Abstract
We propose a concept of fractional quantum resonances based on an idea of driving a quantum system by an external field in the form of a repetitive pulse sequence. We show that, in addition to intuitively expected resonance at repetition rate equal to the internal quantum frequency , the system exhibits less intuitive fractional quantum resonances at , with being an integer. It is a nonintuitive phenomenon since the external repetition rate has no quantum character, yet the atom responds to it, if the rate is equal to of its eigenfrequency. This result is in good agreement with recent magnetometer experiments. It is also found that other resonances are possible at pulse-repetition-rate frequencies equal to of combination frequencies involving the internal system frequencies and Rabi frequencies. We show that quantum-interference-related phenomena of gain without population inversion and absorption with inversion are observed at these unique resonances. Fractional quantum resonances provide a spectroscopy tool, allowing us to measure optical frequency on one transition through detection of resonances on another transition. We believe that our results will have implications in other quantum-related processes, such as laser-assisted resonant enhancement of chemical reactions and biological processes.
- Received 19 September 2014
DOI:https://doi.org/10.1103/PhysRevA.91.023819
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