
Adaptive Quantum Circuits
AQC26 Recorded Talks
Dr. David Stephen
A universal framework for adaptive quantum circuits
Abstract
An inherent feature of quantum computation is the ability to trade between temporal resources, i.e. circuit time or shot count, and spatial resources, i.e. qubit number. In particular, quantum circuits can be accelerated when more qubits are available. Typically, this comes from the use of quantum error correction codes that are less space-efficient but more time-efficient. Here, we propose a general method that makes space-time tradeoffs directly on the level of logical circuits, agnostic to any lower-level error correction scheme. We derive a recipe to augment any logical circuit with ancilla qubits, mid-circuit measurements, and classical feedforward, resulting in a logically-equivalent adaptive circuit. Using M ancilla qubits, we achieve circuit depth that scales as 1/M while maintaining low gate counts. We benchmark our approach on Quantinuum’s Helios 98-qubit trapped-ion quantum processor, observing increased circuit fidelity alongside decreased runtime. By combining our approach with circuit compression methods, we use Helios to sample from a large 500-qubit circuit with 100 T gates with high-estimated fidelity. Overall, our method provides a unified and flexible approach to adaptive circuit construction that can be tailored to arbitrary physical and fault-tolerant architectures.