All articles starting with Q

Quantum Design

Quantum Design is an American scientific instrument maker founded in 1982, best known for the PPMS and MPMS SQUID magnetometer used in materials research labs worldwide.

Quantum diamond microscope

A quantum diamond microscope is a wide-field magnetic imaging instrument that uses nitrogen-vacancy centers in diamond to map magnetic fields, with micron-scale resolution at room temperature.

Quantum diamond microscopy (QDM) is a wide-field magnetic imaging technique using nitrogen-vacancy color centers in a diamond chip to map magnetic fields at room temperature, applied in geoscience, biology, and electronics.

Sep 29, 2026

Quantum digital signature

A quantum digital signature is a cryptographic scheme in which quantum states of light let recipients verify signatures, with security guaranteed by quantum mechanics rather than computational assumptions.

Quantum discord

Quantum discord is a measure of the quantumness of correlations in bipartite quantum systems, introduced by Ollivier and Zurek in 2001, which can be nonzero even without entanglement.

Quantum discrete logarithm algorithms

Quantum discrete logarithm algorithms compute discrete logarithms in groups in polynomial time. Peter Shor gave the first such algorithms in 1994, threatening Diffie–Hellman key exchange and elliptic-curve cryptography.

Quantum dot

A quantum dot, also called an artificial atom, is a nanometer-scale semiconductor crystal, typically 2–20 nm, whose optical properties are set by its size; it lights QLED displays.

Quantum dot array

A quantum dot array is a lattice of nanoscale semiconductor islands, each confining a few electrons, that analog-simulates the Fermi-Hubbard model; a 15,000-site silicon array was shown in 2026.

Quantum dot blinking

Quantum dot blinking, or photoluminescence intermittency, is the random switching of a single semiconductor nanocrystal's light emission between bright and dark states under continuous excitation.

Quantum dot display

A quantum dot display, also called a QLED or nanocrystal display, uses semiconductor nanocrystals to produce or convert light, yielding wider color gamuts than phosphor or organic emitters.

Quantum dot infrared photodetector

A quantum dot infrared photodetector, or QDIP, is an infrared photodetector that uses semiconductor quantum dots as the absorbing region, most often self-assembled InAs dots on GaAs.

Quantum dot infrared upconversion device

A quantum dot infrared upconversion device (QD-UCD) is an optoelectronic device that stacks an infrared photodetector with a visible LED, converting infrared light into visible emission.

Quantum dot laser

A quantum dot laser is a semiconductor laser diode whose gain medium consists of self-assembled InAs nanoscale islands, a concept proposed in 1982 and first demonstrated in 1994.

Quantum dot photocatalysis

Quantum dot photocatalysis is the use of semiconductor nanocrystals a few nanometers across to drive chemical reactions with light, including hydrogen evolution, CO2 reduction, and pollutant degradation.

Quantum dot single-photon sources

A quantum dot single-photon source is a solid-state device in which a single semiconductor quantum dot emits one photon per excitation pulse on demand, developed for photonic quantum computing and communication.

Quantum dot solar cell

A quantum dot solar cell (QDSC) is a third-generation photovoltaic device using semiconductor nanocrystals whose size-tuned bandgaps absorb different parts of the solar spectrum, with certified efficiencies reaching 18.1%.

Quantum dot spin qubit

A quantum dot spin qubit is a quantum bit whose information is stored in the spin of a single electron or hole confined in a semiconductor quantum dot.

Quantum dot spin qubits in CMOS

Quantum dot spin qubits in CMOS are quantum bits encoded in the spin of single electrons confined in silicon quantum dots, fabricated using standard CMOS chip processes.

Quantum dot superlattices

A quantum dot superlattice (QDSL) is an ordered array of quantum dots arranged like atoms in an artificial solid, pursued for engineered electronic bands and band-like transport.

Quantum droplet

Quantum droplets are self-bound clusters of ultracold atoms or molecules that behave like liquids far more dilute than air, predicted and observed in 2015 and 2016.

Quantum droplets in dilute Bose mixtures

Quantum droplets of binary Bose mixtures are self-bound clusters of atoms in two overlapping Bose-Einstein condensates, stabilized by quantum fluctuations, predicted in 2015 and observed in potassium in 2018.

Quantum efficiency

Quantum efficiency is the fraction of incident photons a device converts into electrical signal, typically electrons; in LEDs it analogously measures conversion of charge carriers into photons.

Quantum electrodynamics

Quantum electrodynamics (QED) is the quantum field theory describing how charged particles interact with light through photon exchange; it earned Tomonaga, Schwinger, and Feynman the 1965 Nobel Prize.

Quantum emitter

A quantum emitter is a nanoscale light source, such as an atom, molecule, defect, or quantum dot, that releases one photon at a time on demand.

Quantum emitters in hexagonal boron nitride

Quantum emitters in hexagonal boron nitride (hBN) are atomic-scale defects in the layered semiconductor hBN that emit single photons one at a time, many stably at room temperature.

Quantum emitters in transition metal dichalcogenides

Quantum emitters in transition metal dichalcogenides are defect-like sites in atomically thin semiconductors such as WSe₂ that emit single photons on demand, first demonstrated in monolayer WSe₂ in 2015.

Quantum emitters in two-dimensional materials

Quantum emitters in two-dimensional materials are localized defects in atomically thin crystals that emit light one photon at a time, first identified in monolayer WSe2 by five research teams in 2015.

Quantum entanglement

Quantum entanglement is a property of composite quantum systems whose parts cannot be described independently, showing correlations stronger than classical physics allows; it earned the 2022 Nobel Prize in Physics.

Quantum eraser experiment

The quantum eraser experiment, also called quantum erasure, is an interferometry experiment in which which-path information is erased so interference reappears, proposed by Scully and Drühl in 1982.