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In condensed matter physics, a Bose–Einstein condensate (BEC) is a state of matter that is typically formed when a gas of bosons at very low densities is cooled to temperatures very close to absolute zero. Under such conditions, a large fraction of bosons occupy the lowest quantum state, at which microscopic quantum mechanical phenomena, particularly wavefunction interference, become apparent macroscopically.
Superfluid helium-4 is the superfluid form of helium-4, an isotope of the element helium. A superfluid is a state of matter in which matter behaves like a fluid with zero viscosity. The substance, which looks like a normal liquid, flows without friction past any surface, which allows it to continue to circulate over obstructions and through pores in containers which hold it, subject only to its own inertia.
Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity.
Quantum turbulence is the name given to the turbulent flow – the chaotic motion of a fluid at high flow rates – of quantum fluids, such as superfluids. The idea that a form of turbulence might be possible in a superfluid via the quantized vortex lines was first suggested by Richard Feynman. The dynamics of quantum fluids are governed by quantum mechanics, rather than classical physics which govern classical (ordinary) fluids. Some examples of quantum fluids include superfluid helium, Bose–Einstein condensates (BECs), polariton condensates, and nuclear pasta theorized to exist inside neutron stars. Quantum fluids exist at temperatures below the critical temperature at which Bose-Einstein condensation takes place.
In condensed matter physics, a supersolid is a spatially ordered material with superfluid properties. In the case of helium-4, it has been conjectured since the 1960s that it might be possible to create a supersolid. Starting from 2017, a definitive proof for the existence of this state was provided by several experiments using atomic Bose–Einstein condensates. The general conditions required for supersolidity to emerge in a certain substance are a topic of ongoing research.
In physics, a quantum vortex represents a quantized flux circulation of some physical quantity. In most cases, quantum vortices are a type of topological defect exhibited in superfluids and superconductors. The existence of quantum vortices was first predicted by Lars Onsager in 1949 in connection with superfluid helium. Onsager reasoned that quantisation of vorticity is a direct consequence of the existence of a superfluid order parameter as a spatially continuous wavefunction. Onsager also pointed out that quantum vortices describe the circulation of superfluid and conjectured that their excitations are responsible for superfluid phase transitions. These ideas of Onsager were further developed by Richard Feynman in 1955 and in 1957 were applied to describe the magnetic phase diagram of type-II superconductors by Alexei Alexeyevich Abrikosov. In 1935 Fritz London published a very closely related work on magnetic flux quantization in superconductors. London's fluxoid can also be viewed as a quantum vortex.
Second sound is a quantum mechanical phenomenon in which heat transfer occurs by wave-like motion, rather than by the more usual mechanism of diffusion. Its presence leads to a very high thermal conductivity. It is known as "second sound" because the wave motion of entropy and temperature is similar to the propagation of pressure waves in air (sound). The phenomenon of second sound was first described by Lev Landau in 1941.
In a standard superconductor, described by a complex field fermionic condensate wave function, vortices carry quantized magnetic fields because the condensate wave function is invariant to increments of the phase by . There a winding of the phase by creates a vortex which carries one flux quantum. See quantum vortex.
Macroscopic quantum phenomena are processes showing quantum behavior at the macroscopic scale, rather than at the atomic scale where quantum effects are prevalent. The best-known examples of macroscopic quantum phenomena are superfluidity and superconductivity; other examples include the quantum Hall effect and topological order. Since 2000 there has been extensive experimental work on quantum gases, particularly Bose–Einstein condensates.
Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without any loss of kinetic energy. When stirred, a superfluid forms vortices that continue to rotate indefinitely. Superfluidity occurs in two isotopes of helium when they are liquefied by cooling to cryogenic temperatures. It is also a property of various other exotic states of matter theorized to exist in astrophysics, high-energy physics, and theories of quantum gravity. The theory of superfluidity was developed by Soviet theoretical physicists Lev Landau and Isaak Khalatnikov.
The Kibble–Zurek mechanism (KZM) describes the non-equilibrium dynamics and the formation of topological defects in a system which is driven through a continuous phase transition at finite rate. It is named after Tom W. B. Kibble, who pioneered the study of domain structure formation through cosmological phase transitions in the early universe, and Wojciech H. Zurek, who related the number of defects it creates to the critical exponents of the transition and to its rate—to how quickly the critical point is traversed.
Dieter Vollhardt is a German physicist and Professor of Theoretical Physics at the University of Augsburg.
Phase separation is the creation of two distinct phases from a single homogeneous mixture. The most common type of phase separation is between two immiscible liquids, such as oil and water. Colloids are formed by phase separation, though not all phase separations forms colloids - for example oil and water can form separated layers under gravity rather than remaining as microscopic droplets in suspension.
Clifford Michael Surko is an American physicist, whose works involve plasma physics, atomic physics, nonlinear dynamics and solid state physics. Together with his colleagues, he developed techniques for laser scattering at small angles to study waves and turbulence in tokamak plasmas and invented a positron trap that was used in experiments worldwide to study antimatter. Surko also developed other techniques for studying positron plasmas and examined atomic and plasma physics with positrons.
An electron-on-helium qubit is a quantum bit for which the orthonormal basis states |0⟩ and |1⟩ are defined by quantized motional states or alternatively the spin states of an electron trapped above the surface of liquid helium. The electron-on-helium qubit was proposed as the basic element for building quantum computers with electrons on helium by Platzman and Dykman in 1999.
William P. Halperin is a Canadian-American physicist, academic, and researcher. He is the Orrington Lunt Professor of Physics at Northwestern University.
GrigoryEfimovich Volovik is a Russian theoretical physicist, who specializes in condensed matter physics. He is known for the Volovik effect.
Frederick Reif was an American physicist. He was an emeritus professor in physics and psychology at Carnegie Mellon University.
Robert Everett Ecke is an American experimental physicist who is a laboratory fellow and director emeritus of the Center for Nonlinear Studies (CNLS) at Los Alamos National Laboratory and Affiliate Professor of Physics at the University of Washington. His research has included chaotic nonlinear dynamics, pattern formation, rotating Rayleigh-Bénard convection, two-dimensional turbulence, granular materials, and stratified flows. He is a Fellow of the American Physical Society (APS) and of the American Association for the Advancement of Science (AAAS), was chair of the APS Topical Group on Statistical and Nonlinear Physics, served in numerous roles in the APS Division of Fluid Dynamics, and was the Secretary of the Physics Section of the AAAS.
Quantum turbulence involves the chaotic dynamics of many interacting quantum vortices. In highly excited bulk superfluid, many vortex lines interact with each other forming quantum turbulent states. By introducing tight confinement along one direction the Kelvin wave excitations can be strongly suppressed, favouring vortex alignment with the axis of tight confinement. Vortex dynamics enters a regime of effective 2D motion, equivalent to point vortices moving on a plane. In general, 2D quantum turbulence (2DQT) can exhibit complex phenomenology involving coupled vortices and sound in compressible superfluids. The quantum vortex dynamics can exhibit signatures of turbulence including a Kolmogorov −5/3 power law, a quantum manifestation of the inertial transport of energy to large scales observed in classical fluids, known as an inverse energy cascade.
References
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- ↑ "California Birth Index, 1905-1995" . www.ancestry.com. 1936. Retrieved 2022-06-28.
- ↑ "U.S., Evangelical Lutheran Church in America Church Records, 1781-1969" . www.ancestry.com. Retrieved 2022-06-28.
- ↑ "George W. Rayfield". physics.uoregon.edu. Retrieved 2022-06-28.
- 1 2 Matthews, Brian (March 20, 2016). "Historical summary of the U. of O. Department of Physics: Biophysics" (PDF). uoregon.edu. Retrieved June 27, 2022.
- ↑ Rayfield, George William (1964). Quantized Vortex Rings in Superfluid Helium. University of California.
- ↑ "Notes on the History of the Department of Physics 1878-1971 | Department of Physics". physics.uoregon.edu. Retrieved 2022-06-28.
- ↑ "George Rayfield | College of Arts and Sciences". cas.uoregon.edu. Retrieved 2022-06-28.
- ↑ "Nes & Views, Faculty and Staff Newsletter" (PDF). scholarsbank.uoregon.edu. January 8, 1999. Retrieved June 28, 2022.
- ↑ "APS Fellowship". www.aps.org. Retrieved 2017-04-20.
- 1 2 "APS Fellow Archive". www.aps.org. Retrieved 2017-04-20.
- ↑ "APS Fellows 1995". www.aps.org. 1995. Retrieved 2017-04-20.