Measurement-count–dependent phase shift induced by mid-circuit measurements in dynamic superconducting quantum circuits: a Ramsey diagnostic on IBM Quantum hardware

This record provides a manuscript and a reproducibility bundle reporting an effective, measurement-count–dependent phase shift observed in dynamic quantum circuits on IBM Quantum superconducting hardware (backend: ibm_marrakesh). Using a Ramsey-type phase estimation on a target qubit with repeated mid-circuit measurements (M) applied to a spectator qubit, we compute the phase θ from XY tomography (θ = atan2(Y, X)) and the contrast r = sqrt(X^2 + Y^2). A delay-matched control is used to remove baseline drift, and we define the effective signal Δθ_eff(M) = [θ_MEAS(M) − θ_MEAS(0)] − [θ_DELAY(M) − θ_DELAY(0)]. For T = 40 μs and 4096 shots, we observe a clear monotonic negative drift with M (M = 0,1,2,4,8), with a typical statistical uncertainty of ~0.03 rad and high contrast r ~ 0.84–0.91. The bundle includes raw run logs, processed CSV tables, figures, and an analysis script, enabling independent reanalysis. The results are directly relevant to calibration and mitigation of dynamic circuits where mid-circuit measurement operations can introduce coherent phase errors. Keywords quantum computing; dynamic circuits; mid-circuit measurement; Ramsey interferometry; phase shift; measurement-induced dephasing; crosstalk; superconducting qubits; IBM Quantum Notes / Acknowledgements We acknowledge the use of IBM Quantum services for this work. The views expressed are those of the author and do not reflect the official policy or position of IBM or the IBM Quantum team.