Benchmarking engineered exchange interactions on NISQ hardware

Abstract

Abstract Engineered exchange interactions, realized through the i SWAP and $$\sqrt{i\text {SWAP}}$$ gates, play a fundamental role in entangling operations for quantum algorithms, simulation of spin-exchange dynamics, and optimized qubit connectivity. In this work, we present hardware-aware implementations of the i SWAP and $$\sqrt{i\text {SWAP}}$$ gates tailored to superconducting quantum processors, along with comprehensive characterization using both quantum process tomography (QPT) and direct state measurements (DSM). QPT results show process fidelities of 97.32% ( i SWAP) and 98.02% ( $$\sqrt{i\text {SWAP}}$$ ) on quantum simulator, decreasing to 89.72% and 87.65% on quantum hardware, respectively. DSM on the $$|00\rangle$$ input state reveals that the i SWAP implementation achieves higher state preservation fidelity on hardware (93.53% vs. 92.44% for $$\sqrt{i\text {SWAP}}$$ ) but shows higher measured $$|11\rangle$$ population (2.26% vs. 0.38%). These results establish a benchmark for anisotropic exchange gates on noisy intermediate-scale quantum (NISQ) hardware and provide quantitative performance data to inform gate selection for quantum circuit design in the NISQ era.