Multiphoton antiresonance

We show that nonlinear response of a quantum oscillator displays antiresonant dips as the field frequency passes adiabatically through multiphoton resonance. This coherent quantum effect has no analog in two-level systems. Its emergence is a consequence of special symmetry of a weakly nonlinear oscillator. We discuss the possibility to observe the antiresonance and the associated multiphoton Rabi oscillations in Josephson junctions.