Quantum mechanics is a fundamental theory that describes the behavior of nature at and below the scale of atoms. It is the foundation of all quantum physics, which includes quantum chemistry, quantum field theory, quantum technology, and quantum information science.
Wave-particle duality is the concept in quantum mechanics that quantum entities exhibit particle or wave properties according to the experimental circumstances. It expresses the inability of the classical concepts such as particle or wave to fully describe the behavior of quantum objects. During the 19th and early 20th centuries, light was found to behave as a wave then later discovered to have a particulate behavior, whereas electrons behaved like particles in early experiments then later discovered to have wavelike behavior. The concept of duality arose to name these seeming contradictions.
In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of measurements that have not been performed. The term "counterfactual definiteness" is used in discussions of physics calculations, especially those related to the phenomenon called quantum entanglement and those related to the Bell inequalities. In such discussions "meaningfully" means the ability to treat these unmeasured results on an equal footing with measured results in statistical calculations. It is this aspect of counterfactual definiteness that is of direct relevance to physics and mathematical models of physical systems and not philosophical concerns regarding the meaning of unmeasured results.
Atomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions, at the scale of one or a few atoms and energy scales around several electron volts. The three areas are closely interrelated. AMO theory includes classical, semi-classical and quantum treatments. Typically, the theory and applications of emission, absorption, scattering of electromagnetic radiation (light) from excited atoms and molecules, analysis of spectroscopy, generation of lasers and masers, and the optical properties of matter in general, fall into these categories.
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to electrons making a transition from a high energy state to a lower energy state. The photon energy of the emitted photons is equal to the energy difference between the two states. There are many possible electron transitions for each atom, and each transition has a specific energy difference. This collection of different transitions, leading to different radiated wavelengths, make up an emission spectrum. Each element's emission spectrum is unique. Therefore, spectroscopy can be used to identify elements in matter of unknown composition. Similarly, the emission spectra of molecules can be used in chemical analysis of substances.
Claude Cohen-Tannoudji is a French physicist. He shared the 1997 Nobel Prize in Physics with Steven Chu and William Daniel Phillips for research in methods of laser cooling and trapping atoms. Currently he is still an active researcher, working at the École normale supérieure (Paris).
The Afshar experiment is a variation of the double-slit experiment in quantum mechanics, devised and carried out by Shahriar Afshar in 2004. In the experiment, light generated by a laser passes through two closely spaced pinholes, and is refocused by a lens so that the image of each pinhole falls on a separate single-photon detector. In addition, a grid of thin wires is placed just before the lens on the dark fringes of an interference pattern.
A single-molecule magnet (SMM) is a metal-organic compound that has superparamagnetic behavior below a certain blocking temperature at the molecular scale. In this temperature range, an SMM exhibits magnetic hysteresis of purely molecular origin. In contrast to conventional bulk magnets and molecule-based magnets, collective long-range magnetic ordering of magnetic moments is not necessary.
The American Journal of Physics is a monthly, peer-reviewed scientific journal published by the American Association of Physics Teachers and the American Institute of Physics. The editor-in-chief is Beth Parks of Colgate University.
This timeline lists significant discoveries in physics and the laws of nature, including experimental discoveries, theoretical proposals that were confirmed experimentally, and theories that have significantly influenced current thinking in modern physics. Such discoveries are often a multi-step, multi-person process. Multiple discovery sometimes occurs when multiple research groups discover the same phenomenon at about the same time, and scientific priority is often disputed. The listings below include some of the most significant people and ideas by date of publication or experiment.
Anthony Philip French was a British physicist. At the time of his death he was professor emeritus of physics at the Massachusetts Institute of Technology.
Daniel Frank Walls FRS was a New Zealand theoretical physicist specialising in quantum optics.
The American Association of Physics Teachers (AAPT) was founded in 1930 for the purpose of "dissemination of knowledge of physics, particularly by way of teaching." There are more than 10,000 members in over 30 countries. AAPT publications include two peer-reviewed journals, the American Journal of Physics and The Physics Teacher. The association has two annual National Meetings and has regional sections with their own meetings and organization. The association also offers grants and awards for physics educators, including the Richtmyer Memorial Award and programs and contests for physics educators and students. It is headquartered at the American Center for Physics in College Park, Maryland.
The history of quantum mechanics is a fundamental part of the history of modern physics. The major chapters of this history begin with the emergence of quantum ideas to explain individual phenomena—blackbody radiation, the photoelectric effect, solar emission spectra—an era called the Old or Older quantum theories. Building on the technology developed in classical mechanics, the invention of wave mechanics by Erwin Schrödinger and expansion by many others triggers the "modern" era beginning around 1925. Paul Dirac's relativistic quantum theory work lead him to explore quantum theories of radiation, culminating in quantum electrodynamics, the first quantum field theory. The history of quantum mechanics continues in the history of quantum field theory. The history of quantum chemistry, theoretical basis of chemical structure, reactivity, and bonding, interlaces with the events discussed in this article.
The Planck constant, or Planck's constant, denoted by , is a fundamental physical constant of foundational importance in quantum mechanics: a photon's energy is equal to its frequency multiplied by the Planck constant, and the wavelength of a matter wave equals the Planck constant divided by the associated particle momentum. The closely related reduced Planck constant, equal to and denoted is commonly used in quantum physics equations.
Edwin Floriman Taylor is an American physicist known for his contributions to the teaching of physics. Taylor was editor of the American Journal of Physics, and is author of several introductory books to physics. In 1998 he was awarded the Oersted Medal for his contributions to the teaching of physics.
Zachary John Dutton is an American physicist who has worked on research centred mainly around cold atomic gases, EIT, low light level nonlinear optics, quantum memories, and coherent optical. Dutton graduated from Lindsay High School in Lindsay CA, and was awarded a BSc in physics from UC Berkeley in 1996. He was awarded his PhD in theoretical physics at Harvard University in 2000. His doctoral advisor was Prof.Lene Hau for his thesis entitled "Ultra-slow, stopped, and compressed light in Bose–Einstein condensates" He worked on a number of papers with Hau and Cyrus Behroozi, being amongst the first group to stop light completely. He undertook postdoctoral work at NIST–Gaithersburg with Dr. Charles Clark, prior to becoming a staff physicist at the Naval Research Lab in Washington. He conducted research centred mainly around cold atomic gases, EIT, low light level nonlinear optics, quantum memories, and coherent optical storage.
Charles H. Holbrow was an American physicist.
Quantum mechanics is a difficult subject to teach due to its counterintuitive nature. As the subject is now offered by advanced secondary schools, educators have applied scientific methodology to the process of teaching quantum mechanics, in order to identify common misconceptions and ways of improving students' understanding.
Janet Tate is a condensed-matter physicist and materials scientist whose research is centered on transparent semiconductors and their application in the design of electroluminescent devices, solar cells, and thin film electronics. Originally from South Africa, and educated in South Africa and the US, she has worked in Germany and the US, where she is University Distinguished Professor of Physics at Oregon State University.
