Ramseyinterferometria

Ramseyinterferometria, also known as Ramsey interferometry, is a technique in quantum physics used for precision measurement of transition frequencies and coherence properties of quantum systems. It employs two short, coherent pulses separated by a period of free evolution. The method is widely applied to atomic, ionic, and other two-level systems to read out phase information accumulated during the evolution period.

In the standard Ramsey sequence, the first pulse creates a coherent superposition of the two levels (a π/2 pulse). During the subsequent free evolution time T, the relative phase between the levels accumulates at a rate determined by the detuning between the driving field and the transition frequency. The second π/2 pulse converts this accumulated phase into a population difference that can be measured. The resulting signal shows interference fringes as a function of detuning or the interrogation time. The probability of finding the system in the excited state is typically written as P_e = (1/2)[1 + V cos(δ T + φ)], where δ is the detuning, T is the free evolution time, V is the fringe visibility, and φ is a phase offset.

Ramsey interferometry offers high spectral resolution because the fringe spacing scales inversely with T, allowing very narrow resonances with relatively modest field amplitudes. It is robust against certain technical noise and allows precise determination of transition frequencies, coherence times, and systematic shifts.

Applications include precision atomic and molecular spectroscopy, development and operation of optical and microwave atomic clocks (in atoms like cesium, rubidium, strontium, and ytterbium), trapped-ion and neutral-atom quantum sensors, and fundamental studies of coherence and interactions in quantum systems. The technique is a cornerstone of modern quantum metrology.