Optimizing multi-qubit readout for mid-circuit measurements and low latency feedback based applications

Multi-qubit readout fidelity is extremely important both for NISQ era quantum machines as well as towards developing fault tolerant error corrected quantum computers. Optimizing multi-qubit readout fidelity in quantum processors based on superconducting qubits is a challenging task as typically many readout resonators must be probed simultaneously via frequency multiplexing and the crosstalk effects should be considered. Moreover, in some applications, it is desirable to apply low latency feedback-based operations on qubits, which depend on the results of mid-circuit, multi-qubit readout, e.g. in quantum error correction. In such applications, reducing the readout duration and the state estimation classical processing are critical. Here we propose a novel approach for multi-qubit readout where a multi-tone signal is processed in real-time to achieve low latency multi-qubit readout, while optimizing for cross talk considerations. Moreover, we demonstrate how QM's flexible control platform, the Quantum Orchestration Platform, allows to explore such multi-tone signal processing from easy-to-use SW interface.