42,772 articles
Ensemble effect in single-atom alloys
The ensemble effect in single-atom alloys is the principle that a catalytic reaction may require a specific number of adjacent atoms of one metal, which dilution controls.
Ensemble empirical mode decomposition
Ensemble empirical mode decomposition (EEMD) is a noise-assisted signal-processing method introduced by Zhaohua Wu and Norden Huang in 2009 that cures EMD's mode mixing by averaging many noise-added runs.
Ensemble forecasting
Ensemble forecasting is a weather and climate prediction method that runs a numerical model many times with varied initial conditions, yielding probabilities instead of a single forecast.
Ensemble Kalman filter
The ensemble Kalman filter (EnKF) is a Monte Carlo implementation of the Kalman filter for high-dimensional, nonlinear state estimation, proposed by Geir Evensen in 1994 for ocean modeling.
Ensemble transform Kalman filter
The ensemble transform Kalman filter (ETKF) is a deterministic square-root Kalman filter, introduced in 2001, that assimilates observations into a forecast ensemble without perturbing observations.
Enstatite
Enstatite is a rock-forming silicate mineral of the pyroxene group with ideal formula Mg2Si2O6, occurring chiefly in ultramafic igneous rocks and dominant in the enstatite chondrite meteorites.
Ent-Kaurene
Ent-kaurene is a tetracyclic diterpene hydrocarbon with the formula C20H32, formed from geranylgeranyl diphosphate in plant plastids and serving as the universal precursor of gibberellin hormones and ent-kaurane natural products.
Entangled photon pair
An entangled photon pair is a pair of photons whose joint quantum state cannot be written as a mixture of product states, typically produced by spontaneous parametric down-conversion.
Entangled photon source
An entangled photon source is a device producing photon pairs whose quantum states are strongly correlated, most often by spontaneous parametric down-conversion in a nonlinear crystal pumped by a laser.
Entanglement (polymer physics)
Entanglement in polymer physics is a topological constraint in which long, flexible polymer chains that cannot cross through one another restrict each other's motion and relaxation.
Entanglement catalysis
Entanglement catalysis (quantum catalysis) is a quantum information phenomenon where an entangled catalyst state enables otherwise impossible transformations, returned unchanged, introduced by Jonathan and Plenio in 1999.
Entanglement distillation
Entanglement distillation, also called entanglement purification, is a quantum information protocol that turns many noisy entangled pairs into fewer near-perfect ones, enabling faithful quantum teleportation through noisy channels.
Entanglement dynamics in open quantum systems
Entanglement dynamics in open quantum systems is the study of how environmental noise generates and degrades entanglement, which can vanish at a finite time, unlike ordinary decoherence.
Entanglement forging and circuit knitting
Entanglement forging is a quantum-classical technique representing a 2N-qubit state with N qubits plus classical computation, first demonstrated on water by IBM Quantum in 2022.
Entanglement in continuous-variable systems
Entanglement in continuous-variable systems is the nonseparability of bosonic modes such as optical field modes, whose entanglement is carried by continuous quadratures like position and momentum.
Entanglement in many-body quantum systems
Entanglement in many-body quantum systems studies how entanglement is distributed and structured across many interacting particles, using tools like entanglement entropy, the entanglement spectrum, and topological entanglement entropy.
Entanglement light cone
The entanglement light cone is the region within which quantum entanglement can spread in a many-body system by a given time, bounded by Lieb-Robinson velocity.
Entanglement measure
An entanglement measure is a function assigning a nonnegative number to a quantum state to quantify its entanglement, vanishing on separable states and normalized on maximally entangled pairs.
Entanglement of formation
The entanglement of formation (EoF) is a measure of quantum entanglement for a bipartite quantum state, defined as the minimum average entanglement over all pure-state ensembles representing the mixed state.
Entanglement of ultracold molecules
Entanglement of ultracold molecules is the creation of quantum correlations between molecules cooled near absolute zero in optical traps, first demonstrated between individually controlled molecules in 2023.
Entanglement sudden death
Entanglement sudden death is the abrupt disappearance of quantum entanglement in a noisy environment after a finite time, unlike ordinary decoherence, which decays only gradually and never reaches zero.
Entanglement swapping
Entanglement swapping is a quantum communication protocol, proposed in 1993 and demonstrated in 1998, that entangles two particles that never interacted via a Bell-state measurement, underpinning quantum repeaters.
Entanglement wedge reconstruction
Entanglement wedge reconstruction is a theorem in the AdS/CFT correspondence stating that bulk operators in a boundary region's entanglement wedge can be reconstructed as operators on that region.
Entanglement witness
An entanglement witness is a Hermitian observable used to certify quantum entanglement. It is a practical alternative to full state tomography, using negative expectation values to prove entanglement.
Entanglement-assisted classical capacity
The entanglement-assisted classical capacity, C_E, of a quantum channel is the maximum reliable classical bit rate with unlimited shared entanglement, characterized by Bennett, Shor, Smolin, and Thapliyal in 1999.
Entanglement-assisted distributed quantum sensing
Entanglement-based distributed quantum sensing is a measurement technique in which spatially separated sensors share quantum entanglement, letting the network estimate a quantity beyond the precision of classical sensors.
Entanglement-based quantum key distribution
Entanglement-based quantum key distribution (entanglement-based QKD) is a form of quantum key distribution in which two parties measure entangled photon pairs, letting the correlations certify the key without a trusted source.
Entecavir
Entecavir, sold as Baraclude, is a carbocyclic guanosine analog that inhibits the hepatitis B virus reverse transcriptase and is a first-line oral treatment for chronic hepatitis B.
Enteroglucagon
Enteroglucagon, or gut glucagon, is a collective term for glucagon-related peptides made by intestinal L cells from proglucagon, including glicentin, oxyntomodulin, GLP-1, and GLP-2, first named in 1968.
Enthalpy
Enthalpy, symbol H, is a thermodynamic state function defined as internal energy plus pressure times volume, H = U + PV; its change equals heat at constant pressure.