Periodic Driving Enhances Quantum Zeno Protection of a Superconducting Qubit

Abstract

The quantum Zeno effect, in which frequent measurements suppress the evolution of a quantum system, is well characterized for static Hamiltonians. We investigate how periodic driving modifies Zeno protection for a single qubit on the superconducting processor ibm_marrakesh. In our gate‐based protocol, an interrupted Rabi oscillation is combined with a digitized longitudinal drive of frequency Ω$\Omega$ and amplitude A$A$ , and the number of projective measurements, N$N$ , is varied. Strong driving ( Ω=6$\Omega = 6$ , A=1.5$A = 1.5$ , dimensionless circuit units) enhances peak survival at the optimal measurement number N∗=8$N^* = 8$ by approximately 21%$21\%$ relative to the undriven case, and reduces the effective per‐interval decay rate by up to 51%$51\%$ . The relative enhancement was reproduced across two sessions separated by a recalibration cycle ( 21.0%$21.0\%$ and 21.3%$21.3\%$ , consistent within the ∼2%${\sim }2\%$ statistical uncertainty), while absolute survival shifted by about 18 percentage points, identifying the relative enhancement as the robust quantity. Exact noiseless predictions computed from the Trotterized circuit unitaries track the hardware data with a consistent decoherence offset. A Trotter‐step control experiment shows that an apparent single‐measurement survival anomaly under fast driving ( Ω=12$\Omega = 12$ ) is a discretization artifact, illustrating the need for convergence verification when digitizing periodic drives.