Qubit fidelity is a general term referring to how accurately a quantum operation (gate, measurement, or state preparation) is performed on a qubit. It is expressed as a number between 0 and 1, where 1 represents a perfect operation.
Why it matters. Fidelity is the umbrella metric that captures the quality of every interaction with a qubit. Gate fidelity measures how well a quantum gate matches its ideal specification. Readout fidelity measures how reliably the qubit state can be determined. State preparation fidelity measures how accurately the qubit is initialized. Each of these fidelities contributes to the overall performance of a quantum computation and determines the overhead required for error correction. Improving qubit fidelity is a joint effort between qubit hardware (better materials, designs, and fabrication) and control systems (lower noise, more precise timing, better calibration).
How it connects. Every aspect of the Qblox control stack is designed to maximize qubit fidelity: low noise and high SFDR for spectral purity, fast rise times for clean pulse edges, sub-nanosecond synchronization for accurate multi-qubit operations, real-time calibration routines for maintaining optimal parameters, and on-board state discrimination for high-fidelity readout. Learn more about the Qblox Cluster.
