Attosecond quantum control of optical microcavities via unipolar rectangular light pulses

Unipolar light pulses with non-zero electric area enable ultrafast control of quantum systems, requiring tailored temporal shapes like rectangular pulses for efficient atomic manipulation. Such pulses induce unique phenomena, including dynamic microcavities at resonant transitions in multilevel media. Here, we compare microcavity dynamics in two- and three-level media under rectangular unipolar pulse excitation via numerical solutions of the density matrix and wave equations. Unlike Gaussian pulses, rectangular pulses exhibit starkly different dynamics in a three-level medium, disrupting self-induced transparency-like regimes. Key differences emerge when pulses behave as 2 π pulses, highlighting the impact of the third level on microcavity dynamics. These findings establish rectangular unipolar attosecond pulses as a powerful tool for attosecond-scale quantum control, revealing fundamental limits of few-level approximations in extreme nonlinear optics and opening pathways to coherent light–matter engineering in complex atomic systems.