Design and Evaluation of Low-Depth Approximate Quantum Computing

초록

Approximate quantum adders are gaining traction in NISQ-era computing for their potential to reduce quantum resource usage while preserving computational accuracy. In this work, we evaluate two 8-qubit hybrid approximate quantum adders that combine a 2-qubit approximate block, either a pass-through Copy Adder or a CNOT-based design, with a 6-qubit Cuccaro ripple-carry adder. Simulations are conducted using IBM's Qiskit framework under realistic noise models, including bit-flip, depolarizing, and thermal noise. Compared to the exact 8-bit Cuccaro adder, our designs reduce quantum cost and circuit depth by over 20 percent and achieve up to 79.3 percent higher output probability under noisy conditions. These results highlight the robustness and efficiency of approximate logic in noisy quantum environments and confirm its practicality for near-term quantum hardware. © 2025 IEEE.

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