In physics, dephasing is a mechanism that recovers classical behaviour from a quantum system. It refers to the ways in which coherence caused by perturbation decays over time, and the system returns to the state before perturbation. It is an important effect in molecular and atomic spectroscopy, and in the condensed matter physics of mesoscopic devices.
Stochastic electrodynamics (SED) is a variant of classical electrodynamics (CED) of theoretical physics. SED consists of a set of controversial theories that posit the existence of a classical Lorentz invariant radiation field having statistical properties similar to that of the electromagnetic zero-point field (ZPF) of quantum electrodynamics (QED).
Quantum metrology is the study of making high-resolution and highly sensitive measurements of physical parameters using quantum theory to describe the physical systems, particularly exploiting quantum entanglement and quantum squeezing. This field promises to develop measurement techniques that give better precision than the same measurement performed in a classical framework. Together with quantum hypothesis testing, it represents an important theoretical model at the basis of quantum sensing.
Édouard Brézin is a French theoretical physicist. He is professor at Université Paris 6, working at the laboratory for theoretical physics (LPT) of the École Normale Supérieure since 1986.
A quantum point contact (QPC) is a narrow constriction between two wide electrically conducting regions, of a width comparable to the electronic wavelength.
Sound amplification by stimulated emission of radiation (SASER) refers to a device that emits acoustic radiation. It focuses sound waves in a way that they can serve as accurate and high-speed carriers of information in many kinds of applications—similar to uses of laser light.
Marvin Lou Cohen is an American–Canadian theoretical physicist. He is a physics professor at the University of California, Berkeley. Cohen is a leading expert in the field of condensed matter physics. He is widely known for his seminal work on the electronic structure of solids.
Volker Heine FRS is a New Zealand / British physicist. He is married to Daphne and they have three children. Volker Heine is considered a pioneer of theoretical and computational studies of the electronic structure of solids and liquids and the determination of physical properties derived from it.
Atomtronics is an emerging type of computing consisting of matter-wave circuits which coherently guide propagating ultra-cold atoms. The systems typically include components analogous to those found in electronic or optical systems, such as beam splitters and transistors. Applications range from studies of fundamental physics to the development of practical devices.
Xiao-Gang Wen is a Chinese-American physicist. He is a Cecil and Ida Green Professor of Physics at the Massachusetts Institute of Technology and Distinguished Visiting Research Chair at the Perimeter Institute for Theoretical Physics. His expertise is in condensed matter theory in strongly correlated electronic systems. In Oct. 2016, he was awarded the Oliver E. Buckley Condensed Matter Prize.
Alex Zunger is a theoretical physicist, research professor, at the University of Colorado Boulder. He has authored more than 150 papers in Physical Review Letters and Physical Reviews B Rapid Communication, has an h-index over 150, number of citations over 113,000. He co-authored one of the top-five most cited papers ever to be published in the Physical Review family in its over 100 years' history.
In astronomy, optics and particle physics, the Bose–Einstein correlations refer to correlations between identical bosons.
Peter Hänggi is a theoretical physicist from Switzerland, Professor of Theoretical Physics at the University of Augsburg. He is best known for his original works on Brownian motion and the Brownian motor concept, stochastic resonance and dissipative systems. Other topics include, driven quantum tunneling, such as the discovery of coherent destruction of tunneling (CDT), phononics, relativistic statistical mechanics and the foundations of classical and quantum thermodynamics.
Peter Heszler was a Hungarian physicist. He is well known for, among others, his research on laser-assisted nanoparticle synthesis. His research included nanotechnology, condensed matter physics, materials science, fluctuations and noise, laser science and chemical sensors, including fluctuation-enhanced sensing.
The SP formula for the dephasing rate of a particle that moves in a fluctuating environment unifies various results that have been obtained, notably in condensed matter physics, with regard to the motion of electrons in a metal. The general case requires to take into account not only the temporal correlations but also the spatial correlations of the environmental fluctuations. These can be characterized by the spectral form factor , while the motion of the particle is characterized by its power spectrum . Consequently, at finite temperature the expression for the dephasing rate takes the following form that involves S and P functions:
Within quantum cryptography, the Decoy state quantum key distribution (QKD) protocol is the most widely implemented QKD scheme. Practical QKD systems use multi-photon sources, in contrast to the standard BB84 protocol, making them susceptible to photon number splitting (PNS) attacks. This would significantly limit the secure transmission rate or the maximum channel length in practical QKD systems. In decoy state technique, this fundamental weakness of practical QKD systems is addressed by using multiple intensity levels at the transmitter's source, i.e. qubits are transmitted by Alice using randomly chosen intensity levels, resulting in varying photon number statistics throughout the channel. At the end of the transmission Alice announces publicly which intensity level has been used for the transmission of each qubit. A successful PNS attack requires maintaining the bit error rate (BER) at the receiver's end, which can not be accomplished with multiple photon number statistics. By monitoring BERs associated with each intensity level, the two legitimate parties will be able to detect a PNS attack, with highly increased secure transmission rates or maximum channel lengths, making QKD systems suitable for practical applications.
James Power Gordon was an American physicist known for his work in the fields of optics and quantum electronics. His contributions include the design, analysis and construction of the first maser in 1954 as a doctoral student at Columbia University under the supervision of C. H. Townes, development of the quantal equivalent of Shannon's information capacity formula in 1962, development of the theory for the diffusion of atoms in an optical trap in 1980, and the discovery of what is now known as the Gordon-Haus effect in soliton transmission, together with H. A. Haus in 1986. Gordon was a member of the National Academy of Engineering and the National Academy of Sciences.
Stephan W. Koch was a German theoretical physicist. He was a professor at the University of Marburg and works on condensed-matter theory, many-body effects, and laser theory. He is best known for his seminal contributions to the optical and electronic properties of semiconductors, semiconductor quantum optics, and semiconductor laser designs. Major portion of his research work has focused on the quantum physics and application potential of semiconductor nanostructures. Besides gaining fundamental insights to the many-body quantum theory, his work has provided new possibilities to develop, e.g., laser technology, based on accurate computer simulations. His objective has been to self-consistently include all relevant many-body effects in order to eliminate phenomenological approximations that compromise predictability of effects and quantum-device designs.
Quantum Hall transitions are the quantum phase transitions that occur between different robustly quantized electronic phases of the quantum Hall effect. The robust quantization of these electronic phases is due to strong localization of electrons in their disordered, two-dimensional potential. But, at the quantum Hall transition, the electron gas delocalizes as can be observed in the laboratory. This phenomenon is understood in the language of topological field theory. Here, a vacuum angle distinguishes between topologically different sectors in the vacuum. These topological sectors correspond to the robustly quantized phases. The quantum Hall transitions can then be understood by looking at the topological excitations (instantons) that occur between those phases.
Malvin Carl Teich is an American physicist and computational neuroscientist and Professor Emeritus at Columbia University and Boston University. He is also a consultant to government, academia, and private industry, where he serves as an advisor in intellectual-property conflicts. He is the coauthor of Fundamentals of Photonics, and of Fractal-Based Point Processes.
