He developed the Bohr model of the atom, introduced the concept of complementarity, and founded the Copenhagen interpretation of quantum mechanics.
He proposed the photon theory of light, explained the photoelectric effect, stimulated the development of quantum statistics, and contributed to the development of quantum field theory.
He formulated the Schrödinger equation, which describes the wave function of a quantum system, and introduced the concept of wave-particle duality.
He developed the matrix formulation of quantum mechanics, discovered the uncertainty principle, and pioneered the development of quantum mechanics as a consistent logical framework.
He proposed the concept of quanta, or discrete units of energy, and derived the Planck's law of black-body radiation, which initiated the quantum revolution.