also, we have analyzed the performance of the DOEs. The fabrication technique is validated since the experimental results are in accordance to numerical simulations.