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Fractional Quantum Hall Effect
The fractional quantum Hall effect (fractional QHE or FQHE) is the observation of precisely quantized plateaus in the Hall conductance of 2-dimensional (2D) electrons at fractional values of e^2/h, where ''e'' is the electron charge and ''h'' is the Planck constant. At the same time, longitudinal resistance drops to zero (for low enough temperatures) as for the integer QHE. It is a property of a collective state in which electrons bind magnetic flux lines to make new quasiparticles, and excitations have a fractional elementary charge and possibly also fractional statistics. The 1998 Nobel Prize in Physics was awarded to Robert Laughlin, Horst Störmer, and Daniel Tsui "for their discovery of a new form of quantum fluid with fractionally charged excitations". The microscopic origin of the FQHE is a major research topic in condensed matter physics. Descriptions The fractional quantum Hall effect (FQHE) is a collective behavior in a 2D system of electrons. In particular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Hall Effect
The quantum Hall effect (or integer quantum Hall effect) is a quantized version of the Hall effect which is observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall resistance exhibits steps that take on the quantized values : R_ = \frac = \frac , where is the Hall voltage, is the channel current, is the elementary charge and is the Planck constant. The divisor can take on either integer () or fractional () values. Here, is roughly but not exactly equal to the filling factor of Landau levels. The quantum Hall effect is referred to as the integer or fractional quantum Hall effect depending on whether is an integer or fraction, respectively. The striking feature of the integer quantum Hall effect is the persistence of the quantization (i.e. the Hall plateau) as the electron density is varied. Since the electron density remains constant when the Fermi level is in a clean spectral gap, this situation corre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert B
The name Robert is an ancient Germanic given name, from Proto-Germanic "fame" and "bright" (''Hrōþiberhtaz''). Compare Old Dutch ''Robrecht'' and Old High German ''Hrodebert'' (a compound of ''Hrōþ, Hruod'' () "fame, glory, honour, praise, renown, godlike" and ''berht'' "bright, light, shining"). It is the second most frequently used given name of ancient Germanic origin.Reaney & Wilson, 1997. ''Dictionary of English Surnames''. Oxford University Press. It is also in use Robert (surname), as a surname. Another commonly used form of the name is Rupert (name), Rupert. After becoming widely used in Continental Europe, the name entered England in its Old French form ''Robert'', where an Old English cognate form (''Hrēodbēorht'', ''Hrodberht'', ''Hrēodbēorð'', ''Hrœdbœrð'', ''Hrœdberð'', ''Hrōðberχtŕ'') had existed before the Norman Conquest. The feminine version is Roberta (given name), Roberta. The Italian, Portuguese, and Spanish form is Roberto (given name), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Gossard
Arthur C. Gossard (June 18, 1935 – June 26, 2022) was a professor of materials and electrical engineering at the University of California, Santa Barbara. In 1982, he co-discovered the fractional quantum Hall effect. His research is related to molecular beam epitaxy (MBE). He has a doctorate in physics from UC Berkeley. After university, he joined Bell Labs. In 1987, he was elected a member of the US National Academy of Engineering for contributions to the study of the physics of ultra-thin semiconducting layers through molecular beam epitaxy, leading to new physics and new devices. He was also a member of the US National Academy of Sciences. In 2016, Gossard was named as a recipient of a National Medal of Technology and Innovation The National Medal of Technology and Innovation (formerly the National Medal of Technology) is an honor granted by the president of the United States to American inventors and innovators who have made significant contributions to the development .. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gallium Arsenide
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and optical windows. GaAs is often used as a substrate material for the epitaxial growth of other III-V semiconductors, including indium gallium arsenide, aluminum gallium arsenide and others. History Gallium arsenide was first synthesized and studied by Victor Goldschmidt in 1926 by passing arsenic vapors mixed with hydrogen over gallium(III) oxide at 600 °C. The semiconductor properties of GaAs and other Compound semiconductor, III-V compounds were patented by Heinrich Welker at Siemens-Schuckert in 1951 and described in a 1952 publication. Commercial production of its monocrystals commenced in 1954, and more studies followed in the 195 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterostructure
A heterojunction is an interface between two layers or regions of dissimilar semiconductors. These semiconducting materials have unequal band gaps as opposed to a homojunction. It is often advantageous to engineer the electronic energy bands in many solid-state device applications, including semiconductor lasers, solar cells and transistors. The combination of multiple heterojunctions together in a device is called a heterostructure, although the two terms are commonly used interchangeably. The requirement that each material be a semiconductor with unequal band gaps is somewhat loose, especially on small length scales, where electronic properties depend on spatial properties. A more modern definition of heterojunction is the interface between any two solid-state materials, including crystalline and amorphous structures of metallic, insulating, fast ion conductor and semiconducting materials. Manufacture and applications Heterojunction manufacturing generally requires the use o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horst Ludwig Störmer
Horst Ludwig Störmer (; born April 6, 1949) is a German physicist, Nobel laureate and emeritus professor at Columbia University. He was awarded the 1998 Nobel Prize in Physics jointly with Daniel Tsui and Robert Laughlin "for their discovery of a new form of quantum fluid with fractionally charged excitations" (the fractional quantum Hall effect). He and Tsui were working at Bell Labs at the time of the experiment cited by the Nobel committee. Biography Störmer was born in Frankfurt am Main, and grew up in the nearby town of Sprendlingen. After graduating from the Goetheschule in Neu-Isenburg in 1967, he enrolled in architectural engineering at the TH Darmstadt, but later moved to the Goethe University Frankfurt to study physics, but since he had missed the registration period for physics, he began with a mathematics and later changed to physics, qualifying for his Diploma in the laboratory of Werner Martienssen. Here he was supervised by Eckhardt Hoenig, and worked along ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daniel Chee Tsui
Daniel Chee Tsui (, born February 28, 1939) is an American physicist. He is currently serving as the Professor of Electrical Engineering, emeritus, at Princeton University. Tsui's areas of research include electrical properties of thin films and microstructures of semiconductors and solid-state physics. Tsui won the Nobel Prize in Physics of 1998 with Robert B. Laughlin and Horst L. Störmer "for their discovery of a new form of quantum fluid with fractionally charged excitations." Biography Tsui was born into a Chinese agricultural family with two illiterate parents in Fanzhuang (Henan) (), Baofeng, Henan, Republic of China, on February 28, 1939. Born in the midst of Second World War, Tsui described his early childhood memories as being "filled with the years of drought, flood and war which were constantly on the consciousness of the inhabitants of my over-populated village." In 1951, Tsui left for Hong Kong to attend Pui Ching Middle School in Kowloon, beginning his forma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topological Quantum Computer
A topological quantum computer is a type of quantum computer. It utilizes anyons, a type of quasiparticle that occurs in two-dimensional systems. The anyons' world lines intertwine to form braids in a three-dimensional spacetime (one temporal and two spatial dimensions). The braids act as the logic gates of the computer. The primary advantage of using quantum braids over trapped quantum particles is in their stability. While small but cumulative perturbations can cause quantum states to decohere and introduce errors in traditional quantum computations, such perturbations do not alter the topological properties of the braids. This stability is akin to the difference between cutting and reattaching a string to form a different braid versus a ball (representing an ordinary quantum particle in four-dimensional spacetime) colliding with a wall. It was proposed by Russian-American physicist Alexei Kitaev in 1997. While the elements of a topological quantum computer originate in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topological Order
In physics, topological order describes a state or phase of matter that arises system with non-local interactions, such as entanglement in quantum mechanics, and floppy modes in elastic systems. Whereas classical phases of matter such as gases and solids correspond to microscopic patterns in the spatial arrangement of particles arising from short range interactions, topological orders correspond to patterns of long-range quantum entanglement. States with different topological orders (or different patterns of long range entanglements) cannot change into each other without a phase transition. Technically, topological order occurs at zero temperature. Various topologically ordered states have interesting properties, such as (1) ground state degeneracy and fractional statistics or non-abelian group statistics that can be used to realize a topological quantum computer; (2) perfect conducting edge states that may have important device applications; (3) emergent gauge field and Fermi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anyon
In physics, an anyon is a type of quasiparticle so far observed only in two-dimensional physical system, systems. In three-dimensional systems, only two kinds of elementary particles are seen: fermions and bosons. Anyons have statistical properties intermediate between fermions and bosons. In general, the operation of exchange symmetry, exchanging two identical particles, although it may cause a global phase shift, cannot affect observables. Anyons are generally classified as ''abelian'' or ''non-abelian''. Abelian anyons, detected by two experiments in 2020, play a major role in the fractional quantum Hall effect. Introduction The statistical mechanics of large many-body systems obeys laws described by Maxwell–Boltzmann statistics. Quantum statistics is more complicated because of the different behaviors of two different kinds of particles called fermions and bosons. In two-dimensional systems, however, there is a third type of particle, called an anyon. In a two-dimens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fermion
In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-integer spin (spin 1/2, spin , Spin (physics)#Higher spins, spin , etc.) and obey the Pauli exclusion principle. These particles include all quarks and leptons and all composite particles made of an even and odd, odd number of these, such as all baryons and many atoms and atomic nucleus, nuclei. Fermions differ from bosons, which obey Bose–Einstein statistics. Some fermions are elementary particles (such as electrons), and some are composite particles (such as protons). For example, according to the spin-statistics theorem in Theory of relativity, relativistic quantum field theory, particles with integer Spin (physics), spin are bosons. In contrast, particles with half-integer spin are fermions. In addition to the spin characteristic, fermions have another specific property: they possess conserved baryon or lepton quantum numbers. Therefore, what is usually referr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
