When dealing with NISQ backends, the presence of “orphan qubits” – qubits with significantly degraded coherence – can contaminate measurement outcomes, impacting the performance of superposition principle circuits designed for tasks like Shor’s algorithm.
Superposition Circuits: The Peril of Orphaned States
The core issue is that orphan qubits don’t just fail; they actively degrade the ensemble measurement. When probability amplitudes are affected by qubits with very short coherence times, the interference pattern collapses. This is especially significant when the contamination ratio reaches approximately 10%.
Principle Circuits: Superposition’s V5 Exclusion
The V5 measurement exclusion strategy offers a systematic approach to mitigate this issue. It identifies and isolates shots where qubits show anomalous statistics, deviating from expected stabilizer structures or marginal distributions. This involves filtering measurement data to exclude or down-weight outcomes from “poison qubits”.
Superposition Principle Circuits: Filtering Poisoned States
By implementing this approach, the impact of “poison qubits” can be filtered out, potentially leading to improved results in Shor-like period finding and ECDLP problems using hardware-optimized techniques (H.O.T. Framework).
Superposition Principle Circuits: Harnessing Noise
The goal is to engineer around the limitations of NISQ hardware, turning the noise into a signal through improved signal extraction. Testing this with a moderate-sized circuit and applying a V5-style exclusion layer will showcase the improvements in signal extraction from noisy shots.
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