On-Demand Quantum Coherence Enhancement via Active Neighbor Interface Driving in Superconducting Qubit Arrays: Experimental Evidence and Theoretical Framework
T. M. Nguyen
On-Demand Quantum Coherence Enhancement via Active Neighbor Interface Driving in Superconducting Qubit Arrays: Experimental Evidence and Theoretical Framework This deposit contains the complete experimental record for the first reported observation of the bait-unit effect — a coherence enhancement mechanism predicted by Self-Field Theory (SFT) in which active neighboring qubits redirect local observer coupling away from a target qubit, extending its T2 coherence time. The effect is directionally opposite to what standard crosstalk models predict. Experimental results: ACTIVE > CONTROL in 29/32 clean repetitions across three independent IBM quantum processors (ibm_fez Heron R2, ibm_torino Heron R1, ibm_marrakesh). Active T2 values exceeded each chip's hardware maximum on all three architectures. A convergence band near 490-503 µs emerged consistently across all three processors with 24 bait qubits. An A-B-A design confirmed the effect is tied to bait configuration rather than qubit state drift. Contents:- Full paper with methods, results, limitations, and discussion- Experimental script (sft_minimal_test_final.py) for independent replication- How-to guide for IBM Quantum free-tier users- Troubleshooting guide covering all documented failure modes- Two separate plotter programs (envelope and AUC) to obtain directional results Theoretical framework: Self-Field Theory (SFT) proposes that quantum measurement involves a finite population of stable topological observers — Selflitons — that couple to coherent interfaces following a thermodynamic gradient. The bait-unit effect was a specific falsifiable prediction of this framework made prior to experimental design. Standard crosstalk models predict the opposite result. Replication: The experimental script runs on a free IBM Quantum account. All data including failed runs is provided. No results were selectively excluded. Honest assessment of prior observations: Early experimental runs (prior to March 2026) indicated a much larger enhancement, in some cases exceeding 25%. Subsequent investigation identified that these large values were primarily due to fitter artifacts caused by an insufficient Ramsey delay window relative to the native T2 of the target qubits. When the delay window is too short to capture the full exponential decay, the exponential fitter returns artificially inflated T2 values across all conditions (IDLE, CONTROL, and ACTIVE). However, because ACTIVE consistently decayed slower than IDLE and CONTROL, the directional signal (ACTIVE > CONTROL) was always present; the magnitude was not. With the introduction of the automated calibration phase, which dynamically adjusts the delay window to be 3-5 times the IBM-calibrated T2 for each target qubit, the fitter saturation artifacts were largely eliminated. Under these cleaner measurement conditions, the observed enhancement consistently fell to the 1-2% range. This revision is not a retraction of the effect but a refinement of its measured magnitude. The directional prediction (ACTIVE > CONTROL) remains confirmed at 91% consistency across decisive runs. The magnitude now aligns quantitatively with the SFT prediction that includes the spatial kernel K(r) derived from the hedgehog profile, with ζ ≈ 0.100 and ΣK(r_j) ≈ 0.15 for typical chip layouts, yielding a predicted enhancement of approximately 1.5%. The earlier, larger values were a measurement artifact; the underlying physical effect is smaller than initially thought, but also exactly where the theory said it would be.
•Mar 22, 2026•0 citations