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Alfred Landé organized the magnetic response of coupled atomic angular momenta. The Landé g-factor relates a magnetic energy shift to the projection of total angular momentum, accounting for both orbital angular momentum and spin. For LS coupling, $g_J=1+[J(J+1)+S(S+1)-L(L+1)]/[2J(J+1)]$ when $J\ne 0$, neglecting the small correction to the electron spin g-factor. For $L=0$ and $J=S=1/2$, it gives $g_J=2$. Different atomic terms therefore split differently in a weak magnetic field.^[ref]

A physicist.^[ref]

Alfred Perot collaborated with Charles Fabry on the Fabry–Pérot interferometer, developed in the late 1890s. Repeatedly reflected light interferes so that transmission is strongest near discrete optical-path resonances. Changing the spacing or propagation angle shifts those resonances, allowing the instrument to compare wavelengths and examine fine spectral lines. Their collaboration made this multiple-beam wave interference into a practical method of high-resolution spectroscopy.^[ref]

Biography: www.larousse.fr/encyclopedie/personnage/Alfred_Perot/103059

A researcher who coauthored atomic-scale studies of metallic nanoparticles using scanning transmission electron microscopy. An aberration-corrected instrument combined images of atomic columns with chemical analysis to investigate gold particles and particles containing two metals. This combination helps distinguish changes in shape from changes in composition, which can look deceptively similar in a single projection.^[ref]

Amnon Yariv and David M. Pepper analyzed phase conjugation through degenerate four-wave mixing. The nonlinear interaction generates a returning light field with the opposite spatial wave phase variation. Under appropriate propagation conditions, this lets the returning wavefront retrace distortions of the incident field. Their 1977 paper treats amplified reflection and a related mode of parametric oscillation, connecting a nonlinear material response with both wavefront control and optical amplification.^[ref]

Anatoly Spitkovsky developed time-dependent calculations of plasma-filled pulsar magnetospheres using the force-free limit, including cases with a tilted magnetic axis. The simulations determine field structure and rotational energy loss while allowing magnetospheric currents and current sheets.^[ref]

Such calculations test the limits of applying a vacuum-dipole picture to a conducting plasma. The approximation neglects plasma inertia where electromagnetic stresses dominate; it does not assert that the plasma is physically absent.

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]

Andre Geim coauthored measurements showing that electric charge carriers in graphene can behave as effectively massless quasiparticles described by the Dirac equation. The 2005 experiments found an unusual sequence of quantum Hall effect plateaus and an oscillation phase associated with Berry phase. Here the Dirac description concerns low-energy quasiparticles in a carbon lattice, rather than free electrons acquiring zero rest mass. The results connect a readily contacted material with concepts usually introduced in relativistic quantum mechanics.^[ref]

A physicist researching condensed matter physics, including graphene.^[ref]

Andrei Linde develops models of cosmic inflation and the transition to the subsequent hot cosmic state. His work with Lev Kofman and Alexei Starobinsky explained how coherent inflaton oscillations can transfer energy through parametric resonance.

In an expanding background the amplification need not follow the simple periodic pattern of a fixed-frequency oscillator. Their study treated successive production events, backreaction and rescattering, establishing when efficient preheating occurs within the model. Producing particles and reaching thermal equilibrium remain distinct stages.^[ref]

Andrei Sakharov connected the cosmic excess of matter over antimatter with microscopic particle reactions. His 1967 paper proposed baryon number violation and CP violation in the expanding early universe as ingredients for generating a baryon asymmetry. The resulting Sakharov conditions also require departure from thermal equilibrium in the usual reaction-based setting: otherwise inverse reactions and symmetry constraints erase the attempted asymmetry. This turns an astronomical abundance question into a test of particle interactions and cosmological history.^[ref]

Andrew G. Truscott measured Fermi pressure in a trapped dilute atomic gas. The experiment compared the spatial distributions of fermionic and bosonic lithium under conditions where their different quantum statistics become important.

Even at low temperature, the Pauli exclusion principle prevents identical fermions from all occupying the lowest one-particle state. Filling higher states gives the trapped cloud a finite extent beyond a classical thermal expectation. The distribution therefore probes degeneracy pressure through the size of a controllable atomic sample.^[ref]

An experimental physicist who investigated how long polymer chains organize into crystals. Studies of thin, plate-like polymer crystals led him to the mechanism of chain folding: a long molecule can turn back repeatedly rather than extend through the entire specimen. The finding connected microscopic chain arrangement with crystal shape and helped establish the structural basis of polymer physics.^[ref]

Andrew R. Liddle coauthored an analysis of when observable perturbations were produced relative to the end of cosmic inflation. It shows why a single universal count of expansion factors is not an assumption-free link between an inflationary model and present observations.^[ref]

The duration and physical conditions after inflation enter the mapping between an observed wavelength and the earlier field evolution. This gives reheating a role in testing a model even when the reheating process is not directly observed.

An experimental optical physicist whose research uses Raman spectroscopy and photoluminescence to investigate materials. Her NIST profile describes combined magneto-Raman and electrical transport measurements: the same sample can be probed optically while its response to a magnetic field is measured electrically. The combination connects vibrational and electronic properties rather than relying on either signal alone.^[ref]

A theoretical physicist studying dynamical approaches to the measurement problem. His review with Giancarlo Ghirardi develops models in which nonlinear and random modifications of the Schrödinger equation account for localization of macroscopic objects while retaining ordinary microscopic predictions to high accuracy. Such models make the transition from quantum behavior to classical behavior part of the dynamics.^[ref]

Anne L'Huillier develops experimental and theoretical methods based on high harmonic generation in gases. The generated extreme ultraviolet light contains many harmonics of the driving laser frequency; their relative spectral phases determine whether they combine into short optical pulses. Her research connects that generation problem with attosecond measurements of electron dynamics following photoionization. The central link is between a controlled optical waveform and the timing information carried by emitted electrons.^[ref]

A physicist who researches high harmonic generation and ultrafast electron dynamics.^[ref]

An experimental condensed matter physicist who coauthored an observation of zero sound in helium-3. The experiment probed a collective density wave in a regime where quasiparticle collisions are slow compared with the oscillation. This distinguishes collisionless quantum-fluid dynamics from ordinary hydrodynamic sound.^[ref]

Anthony Leggett developed a theoretical account of the newly discovered superfluid phases of helium-3. Unlike helium-4 atoms, helium-3 atoms are fermions, so their superfluid state involves correlated pairing. The internal spin and orbital structure of the pairs allows several distinct ordered phases. His account connected this structure with unusual nuclear magnetic resonance observations, using magnetic response to distinguish possible forms of the condensate. The work illustrates how a small interaction can make the internal symmetry of a quantum fluid experimentally visible.^[ref]

A physicist who studied superfluidity and macroscopic quantum mechanics at Illinois.^[ref]

Physicist and author of the 1957 primary magnetic-isotherm criterion now associated with the Arrott plot. The publication identifies affiliations at Carnegie Institute of Technology and Ford Motor Company's Scientific Laboratory; no biographical dates are asserted here.

Antoni Dymanus, Johannes Jacobus van Vaals and Wilhelmus Leonardus Meerts studied potassium cyanide and isotope-substituted variants using molecular beam electric resonance. Rotational frequencies constrain molecular moments of inertia, while isotope substitution changes those moments in a predictable way. Comparing the measured constants therefore tests the proposed geometry. Their resolved rotational and hyperfine structure supported an effective T-shaped molecular structure, rather than assuming a linear arrangement from the chemical formula.^[ref]

A physicist, doctoral supervisor of Johannes Jacobus van Vaals and chapter III coauthor of High Resolution Molecular Beam Study of Alkali Cyanides by Johannes Jacobus van Vaals.^[ref]

Identity: Radboud University identifies Prof. Antoni Dymanus as a physics doctoral supervisor

Anton Zeilinger coauthored an experiment preparing GHZ states of three spatially separated photons. The distinguishing feature is the quantum coherence between the two three-photon alternatives: recording the same populations alone would also be compatible with an incoherent mixture. Measurements in additional polarization bases tested this distinction, making three-party entanglement an experimental resource for investigating local realism.^[ref]

A physicist researching quantum optics and quantum foundations.^[ref]