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The effective density of states of a parabolic semiconductor band is its density of states integrated against a thermal Boltzmann factor measured from its edge. For one spin-degenerate valley,These quantities have units of number per volume, unlike the energy-resolved density of states. In a nondegenerate semiconductor, $n=N_c{e}^{-(E_c-\mu )/(k_{B}T)}$ and $p=N_v{e}^{-(\mu -E_v)/(k_{B}T)}$; multiple equivalent valleys add their contributions.

A quantum dot confines electrons and electron holes in all three spatial directions, producing discrete energy levels. A semiconductor island surrounded by a larger-band gap material is one realization. Its optical excitation and electron-hole recombination depend on confinement, Coulomb interactions and electric-dipole selection rules.

Indium arsenide, InAs, is a III-V semiconductor. An InAs island in a larger-gap host can provide quantum confinement for electrons and electron holes. The optical transition energy of a strained, confined island is not simply the bulk material's band gap.

Indium antimonide is a narrow-gap semiconductor made of indium and antimony, with chemical formula $\mathrm{InSb}$. Its small band gap permits absorption of comparatively low-energy infrared photons, making it useful in infrared detection.

For an ideal interband threshold, $hc/\lambda$ must reach the gap; actual detector response also depends on optical coupling, carrier collection and temperature. Thermal excitation across a small band gap can supply unwanted carriers, so an operating detector's dark current is an essential measurement alongside quantum efficiency. ^[ref]

A liquid that produces particle scintillation when deposited energy excites its components. Photomultipliers can convert the emitted light into detector pulses.

A quantum computer is a physical device that performs controlled quantum computation and extracts an output through quantum measurement. A programmable quantum computer combines physical qubits, control hardware and classical processing that specifies operations and interprets repeated measurements.

David P. DiVincenzo organized the central physical requirements into five capabilities: scalable and characterized qubits; initialization in a known quantum state; sufficiently long relevant decoherence times compared with operation times; a universal set of quantum gates; and quantum measurement of selected qubits. These requirements connect an abstract quantum circuit with an experiment: knowing the intended gate sequence is useful only if the apparatus can initialize, control and read the encoded system accurately.^[ref]

The encoding can use different physical systems. Two selected internal levels of a trapped ion, for example, can represent the basis states of a qubit. The remaining levels and environmental couplings then become part of the physical control problem.

Ubiquitin is a small protein attached to other proteins in cellular sorting and regulation, including targeting many substrates to a proteasome.

A proteasome is a protein complex that carries out proteolysis; unlike a lysosome, it has no surrounding lipid bilayer.

Hemoglobin is an oxygen-binding protein; its oxygenation can supply a spectroscopic molecular oxygen readout, as in the early Hill reaction work.

A ribonucleoprotein is an association of RNA with proteins.

Nucleoplasmin is a nuclear protein used in the nuclear pore localization experiment.

Its targeting information helped establish that a protein sequence can direct selective nuclear accumulation. Nuclear localization can therefore be tested by comparing intact and altered targeting sequences rather than inferring transport from protein size alone. ^[ref]

An importin is a protein involved in selective import through a nuclear pore complex.

It recognizes suitable cargo directly or through adaptors and participates in passage through the selective pore environment. Directionality depends on the Ran nucleotide cycle and compartment-specific interactions rather than on a permanently one-way opening. ^[ref]

Myosin is a family of actin-associated motor proteins that couple ATP hydrolysis to mechanical work. Family members contribute to muscle contraction, intracellular cargo movement and cortical force generation. Most characterized myosins move toward the actin plus end, while myosin VI provides a notable opposite-direction example. Multiple heads or assemblies can coordinate attachment and stepping, so a single motor-domain reaction does not alone specify whole-filament motion. ^[ref][ref]

An electron carrier protein in the mitochondrial respiratory chain.

It carries electrons between respiratory complexes through reversible changes in its heme iron. Its release from the mitochondrial intermembrane space also contributes to apoptosis in many animal cells, illustrating distinct functions determined by location. ^[ref]

Aprotinin is a small disulfide-stabilized protein that inhibits selected serine proteases, including trypsin-like enzymes. It illustrates a protein inhibitor that blocks access or productive interaction at a protease active site rather than being a general inhibitor of all proteolysis. Its compact, crosslinked structure also makes it a useful model for studying folding and molecular stability. ^[ref]

A peptide comprises amino acid residues joined through peptide bonds.

Ovalbumin is a major protein of chicken egg white with a storage role. It is distinct from serum albumin despite the related names. Its solubility and abundance make it a convenient experimentally recognized protein, including the historical binding comparison discussed under Papain digestion of IgG. ^[ref]

A globin is a member of a protein family with a characteristic fold commonly supporting a heme group. Hemoglobin and myoglobin provide familiar examples involved in oxygen transport and storage. Similar folds can support different physiological roles, so identifying a globin sequence does not by itself specify an oxygen-transport function. Heme coordination and the surrounding protein environment jointly shape ligand binding. ^[ref]

A whey protein used as a model solute in studies of protein association and transport. Its effective electric charge, association state and hydrodynamic radius depend on solution conditions. In a specified spherical-particle model, its electrophoretic mobility and sedimentation speed depend on its charge and buoyant mass through the same Stokes drag law.

Polymer physics connects the conformations and motion of long molecules to the properties of a material. A polymer can change shape through many segment rotations while its chemical backbone remains intact. This makes the competition between flow and relaxation important: the same chain can behave as a coil in one experiment and an extended object in another. Soft matter includes both these flexible structures and liquid crystals, whose orientational order produces a different route to strong mechanical and optical response.