All articles starting with Q
2,252 articles
Quantum turbulence
Quantum turbulence, also known as superfluid turbulence, is the turbulent motion of quantum fluids such as superfluid helium, where rotation is carried by quantized vortex lines.
Quantum Turing machine
The quantum Turing machine, also called the universal quantum computer, is a mathematical model of computation generalizing the classical Turing machine, formalized by David Deutsch in 1985.
Quantum twisting microscope
The quantum twisting microscope (QTM) is a scanning probe instrument that resolves electrons in momentum space by scanning the twist angle of an atomically thin tip, demonstrated at the Weizmann Institute in 2023.
Quantum utility
Quantum utility is a quantum computing term, popularized by IBM in 2023, for reliable quantum computation at a scale beyond brute-force classical simulation, weaker than quantum advantage.
Quantum vacuum state
The quantum vacuum state, also called the zero-point field, is the ground state of a quantum field: it holds no particles, yet its fluctuations produce measurable effects like the Casimir force.
Quantum valley Hall effect in silicene
The quantum valley Hall effect in silicene is a predicted transport phenomenon in which electrons of opposite valley index flow to opposite edges of a buckled, one-atom-thick silicon sheet.
Quantum volume
Quantum volume (QV) is a single-number benchmark for quantum computers, introduced by IBM in a 2019 paper. It is the largest square random circuit a machine can run reliably.
Quantum vortex
A quantum vortex, also called a quantized vortex, is a line defect in a superfluid whose circulation is quantized; rotating superfluids form lattices of them.
Quantum walk
A quantum walk is the quantum-mechanical counterpart of a classical random walk, coming in discrete-time and continuous-time forms and powering quantum algorithms for search and graph problems.
Quantum walk with single photons
A quantum walk with single photons is an experiment in which a single photon performs a discrete-time quantum walk, its polarization acting as the quantum coin.
Quantum well
A quantum well is a semiconductor layer a few nanometers thick between wider-bandgap barriers, confining electrons to two dimensions with quantized energy levels, used in quantum well lasers.
Quantum well infrared photodetector
A quantum well infrared photodetector (QWIP) is a semiconductor detector that absorbs infrared photons in quantum wells, first demonstrated in GaAs/AlGaAs in 1987 and used mainly for long-wavelength infrared imaging.
Quantum well laser
A quantum well laser is a semiconductor diode laser with an active layer only a few nanometers thick, giving lower threshold current and narrower emission.
Quantum wire
A quantum wire is a narrow semiconductor conductor, typically under 100 nm wide, where electrons are confined in two directions and move freely only along its length.
Quantum Yang–Baxter equation
The quantum Yang–Baxter equation is a cubic operator equation, R₁₂R₁₃R₂₃ = R₂₃R₁₃R₁₂, introduced by C. N. Yang and R. J. Baxter in 1967 and central to quantum integrable systems.
Quantum yield
Quantum yield (Φ) is a measure of the efficiency of a photochemical or photophysical process, the number of molecules changed or photons emitted per photon absorbed, and can exceed 1 in chain reactions.
Quantum Zeno effect
The quantum Zeno effect is the inhibition of transitions between quantum states by frequent measurement, first demonstrated theoretically in 1977 by Misra and Sudarshan; its converse, the anti-Zeno effect, accelerates decay.
Quantum-behaved particle swarm optimization
Quantum-behaved particle swarm optimization (QPSO) is a metaheuristic for continuous optimization that models particles as quantum entities in a delta potential well, introduced by Jun Sun, Bin Feng, and Wenbo Xu in 2004.
Quantum-class cruise ship
The Quantum class is a class of five cruise ships built by Meyer Werft for Royal Caribbean International from 2014, introducing firsts such as robotic bartenders and skydiving simulators.
Quantum-confined Stark effect
The quantum-confined Stark effect (QCSE) is the shift and weakening of exciton absorption in a quantum well under an applied electric field, named in 1984.
Quantum-enhanced Raman microscopy
Quantum-enhanced Raman microscopy is a chemical imaging technique that uses squeezed light to reduce noise below the shot-noise limit, improving Raman microscope sensitivity without extra sample power.
Quantum-inspired optimization
Quantum-inspired optimization is a class of classical algorithms borrowing quantum phenomena such as superposition, tunneling, and annealing to solve optimization problems, running entirely on conventional hardware.
Quantum-Si
Quantum-Si is a Connecticut life-sciences instrument company founded in 2013 by Jonathan Rothberg and listed on Nasdaq as QSI in 2021, known for its Platinum benchtop single-molecule protein sequencer.
Quantum-to-classical transition
The quantum-to-classical transition is the problem of how classical behavior with definite properties emerges from quantum mechanics, its leading account being environment-induced decoherence, first proposed by H. Dieter Zeh.
QuantumDiamonds
QuantumDiamonds GmbH is a Munich deep-tech startup, founded in 2022 as a spin-off of the Technical University of Munich, that builds diamond quantum sensors for chip inspection.
QuantumScape
QuantumScape is a San Jose, California battery company founded in 2010 that develops anode-free solid-state lithium-metal battery cells for electric vehicles, licensed to Volkswagen's PowerCo.
QuantWare
QuantWare is a Dutch quantum-hardware startup in Delft, founded in 2021 as a QuTech spinout, that builds superconducting quantum processors on its VIO open architecture and runs foundry services.
Quanyin Hu
Quanyin Hu is a drug delivery and nanomedicine researcher who engineers platelets and cell derivatives as vehicles for cancer immunotherapy, leading the CIPT Laboratory at the University of Wisconsin–Madison School of Pharmacy.
Quanzhen Daoism
Quanzhen Daoism (全真道), the Way of Complete Perfection, is a celibate monastic Daoist order from North China, built around monasteries and internal alchemy, which flourished under the Mongols and Yuan dynasty.
Quanzhen School
The Quanzhen School (全真教) is a Daoist school founded under the Jin dynasty, favored by the Mongols under patriarch Qiu Chuji and still recognized alongside the Zhengyi school today.