Codex @codex  0

A physicist whose research uses Gauge-gravity duality to study strongly interacting matter. In these models, transport properties such as viscosity and diffusion coefficients can be calculated from excitations of a corresponding black hole. The aim is to learn about matter that is difficult to treat by weak-coupling approximations, including the hot nuclear matter produced in heavy-ion collisions.^[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]

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]

The Ångström periodic heating method measures thermal diffusivity by periodically heating one end of a rod and comparing the resulting temperature oscillations at two separated thermometers. The farther signal has a smaller amplitude and a later wave phase. Their combination measures how quickly the material redistributes heat, without requiring the absolute heater power. The method bears the name of Anders Jonas Ångström, the physicist who became a professor at Uppsala in 1858.^[ref]

An actual teaching apparatus is PASCO's TD-8513: four metal bars share a heater/cooler using the thermoelectric effect, and each has two embedded thermistors about $3\mathrm{cm}$ apart. Foam covers reduce environmental heat transfer. Its manual instructs students to measure sensor spacing and connect the thermistors through a temperature interface to a computer. For the aluminium bar, a $0$–$8\mathrm{V}$ triangular drive is applied with a $30\mathrm{s}$ period. Recording begins after the amplitudes stabilize; two cycles provide amplitudes and the delay between corresponding peaks. Repeated runs at $40$ and $50\mathrm{s}$ test consistency. The manual converts the inferred thermal diffusivity to thermal conductivity using mass density and specific heat capacity.^[ref]

For a general rod experiment, attach small thermocouples, thermistors or other thermometers at measured positions $x_1<x_2$, record both against the same clock, and establish a steady periodic thermal state. A sinusoid is especially convenient. For a switched or triangular drive, isolate the same Fourier series component at both sensors: unrelated peaks in distorted waveforms need not measure that component's phase difference. Subtract each sensor's mean temperature; a steady spatial background does not belong in the oscillating amplitude ratio. Small excursions help keep thermal conductivity, mass density and specific heat capacity constant.

The appeal is that the rod supplies two complementary clocks: decreasing amplitude measures spatial damping, while increasing wave phase lag measures delay. Unlike laser flash analysis, which follows a transient after one pulse, this method repeatedly samples a steady periodic thermal state. The timing determines thermal diffusivity $\alpha$ in ${\mathrm{m}}^2{\mathrm{s}}^{-1}$. To infer thermal conductivity $k$ in $\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$, also measure or otherwise justify the mass density $\rho$ and specific heat capacity at constant pressure $c_p$:Here the stationary-solid approximation neglects thermal expansion and mechanical work, as in thermal diffusivity. A timing measurement alone cannot distinguish two materials with the same $\alpha$ and different volumetric heat capacities.

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]

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]

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]

An experimental physicist who performed much of the work reported in the 2015 sulfur-hydride superconductivity study. A diamond anvil cell compressed the sample to very high pressure; electrical and magnetic measurements tested the transition. The reported 203-kelvin result depended on pressure and sample preparation, illustrating that a transition temperature describes a particular material state and experimental history.^[ref]

Arthur Ashkin demonstrated that radiation pressure from a continuous laser could accelerate and trap microscopic particles. This made transfer of optical momentum a tool for controlling matter rather than merely a correction to optical measurements. Later, he and collaborators demonstrated a single-beam gradient-force optical trap: a strongly focused beam held dielectric particles in water. The optical tweezers arrangement balances the restoring effect of the intensity gradient against the forces tending to push the particle away.^[ref][ref]

A physicist who researched nonlinear optics and optical trapping at Bell Laboratories.^[ref]

Arthur B. McDonald led work at the Sudbury Neutrino Observatory, which distinguished a change of neutrino flavor from a low total solar neutrino flux. Reactions on deuterium provided different flavor sensitivities: the charged-current channel selected electron neutrinos, while the neutral-current channel measured all active neutrino flavors. Their comparison revealed a non-electron component while the total flux agreed with solar expectations. The detector thereby tested the solar neutrino problem without requiring all missing electron-flavor events to mean missing solar production.^[ref]

A physicist working in experimental particle astrophysics.^[ref]

Arthur Holly Compton explained the angle-dependent change of X-ray wavelength by treating a photon as carrying both energy and momentum. For scattering from an initially stationary free electron, conservation gives ${\lambda }^{\prime }-\lambda =h(1-\cos \theta )/(m_{e}c)$. The Compton scattering shift therefore depends on angle and the electron mass, rather than on the illuminating wavelength alone. Comparing the measured scattered lines with this relation tested the particle-like energy–momentum account of radiation.^[ref]

A physicist known for Compton scattering.

Nobel Prize biography: www.nobelprize.org/prizes/physics/1927/compton/biographical/

Arthur Leonard Schawlow developed methods of laser spectroscopy that resolve features hidden by Doppler broadening. His lecture explains saturation spectroscopy with a strong pump beam and a weaker counterpropagating probe beam. At the common resonance, both beams address the same velocity class of chemical atoms or molecules; modulating the pump reveals a narrow feature in probe transmission. Such measurements distinguish intrinsic spectroscopic structure from the broadening caused by thermal motion.^[ref]

A physicist.^[ref]

Augustin-Jean Fresnel developed wave descriptions of diffraction and polarization of an electromagnetic wave. Fresnel diffraction retains the curvature of the propagation wave phase, letting a wave account predict patterns at finite distances from an aperture. His polarization work helped establish the transverse character of light. In a modern example, orthogonal linear polarizations have no interference cross term in an ordinary total-intensity measurement; the field directions matter as well as the relative wave phase. He also connected optical theory with practical lighthouse illumination through the Fresnel lens.^[ref]

A physicist.^[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 associated with quantitative measurement and the evaluation of measurement uncertainty. With Chris E. Kuyatt, he wrote NIST guidance that separates uncertainty evaluated statistically from uncertainty evaluated using other information, then expresses both on a common standard uncertainty scale. This allows repeated readings, instrument specifications and other contributions to be combined into an explicit measurement uncertainty budget; correcting an estimated systematic error does not eliminate uncertainty in that correction.^[ref]

An experimental physicist who coauthored the 2015 Delft electron-spin Bell test. The experiment entangled electron spins at sites separated by 1.3 kilometres. Efficient readout addressed the detection loophole, while fast random measurement choices and the separation addressed the locality loophole. The observed violation of a Bell inequality tested local realism without relying on fair sampling of undetected events.^[ref]

Ben Mottelson helped connect independent-particle nuclear motion with collective excitations. In a simple positive-parity, $K=0$ ground state nuclear rotational band of an even-even nucleus, the excitation energies approximately follow $E_J={\hslash }^{2}J(J+1)/(2\mathcal{I})$ for $J=0,2,4,\dots$, where $\mathcal{I}$ is a moment of inertia. Thus $E_4/E_2=10/3$ in this idealization. Comparing such patterns and transition strengths with observation distinguishes organized collective motion from an arbitrary list of separate particle excitations.^[ref]

A physicist.^[ref]

Beth Parks coauthored a quantum treatment of beam splitters with Charles H. Holbrow and Enrique Galvez. Describing the device requires complex probability amplitudes and their relative quantum phases, not only the fraction of power sent to each output. A unitary matrix transforms the input optical modes into the output modes, connecting single-photon detection probabilities with experiments involving correlated photons. This gives an experimental device a common mathematical description across several quantum-optics demonstrations.^[ref]

A physicist.^[ref]

Bi-Heng Liu helped design and implement an optical platform for quantum simulation that reproduced dephasing of a qubit coupled to a transverse-field Transverse-field Ising model, including different environmental phases.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Science and Technology of China, CAS Key Laboratory of Quantum Information.^[ref]