What is measured when a qubit measurement is performed on a multi-qubit chip?

Abstract

We study how single-qubit dispersive readout works alongside two qubit coupling. To make calculations analytically tractable, we use a simplified model which retains core characteristics of but is discretised compared to dispersive homodyne detection. We show how measurement speed and power determine what information about the qubit(s) is accessed. Specifically we find the basis the measurement is closest to projecting onto. Compared to the basis gates are applied in, this measurement basis is modified by the presence of photons in the readout resonator.

4 figures, v2: added some discussion, close to published version

References in corpus (3)

• Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement
• The information about the state of a qubit gained by a weakly coupled detector
• Weak and strong measurement of a qubit using a switching-based detector

Cited by in corpus (4)

• Transmon platform for quantum computing challenged by chaotic fluctuations
• A randomized benchmarking suite for mid-circuit measurements
• SuperGrad: a differentiable simulator for superconducting processors
• Exploring the Fidelity of Flux Qubit Measurement in Different Bases via the Quantum Flux Parametron