The maser - new type of microwave amplifier, frequency standard, and spectrometer.

In 1964 Townes shared the Nobel Prize in Physics with Nicolay Gennadiyevich Basov and Alexandr Mihailovich Prokhorov "for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle."

Order of authorship in the original publication: Gordon, Zeiger, Townes.