Phase dependent interference effects on atomic excitation

We present an experimental and theoretical study of phase-dependent interference effects in multi-photon excitation under bichromatic radio-frequency (rf) field. Using an intense rf pulse, we study the interference between the three-photon and one-photon transition between the Zeeman sub-levels of the ground state of 87Rb that allows us to determine the carrier-envelope phase of the fields even for long pulses.

Research Highlights► Observation of carrier-envelope phase(CEP) effects for multi-cycle pulses (up to 15 cycles). ► Provides the insight of CEP effects in a new regime. ► The experiment provides a unique system serving as an experimental model for studying ultrashort optical pulses. ► Determination of the CEP of the fields even for long pulses.