A Rydberg atom is an excited atom with one or more electrons that have a very high principal quantum number, n. The higher the value of n, the farther the electron is from the nucleus, on average. Rydberg atoms have a number of peculiar properties including an exaggerated response to electric and magnetic fields, long decay periods and electron wavefunctions that approximate, under some conditions, classical orbits of electrons about the nuclei. The core electrons shield the outer electron from the electric field of the nucleus such that, from a distance, the electric potential looks identical to that experienced by the electron in a hydrogen atom.
An optical microcavity or microresonator is a structure formed by reflecting faces on the two sides of a spacer layer or optical medium, or by wrapping a waveguide in a circular fashion to form a ring. The former type is a standing wave cavity, and the latter is a traveling wave cavity. The name microcavity stems from the fact that it is often only a few micrometers thick, the spacer layer sometimes even in the nanometer range. As with common lasers, this forms an optical cavity or optical resonator, allowing a standing wave to form inside the spacer layer or a traveling wave that goes around in the ring.
Quantum networks form an important element of quantum computing and quantum communication systems. Quantum networks facilitate the transmission of information in the form of quantum bits, also called qubits, between physically separated quantum processors. A quantum processor is a machine able to perform quantum circuits on a certain number of qubits. Quantum networks work in a similar way to classical networks. The main difference is that quantum networking, like quantum computing, is better at solving certain problems, such as modeling quantum systems.
Coherent control is a quantum mechanics-based method for controlling dynamic processes by light. The basic principle is to control quantum interference phenomena, typically by shaping the phase of laser pulses. The basic ideas have proliferated, finding vast application in spectroscopy, mass spectra, quantum information processing, laser cooling, ultracold physics and more.
A spin ice is a magnetic substance that does not have a single minimal-energy state. It has magnetic moments (i.e. "spin") as elementary degrees of freedom which are subject to frustrated interactions. By their nature, these interactions prevent the moments from exhibiting a periodic pattern in their orientation down to a temperature much below the energy scale set by the said interactions. Spin ices show low-temperature properties, residual entropy in particular, closely related to those of common crystalline water ice. The most prominent compounds with such properties are dysprosium titanate (Dy2Ti2O7) and holmium titanate (Ho2Ti2O7). The orientation of the magnetic moments in spin ice resembles the positional organization of hydrogen atoms (more accurately, ionized hydrogen, or protons) in conventional water ice (see figure 1).
In quantum optics, a NOON state or N00N state is a quantum-mechanical many-body entangled state:
Atomtronics Atomtronics is the emerging quantum technology of matter-wave circuits which coherently guide propagating ultra-cold atoms. The systems typically include components analogous to those found in electronic, quantum electronics or optical systems, such as beam splitter, transistors, atomic counterpart of Superconducting Quantum Interference Devices (SQUIDs). Applications range from studies of fundamental physics to the development of practical devices.
A spaser or plasmonic laser is a type of laser which aims to confine light at a subwavelength scale far below Rayleigh's diffraction limit of light, by storing some of the light energy in electron oscillations called surface plasmon polaritons. The phenomenon was first described by David J. Bergman and Mark Stockman in 2003. The word spaser is an acronym for "surface plasmon amplification by stimulated emission of radiation". The first such devices were announced in 2009 by three groups: a 44-nanometer-diameter nanoparticle with a gold core surrounded by a dyed silica gain medium created by researchers from Purdue, Norfolk State and Cornell universities, a nanowire on a silver screen by a Berkeley group, and a semiconductor layer of 90 nm surrounded by silver pumped electrically by groups at the Eindhoven University of Technology and at Arizona State University. While the Purdue-Norfolk State-Cornell team demonstrated the confined plasmonic mode, the Berkeley team and the Eindhoven-Arizona State team demonstrated lasing in the so-called plasmonic gap mode. In 2018, a team from Northwestern University demonstrated a tunable nanolaser that can preserve its high mode quality by exploiting hybrid quadrupole plasmons as an optical feedback mechanism.
Klaus Blaum is a German physicist and director at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany.
An optical transistor, also known as an optical switch or a light valve, is a device that switches or amplifies optical signals. Light occurring on an optical transistor's input changes the intensity of light emitted from the transistor's output while output power is supplied by an additional optical source. Since the input signal intensity may be weaker than that of the source, an optical transistor amplifies the optical signal. The device is the optical analog of the electronic transistor that forms the basis of modern electronic devices. Optical transistors provide a means to control light using only light and has applications in optical computing and fiber-optic communication networks. Such technology has the potential to exceed the speed of electronics, while conserving more power. The fastest demonstrated all-optical switching signal is 900 attoseconds, which paves the way to develop ultrafast optical transistors.
A single-photon source is a light source that emits light as single particles or photons. Single-photon sources are distinct from coherent light sources (lasers) and thermal light sources such as incandescent light bulbs. The Heisenberg uncertainty principle dictates that a state with an exact number of photons of a single frequency cannot be created. However, Fock states can be studied for a system where the electric field amplitude is distributed over a narrow bandwidth. In this context, a single-photon source gives rise to an effectively one-photon number state.
Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface. Originally discovered for sound waves in the whispering gallery of St Paul's Cathedral, they can exist for light and for other waves, with important applications in nondestructive testing, lasing, cooling and sensing, as well as in astronomy.
Immanuel Bloch is a German experimental physicist. His research is focused on the investigation of quantum many-body systems using ultracold atomic and molecular quantum gases. Bloch is known for his work on atoms in artificial crystals of light, optical lattices, especially the first realization of a quantum phase transition from a weakly interacting superfluid to a strongly interacting Mott insulating state of matter.
Tilman Esslinger is a German experimental physicist. He is Professor at ETH Zurich, Switzerland, and works in the field of ultracold quantum gases and optical lattices.
Christopher Roy Monroe is an American physicist and engineer in the areas of atomic, molecular, and optical physics and quantum information science, especially quantum computing. He directs one of the leading research and development efforts in ion trap quantum computing. Monroe is the Gilhuly Family Presidential Distinguished Professor of Electrical and Computer Engineering and Physics at Duke University and is College Park Professor of Physics at the University of Maryland and Fellow of the Joint Quantum Institute and Joint Center for Quantum Computer Science. He is also co-founder of IonQ, Inc.
Jürgen Mlynek is a German physicist and was president of the Helmholtz Association of German Research Centres from 2005 to 2015.
Cavity optomechanics is a branch of physics which focuses on the interaction between light and mechanical objects on low-energy scales. It is a cross field of optics, quantum optics, solid-state physics and materials science. The motivation for research on cavity optomechanics comes from fundamental effects of quantum theory and gravity, as well as technological applications.
Michel Devoret is a French physicist and F. W. Beinecke Professor of Applied Physics at Yale University. He also holds a position as the Director of the Applied Physics Nanofabrication Lab at Yale. He is known for his pioneering work on macroscopic quantum tunneling, and the single-electron pump as well as in groundbreaking contributions to initiating the fields of circuit quantum electrodynamics and quantronics.
Bose–Einstein condensation of polaritons is a growing field in semiconductor optics research, which exhibits spontaneous coherence similar to a laser, but through a different mechanism. A continuous transition from polariton condensation to lasing can be made similar to that of the crossover from a Bose–Einstein condensate to a BCS state in the context of Fermi gases. Polariton condensation is sometimes called “lasing without inversion”.
Christine A. Muschik is an assistant professor in the Department of Physics and Astronomy at the University of Waterloo as well as a part of the Institute for Quantum Computing. She completed her PhD in 2011 at the Max-Planck-Institute for Quantum Optics. She completed postdoctoral fellowships at the Institute for Quantum Optics and Quantum Information in Innsbruck and the Institute of Photonic Sciences in Castelldefels. As of 2020, she has over 2000 citations on over 50 publications. She has also been featured in several articles in Nature magazine, MIT Technology Review, and Physics World.
