Experiments

Discovery

  1. Blackbody radiation Otto Lummer; Ernst Pringsheim (1890s-1900) Experimental spectrum contradicted classical physics; motivated Planck’s energy quantization

  2. Photoelectric effect Philipp Lenard; Albert Einstein (1902-1905) Electron emission depends on frequency, not intensity; evidence for light quanta

  3. Atomic emission spectra Johann Balmer; Johannes Rydberg (1885-1890s) Discrete spectral lines implied quantized atomic energy levels

  4. Franck-Hertz experiment James Franck; Gustav Hertz (1914) Direct experimental confirmation of discrete atomic energy states


Wave–particle duality confirmed

  1. Compton scattering Arthur Compton (1923) Photon momentum and wavelength shift confirmed particle nature of light

  2. Electron diffraction Clinton Davisson; Lester Germer; G. P. Thomson (1927) Matter-wave interference verified de Broglie’s hypothesis


Foundations of quantum mechanics tested

  1. Stern-Gerlach experiment Otto Stern; Walther Gerlach (1922) Spatial quantization and intrinsic spin revealed; classical angular momentum ruled out

  2. Single-particle interference Jönsson; Tonomura et al. (1960s-1980s) Individual particles form interference patterns; wavefunction describes probabilities, not ensembles


Quantum electrodynamics & precision tests

  1. Lamb shift Willis Lamb; Robert Retherford (1947) Small hydrogen energy shifts required QED corrections and renormalization

  2. Anomalous magnetic moment of the electron Multiple authors (1947-present) Agreement between theory and experiment to parts per trillion; benchmark of QED accuracy


Entanglement and nonlocality

  1. Bell inequalities John Bell (1964) Provided experimentally testable distinction between quantum mechanics and local hidden-variable theories

  2. Bell test experiments Alain Aspect et al. (1982) Violation of Bell inequalities confirmed quantum nonlocal correlations


Many-body & condensed matter breakthroughs

  1. Integer quantum Hall effect Klaus von Klitzing (1980) Exact quantization revealed topological invariants in quantum systems

  2. Fractional quantum Hall effect Tsui; Stormer; Laughlin (1982-1983) Emergence of quasiparticles with fractional charge and statistics


Modern quantum experiments

  1. Bose-Einstein condensation Eric Cornell; Carl Wieman; Wolfgang Ketterle (1995) Macroscopic occupation of a single quantum state directly observed

  2. Quantum teleportation Dik Bouwmeester et al. (1997) Quantum state transfer enabled by entanglement and classical communication

  3. Loophole-free Bell tests Ronald Hanson; Bas Hensen et al. (2015) Closure of detection and locality loopholes; definitive nonlocality tests

  4. Quantum computational advantage Google Quantum AI (2019) Task-specific demonstration of quantum speedup over classical computation


Quantum gravity-adjacent observations

  1. Hawking radiation Stephen Hawking (1974, theoretical) Quantum particle production predicted in curved spacetime; no direct astrophysical detection yet