Feed-forward in quantum computing is the process of performing a measurement on one or more qubits during a computation and using the classical result to determine the next quantum operation to be performed, with the decision and execution happening in real time.
Why it matters. Feed-forward is essential for several key quantum computing techniques. In measurement-based quantum computing, the entire computation proceeds through sequential measurements and classically conditioned operations. In quantum error correction, syndrome measurements must be decoded and corrections applied before the next error cycle. Teleportation-based gates, which are important for certain fault-tolerant architectures, require feed-forward to complete the gate. The speed of feed-forward (from measurement to conditional pulse) must be fast enough that the qubits remain coherent throughout the process, imposing strict latency requirements on the control system.How it connects. The Qblox Cluster's LINQ protocol enables feed-forward operations across the full Cluster, with a scalable feedback loop under 650 nanoseconds. Measurement results from any readout module are processed on-board (including state discrimination) and routed to any control module for conditional pulse playback.
