Quantifying State Transitions in Superconducting Qubit Mid-Circuit Measurements Using Quantum Instrument Linear Gate Set Tomography

High-performance mid-circuit and terminal measurements are essential for a wide range of quantum computing applications and error correction schemes. Accurate characterization is crucial for understanding measurement errors and building accurate predictive models of multi-qubit systems and quantum error correction primitives. In this talk we discuss recent tomographic techniques for thorough characterization of measurements on a superconducting quantum processor. In particular, we use quantum instrument linear gate set tomography (QILGST) to detect measurement-induced state transitions (MIST). We use this analysis to understand how leakage outside of the computational subspace can corrupt estimates of transition rates within the computational subspace, and we explore how expanded models can mitigate this effect.