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Yoshihisa Yamamoto (scientist)
is the director of Physics & Informatics Laboratories (PHI Labs), NTT Research, Inc. He is also Professor (Emeritus) at Stanford University and National Institute of Informatics (Tokyo). Biography Yamamoto was born in Tokyo on November 21, 1950. In 1973 he received his B.S. degree from Tokyo Institute of Technology. He continued his studies at the University of Tokyo where he received his M.S. in 1975 and Ph.D. in 1978. From 1978 to 1992, he worked at NTT Basic research, Basic Research Laboratories in Tokyo. Since 1992, he has been a professor of applied physics and electrical engineering at Stanford University in the United States and currently a professor (emeritus). Since 2003, he also has been a professor at National Institute of Informatics in Tokyo and currently a professor (emeritus). In 2019, he became a founding director of NTT PHI Labs in Silicon Valley, California, the United States. Work Yamamoto's scientific focuses in the 1980s were fiber-optic communication, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tokyo
Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most populous urban areas in the world. The Greater Tokyo Area, which includes Tokyo and parts of six neighboring Prefectures of Japan, prefectures, is the most populous metropolitan area in the world, with 41 million residents . Lying at the head of Tokyo Bay, Tokyo is part of the Kantō region, on the central coast of Honshu, Japan's largest island. It is Japan's economic center and the seat of the Government of Japan, Japanese government and the Emperor of Japan. The Tokyo Metropolitan Government administers Tokyo's central Special wards of Tokyo, 23 special wards, which formerly made up Tokyo City; various commuter towns and suburbs in Western Tokyo, its western area; and two outlying island chains, the Tokyo Islands. Although most of the w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stanford University
Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth List of governors of California, governor of and then-incumbent List of United States senators from California, United States senator representing California) and his wife, Jane Stanford, Jane, in memory of their only child, Leland Stanford Jr., Leland Jr. The university admitted its first students in 1891, opening as a Mixed-sex education, coeducational and non-denominational institution. It struggled financially after Leland died in 1893 and again after much of the campus was damaged by the 1906 San Francisco earthquake. Following World War II, university Provost (education), provost Frederick Terman inspired an entrepreneurship, entrepreneurial culture to build a self-sufficient local industry (later Silicon Valley). In 1951, Stanfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ataç İmamoğlu
Ataç İmamoğlu (born August 12, 1964) is a Turkish-Swiss physicist working on quantum optics and quantum computation. His academic interests are quantum optics, semiconductor physics, and nonlinear optics. Education İmamoğlu graduated from TED Ankara College in 1981. He received his BSc in electrical engineering at the Middle East Technical University, and his Ph.D. from Stanford for his work on ''Electromagnetically Induced Transparency and Lasers without Inversion.'' He did post-doctoral work on '' atomic and molecular physics'' at Harvard. Career In 1993, he joined the Electrical and Computer Engineering Department of University of California, Santa Barbara. In 1999, he became a professor of electrical engineering and physics. In 2001 he moved to the University of Stuttgart in Germany. Since 2002, he has been working at ETHZ (Swiss Federal Institute of Technology), Switzerland, where he is heading the research group on Quantum Photonics. His group at ETHZ investiga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biexciton
In condensed matter physics, biexcitons are created from two free excitons, analogous to di-positronium in vacuum. Formation of biexcitons In quantum information and computation, it is essential to construct coherent combinations of quantum states. The basic quantum operations can be performed on a sequence of pairs of physically distinguishable quantum bits and, therefore, can be illustrated by a simple four-level system. In an optically driven system where the , 0 1 \rangle and , 1 0 \rangle states can be directly excited, direct excitation of the upper , 1 1 \rangle level from the ground state , 0 0 \rangle is usually forbidden and the most efficient alternative is coherent nondegenerate two-photon excitation, using , 0 1 \rangle or , 1 0 \rangle as an intermediate state. Observation of biexcitons Three possibilities of observing biexcitons exist: (a) excitation from the one-exciton band to the biexciton band (pump-probe experiments); (b) two-photon absorption o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bose–Einstein Condensation Of Polaritons
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”. Overview Polaritons are bosonic quasiparticles which can be thought of as dressed photons. In an optical cavity, photons have an effective mass, and when the optical resonance in a cavity is brought near in energy to an electronic resonance (typically an exciton) in a medium inside the cavity, the photons become strongly interacting, and repel each other. They therefore act like atoms which can approach equilibrium due to their collisions with each other, and can undergo Bose-Einstein condensation (BEC) at high density or low temperatu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-photon Source
A single-photon source (also known as a single photon emitter) 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 (or number 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. Photons from an ideal single-photon source exhibit quantum mechanical characteristics. These characteristics include photon antibunching, so that the time between two successive photons is never less than some minimum value. This behaviour is normally demonstrated by using a beam splitter to direct about half of the incident photons toward one avalanche photodiode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavity Quantum Electrodynamics
Cavity Quantum Electrodynamics (cavity QED) is the study of the interaction between light confined in a reflective cavity and atoms or other particles, under conditions where the quantum nature of photons is significant. It could in principle be used to construct a quantum computer. The case of a single 2-level atom in the cavity is mathematically described by the Jaynes–Cummings model, and undergoes vacuum Rabi oscillations , e\rangle, n-1\rangle\leftrightarrow, g\rangle, n\rangle, that is between an excited atom and n-1 photons, and a ground state atom and n photons. If the cavity is in resonance with the atomic transition, a half-cycle of oscillation starting with no photons coherently swaps the atom qubit's state onto the cavity field's, (\alpha, g\rangle+\beta, e\rangle), 0\rangle\leftrightarrow, g\rangle(\alpha, 0\rangle+\beta, 1\rangle), and can be repeated to swap it back again; this could be used as a single photon source (starting with an excited atom), or as an in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Computer
A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of both particles and waves, and quantum computing takes advantage of this behavior using specialized hardware. Classical physics cannot explain the operation of these quantum devices, and a scalable quantum computer could perform some calculations exponentially faster than any modern "classical" computer. Theoretically a large-scale quantum computer could break some widely used encryption schemes and aid physicists in performing physical simulations; however, the current state of the art is largely experimental and impractical, with several obstacles to useful applications. The basic unit of information in quantum computing, the qubit (or "quantum bit"), serves the same function as the bit in classical computing. However, unlike a classical bit, which can be in one of two states (a binary), a qubit can exist in a superposition of its two " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Optics
Quantum optics is a branch of atomic, molecular, and optical physics and quantum chemistry that studies the behavior of photons (individual quanta of light). It includes the study of the particle-like properties of photons and their interaction with, for instance, atoms and molecules. Photons have been used to test many of the counter-intuitive predictions of quantum mechanics, such as entanglement and teleportation, and are a useful resource for quantum information processing. History Light propagating in a restricted volume of space has its energy and momentum quantized according to an integer number of particles known as photons. Quantum optics studies the nature and effects of light as quantized photons. The first major development leading to that understanding was the correct modeling of the blackbody radiation spectrum by Max Planck in 1899 under the hypothesis of light being emitted in discrete units of energy. The photoelectric effect was further evidence of thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Nondemolition Measurement
Quantum nondemolition (QND) measurement is a special type of measurement of a quantum system in which the uncertainty of the measured observable does not increase from its measured value during the subsequent normal evolution of the system. This necessarily requires that the measurement process preserves the physical integrity of the measured system, and moreover places requirements on the relationship between the measured observable and the self-Hamiltonian of the system. In a sense, QND measurements are the "most classical" and least disturbing type of measurement in quantum mechanics. Most devices capable of detecting a single particle and measuring its position strongly modify the particle's state in the measurement process, e.g. photons are destroyed when striking a screen. Less dramatically, the measurement may simply perturb the particle in an unpredictable way; a second measurement, no matter how quickly after the first, is then not guaranteed to find the particle in the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Amplifier
An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. An optical amplifier may be thought of as a laser without an optical cavity, or one in which feedback from the cavity is suppressed. Optical amplifiers are important in optical communication and laser physics. They are used as optical repeaters in the long distance fiber-optic cables which carry much of the world's telecommunication links. There are several different physical mechanisms that can be used to amplify a light signal, which correspond to the major types of optical amplifiers. In doped fiber amplifiers and bulk lasers, stimulated emission in the amplifier's gain medium causes amplification of incoming light. In semiconductor optical amplifiers (SOAs), electron–hole recombination occurs. In Raman amplifiers, Raman scattering of incoming light with phonons in the lattice of the gain medium produces photons coherent with th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiber-optic Communication
Fiber-optic communication is a form of optical communication for transmitting information from one place to another by sending pulses of infrared or visible light through an optical fiber. The light is a form of carrier wave that is modulated to carry information. Fiber is preferred over electrical cabling when high bandwidth, long distance, or immunity to electromagnetic interference is required. This type of communication can transmit voice, video, and telemetry through local area networks or across long distances. Optical fiber is used by many telecommunications companies to transmit telephone signals, internet communication, and cable television signals. Researchers at Bell Labs have reached a record bandwidth–distance product of over kilometers per second using fiber-optic communication. Background First developed in the 1970s, fiber-optics have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
