A physicist who studied ruby fluorescence for high-pressure measurements.^[ref]

A physicist who investigated spectroscopy and ruby fluorescence under pressure.^[ref]

Yakir Aharonov and David Bohm showed how scalar potentials and vector potentials can affect quantum interference even when a charged particle travels through a region with vanishing magnetic field. In the ideal magnetic arrangement, two paths enclose a confined magnetic flux $\Phi$, and their relative quantum phase changes by $q\Phi /\hslash$ for charge $q$. This makes the observable interference shift sensitive to the enclosed flux and the geometry of the paths, rather than only the local magnetic force along either path.^[ref]

A physicist researching quantum theory and the Aharonov-Bohm effect.^[ref]

Akira Tonomura used electron holography to test the Aharonov-Bohm effect with magnetic flux confined away from the electron paths. A coated magnetic toroid let electron waves pass through its hole and outside it while a superconducting shield excluded the magnetic field from those paths. The measured relative phase still depended on the enclosed flux. The experiment isolates a quantum phase effect that cannot be inferred from the local classical magnetic force along either path.^[ref]

A physicist who developed electron holography and investigated the Aharonov-Bohm effect.^[ref]

Pascual Jordan and Max Born helped turn the new quantum mechanics into a systematic matrix calculus. In this description, a position operator and a momentum operator generally do not commute; the canonical rule is $[q,p]=i\hslash I$. The order of multiplication therefore carries physical information, rather than being a notational detail. Their 1925 paper developed the mathematical rules connecting these noncommuting quantities with the dynamics and transition frequencies of quantum systems.^[ref]

A physicist who developed matrix mechanics and held a professorship in theoretical physics at Hamburg.^[ref]

August Kundt made standing wave patterns of sound waves visible through the dust patterns in Kundt's tube. Neighboring repeat marks in the ideal pattern are separated by half a wavelength, so a measured spacing $d$ and known frequency $f$ give speed of sound $c=2fd$. The tube turns an oscillation too rapid to follow directly into a spatial ruler. Comparing resonance conditions in a solid rod and a gas also connects the method with measurements of sound propagation in different materials.^[ref]

A physicist whose appointments took him from Zürich in 1868 through Würzburg and Strasbourg to the Berlin chair of experimental physics in 1888.^[ref]

A physicist appointed to the Paris Observatory in 1855 who developed telescopes.^[ref]

An experimental optical physicist who measured the Sagnac effect with a rotating interferometer. Beams traveling around the same closed path in opposite directions acquire a rotation-dependent phase difference. His apparatus mounted the source and optical components on a rotating plate, connecting a fringe displacement to rotation; his ether interpretation must be distinguished from the observed effect itself.^[ref]

Wander Johannes de Haas and Albert Einstein investigated mechanical motion produced by changing the magnetization of a suspended body. Magnetic reversal changes microscopic angular momentum; a compensating rotation of the body tests angular-momentum conservation. Their experiment connected an apparently internal magnetic property with a visible mechanical response. Interpreting a gyromagnetic measurement requires the relation between magnetic moment and angular momentum, rather than treating magnetization as a force acting independently of its microscopic carriers.^[ref]

A physicist who researched magnetism and became a professor at Leiden in 1924.^[ref]

Anders Jonas Ångström developed quantitative optical spectroscopy, including precise measurements of the solar spectrum. His 1868 study measured the wavelengths of Fraunhofer lines, turning reproducible spectral landmarks into numerical standards. The ångström, $10^{-10}$ metres, bears his name. Such calibrated wavelength measurements let observations made with different instruments be compared, helping move spectroscopy from descriptions of colour to tests of material composition and physical models.^[ref]

A physicist appointed professor at Uppsala in 1858, whose research included spectroscopy.^[ref]

An experimental optical physicist who coauthored measurements of the spatial coherence of three bright stars. Separate telescopes recorded intensity fluctuations whose correlations depend on their separation, applying stellar intensity interferometry to angular measurements. The approach links a laboratory quantum-optics correlation to a stellar observation.^[ref]

An experimental optical physicist who coauthored stellar stellar intensity interferometry work, publishing under the surname Fouché. The experiment correlated fluctuations of starlight recorded by separate telescopes, applying the Hanbury Brown and Twiss effect to astronomical observations.^[ref][ref]

An experimental optical physicist who coauthored stellar stellar intensity interferometry measurements. Correlating fluctuations detected at separated telescopes probes the spatial coherence of starlight. The method extracts angular information from photon statistics rather than requiring the optical electric fields from the telescopes to remain phase locked.^[ref]

Robin Kaiser studies collective scattering of light and coherent transport in clouds of cold chemical atoms. His ANDLICA project asks whether Anderson localization of light can be observed in three-dimensional cold ytterbium samples. The project distinguishes localization from effects such as absorption and inelastic scattering of light, which can imitate some transport signatures. It connects controlled atomic samples and time-resolved measurements with the physical question of whether disorder can prevent extended wave transport.^[ref]

A physicist.^[ref]

Clinton Davisson and Lester Germer measured strong angular structure in electron scattering from a nickel crystal. Its dependence on incident electron energy agreed with a wavelength set by the electron momentum through the de Broglie wavelength. The crystal therefore supplied a periodic structure against which electron wave behavior could be tested. The Davisson–Germer experiment linked a tunable electron source and angularly resolved detector with the theoretical idea of matter waves.^[ref]

A physicist whose route into research included a telephone-company job when he could not afford to continue at Chicago. He later worked at Bell Telephone Laboratories, retiring in 1946 after 29 years, and taught physics at Virginia in 1947–1949.^[ref] The Davisson–Germer experiment connects that industrial-laboratory work to electron diffraction and matter waves.

A physicist associated with the Barkhausen effect: the magnetization of a ferromagnet can change in discrete jumps even when the applied magnetic field varies smoothly. A pickup coil detects the accompanying changes in magnetic flux; amplification makes the irregular signal audible. The experiment connects a macroscopic noise measurement with sudden rearrangements of magnetic domains and the motion of domain walls.^[ref] His work at Dresden also developed the experimental teaching of electrical engineering.^[ref]

A physicist responsible for magnetism, materials and spintronics research at INRiM in 2023.^[ref]

Stefano Zapperi and Gianfranco Durin studied the statistics of Barkhausen effect avalanches in soft ferromagnets. Slowly changing the applied magnetic field produces bursts of magnetization as pinned domain walls move. Their 2000 work measured avalanche-size distributions in polycrystalline and amorphous materials and found distinct scaling classes in the slow-drive limit. Interpreting the data through the release of pinned domain walls connects irregular magnetic noise with a collective phase transition, including a quantitative relation between the distribution cutoff and the demagnetizing factor.^[ref]

A physicist and professor of theoretical physics of matter at Milan.^[ref]

Walter Schottky explained a fundamental source of electrical noise: even a steady mean electric current can fluctuate because charge arrives in discrete units. His 1918 paper studies intrinsic limits to detecting weak signals with amplifying tubes, distinguishing charge discreteness from thermal motion. For independent charge-transfer events, the modern shot noise relation is $S_I=2eI$ for the one-sided current-noise power spectral density. Its dependence on the mean current $I$ makes the noise a probe of charge-transfer statistics, rather than merely a defect of an amplifier.^[ref]

A physicist who held a theoretical-physics professorship at Rostock from 1923 to 1927.^[ref]

Samuel Jackson Barnett demonstrated that mechanical rotation can magnetize a material, the Barnett effect. Rotation couples to the angular momentum associated with microscopic magnetic moments, producing a magnetic response without using an applied field as the driving cause. The effect connects mechanical angular momentum with magnetization and complements experiments in which a change of magnetization produces mechanical motion. It makes the magnetic moment's connection with microscopic angular momentum experimentally accessible.^[ref]

A physicist listed as professor of physics at the University of California, Los Angeles, in its 1927–1928 faculty announcement.^[ref]