Norman Ramsey Jr. developed precision magnetic resonance using separated oscillatory fields. A particle encounters two short coherent interactions with an interval of free evolution between them. The first interaction prepares a quantum superposition; the second converts the accumulated relative quantum phase into a measurable population difference. A small frequency mismatch accumulates quantum phase during the free interval, producing narrow interference fringes whose scale depends on that interval. Ramsey interferometry turns controlled coherent evolution into a precise frequency comparison.[ref]
A Molecular Beam Resonance Method with Separated Oscillating Fields by Norman Foster Ramsey, Jr.. 1950 method: separated interaction regions and narrow resonance structure
Identity source: news.harvard.edu/gazette/story/2015/07/norman-foster-ramsey-jr/
Portrait of Norman Ramsey Jr.
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Norman Ramsey Jr. was an American physicist known for his significant contributions to the field of atomic physics and quantum mechanics. Born on August 27, 1915, he won the Nobel Prize in Physics in 1989 for his work on the development of methods for the precise measurement of molecular beams and for pioneering techniques in atomic clocks. Ramsey's work has had a profound impact on the fields of metrology and the development of technologies such as GPS, which rely on precise timing measurements.