What is the name of the wavelength associated with a moving particle in quantum mechanics?

The wavelength associated with a moving particle in quantum mechanics is called the de Broglie wavelength.

Louis de Broglie proposed the idea in 1924, extending wave-particle duality from light to matter. He suggested that a particle with momentum p has a wavelength λ given by λ = h/p, where h is the Planck constant. Faster or more massive particles generally have greater momentum and therefore shorter de Broglie wavelengths.

The idea made electrons more than tiny classical particles: they could also produce interference and diffraction. Electron-diffraction experiments by Clinton Davisson and Lester Germer, and independently by George Paget Thomson, confirmed this wave-like behavior in 1927. De Broglie received the 1929 Nobel Prize in Physics for the discovery of the wave nature of electrons.

The term is sometimes confused with the Compton wavelength. The Compton wavelength is tied to a particle's mass and scattering processes, while the de Broglie wavelength depends on momentum and describes the wave associated with motion. Matter waves are now central to electron microscopy, neutron diffraction, and atom interferometry.