The evolution of a system subject to measurement is restricted to Zeno subspaces of the measurement Hamiltonian in the limit of strong measurements $k$ in a phenomenon known as the quantum Zeno effect (QZE). As the limit constrains QZE to the lowest orders of perturbation in $1/k$, we derive general expressions for the maximum probability leakage from Zeno subspaces for reversible interactions and leakage rates for irreversible interactions for both quantum decay and Lindblad measurement operators. We show that pulsed QZE can be expressed in the same Hamiltonian formulation as continuous QZE, and the two merge in the large-frequency $f$ limit. We derive a nonperturbative expression for pulsed QZE at finite $k$ and $f$, which reduces to previously known results for pulsed QZE at large $k$ and continuous QZE at large $f$.

• Received 22 February 2018

DOI:https://doi.org/10.1103/PhysRevA.98.052132