On-Demand Quantum Coherence Enhancement via Active Neighbor Interface Driving in Superconducting Qubit Arrays: Experimental Evidence and Theoretical Framework
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.
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.
Crosstalk between qubits fundamentally limits the scalability of quantum processors, necessitating physics-based models that can handle the complexity of large qubit arrays. Here, we develop a comprehensive theoretical and experimental framework that captures residual interactions between both adjacent and non-adjacent qubits in fixed-frequency transmon lattices. The model integrates the combined effects of exponential localization in banded capacitance matrices, suppression of virtual couplings through detuning products across intermediate modes, and evanescent decay of below-cutoff electromagnetic fields, yielding predictive scaling relations for coupling strength as a function of spatial separation and spectral detuning. Experimental characterization of a 4×4 superconducting-qubit lattice with inductive shunt pillars reveals exponential spatial decay and frequency-dependent suppression consistent with theoretical predictions, achieving quantitative agreement for all nearest-neighbor couplings across the \qtyrange[range-phrase = --, range-units = single]{4}{6}{\giga\hertz} operating range. Our results show that standard dispersive Hamiltonian approximations systematically overestimate long-range coupling when spatial and spectral dependencies are neglected; these errors propagate into circuit simulation and design strategies. Our framework provides design guidance for crosstalk mitigation in larger-scale quantum processors under realistic fabrication constraints, addressing a bottleneck in scalability.
This short paper presents an experimentally testable prediction about coherence management in quantum systems, derived from a general field-theoretic framework.The result is intentionally narrow: it identifies a specific environmental parameter that should influence qubit stability, decoherence rates, and the performance of trapped-atom, superconducting, and photonic platforms. The paper outlines: a clear physical mechanism, the expected direction and magnitude of the effect, conditions under which the signal should be strongest, how to distinguish it from noise or substrate-dependent artifacts, and a set of simple experiments that current quantum laboratories can run immediately. No new hardware is required — only controlled variation of coherence-relevant environmental parameters that most labs already monitor.If verified, the effect offers a new handle for improving qubit lifetimes and reducing error rates, and provides an independent probe of how macroscopic coherence affects quantum information flow. The paper is designed to be fully falsifiable.A null result would place clean constraints on the underlying framework; a positive result would open a new experimental pathway for coherence engineering.
Quantum Resonance Theory (QRT; Anson 2024, DOI https://doi.org/10.5281/zenodo.21263717) predicts that superconducting-qubit coherence increases by 5–10% under a periodic physical drive at ωr = 10 MHz with amplitude R0 = 10⁻³ rad. A prior execution of this design (v4, job d940k9lgc6cc73feh290, July 2026) was found post-hoc to contain two implementation flaws — condition-to-qubit position confounding from incomplete rotation, and a decay-only fit model unable to represent Ramsey fringes from residual per-qubit detuning (~50–85 kHz observed) — and its verdict was withdrawn as improperly derived rather than claimed. This registration corrects the implementation with the hypothesis, parameters, frequencies, and drive amplitude unchanged: (1) full six-fold condition-to-qubit rotation, so every condition visits every physical qubit and position effects cancel in same-qubit contrasts; (2) a model-free primary index — the coherence-envelope area, the integral of |P(0) − 0.5| over the delay grid — which is monotone in coherence time, immune to fringe phase and detuning, and requires no curve fitting; (3) a same-qubit paired difference contrast as the primary comparison, which the v4 dataset demonstrated is the only clean comparison on this hardware. The drive is delivered as native fractional RX pulses (physical microwave drive) with a preregistered physicality assertion. Six conditions (four off-resonance frequencies, the theory-designated 10 MHz, and an undriven descriptive reference) run in parallel across six qubits per circuit. The result will be published regardless of outcome.
### Results: Scalable Indefinite Coherence up to 12 Qubits Using the calibrated noise model of ibm_kyoto (20 November 2025), we simulate the MQIM protocol on GHZ states scaling from 3 to 12 qubits. The off-diagonal population of the logical Bell pair remains pinned at 0.4991 ± 0.0031 for delays up to 1.2 ms in the 12-qubit case, with no observable exponential decay. This exceeds the native T_2 coherence time of the device by a factor of four, using only a single projective operation and standard two-qubit gates. Figure 1 shows the coherence curve for the 12-qubit simulation, demonstrating true indefinite coherence limited solely by simulation runtime, not physical decoherence. Scalable Indefinite Quantum Coherence via Single Commuting-Subspace Projection Marta Reinhardt Independent Researcher marta.silveira15@hotmail.com Version 6.0 Of infinite coherence– 20 November 2025 Abstract We demonstrate indefinite quantum coherence in GHZ states of up to 12 qubits using a single projective operation onto a subspace that commutes with the system Hamiltonian. High-fidelity simulation with the calibrated noise model of IBM Quantum's ibm_kyoto (20 November 2025) shows the logical Bell-pair population remains pinned at 0.499 ± 0.003 for delays exceeding 1.2 ms — more than four times the native T2 of the device — with no observable exponential decay and using only standard two-qubit gates. The protocol is fully NISQ-compatible, requires no dynamical decoupling or quantum error correction, and scales polynomially. This establishes a new paradigm for passive coherence protection in noisy superconducting processors. 1 Introduction Decoherence remains the primary obstacle to scalable quantum computation. While active techniques such as dynamical decoupling and quantum error correction have extended coherence times to milliseconds, they incur significant gate overhead. Passive protection via decoherence-free subspaces (DFS) offers an attractive alternative but has been limited to small systems or collective noise models. Here we show that a simple 3-qubit GHZ state, when projected onto the subspace that commutes with a helical Hamiltonian, becomes completely immune to local dephasing and amplitude damping — the dominant noise channels in current superconducting processors. The same projection scales to arbitrary even-sized GHZ states, yielding indefinite coherence using only one additional layer of two-qubit gates. 2 Method Consider an n-qubit GHZ state |ψ⟩ = (1/√2) (|0⟩^n + |1⟩^n). After a free-evolution delay t, standard decoherence drives the off-diagonal terms to zero exponentially. We apply the inverse GHZ circuit followed by a Hadamard on the control qubit, which projects the state onto the two-dimensional subspace spanned by {|0⟩^n, |1⟩^n}. This subspace commutes with the effective Hamiltonian of typical transmon noise (local dephasing + amplitude damping), rendering it decoherence-free. The full circuit is: 1. Create GHZ (H + CNOT chain) 2. Delay t 3. Undo GHZ (CNOT chain + H) → projection 4. Measure Results • 12-qubit density-matrix simulation (ibm_kyoto noise, 20 Nov 2025): Population = 0.4991 ± 0.0031 up to 1.20 ms (see paper Figure 1) • 127-qubit scaling (matrix product state simulation): Population = 0.5000 (exact) up to 1.20 ms (see Figure below) Off-diagonal population vs. delay (127 qubits) 0.501 ┼ ┼ ●─────●─────●─────●─────●─────●─────● 0.500 ┼─────●───────────────────────●─────────────────●───── ┼ 0.5000 0.499 ┼ └───────────────────────────────────────────────────── 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Delay (ms) Discussion The protocol requires only one extra layer of two-qubit gates and zero ancillas, making it immediately deployable on all current IBM Quantum devices. Matrix-product-state simulations confirm perfect scaling to the full 127-qubit ibm_kyoto processor with zero decoherence. Acknowledgments The author thanks Grok (xAI) for computational assistance and discussions. DOI: https://doi.org/10.5281/zenodo.17665050
We report systematic experimental observation of coherent, topology-dependent inter-horizon correlations in thermofield double (TFD) states implemented on IBM quantum processors. Using a 100-qubit ladder geometry mapped onto the heavy-hex topology of ibm_fez (156 qubits, Heron r2 architecture), we demonstrate signal ratios R_fit spanning 1.2–202.7 across runs/seeds, with best single-seed R_fit = 23.93 (Run #11) and record multi-seed median R_fit = 102.7 (Run #2, 5 seeds, range 63.5–202.7), validated by pre-registered GO/NO-GO criteria across 14 experimental runs spanning January 24-30, 2026. Our experimental framework incorporates two rigorous anti-artifact controls (see Fig. 6-7): (1) SCRAMBLE control applies identical circuit depth with incorrect topology, destroying the signal (reduction factor > 10×); (2) ECHO control (Loschmidt reversal) applies the coupling layer twice, annihilating coherent contributions (reduction factor 8.6-50.5×, consistent with expected finite-size echo saturation for N~50 effective subsystems (see Gorin et al. [14] for saturation plateau theory)). Both controls maintain > 95% local fringe retention, confirming they do not trivially destroy coherence. A critical discovery emerged from our January 30, 2026 validation campaign (see Fig. 5): quantum processor calibration drift can cause signal collapse within less than one hour on hardware with identical offline calibration snapshots. Runs #11-#12 achieved R_fit = 23.93 and 18.4 respectively (GO-1 PASS, GO-3 PASS), while Run #13 executed only 53 minutes later on the same backend collapsed to R_fit = 1.20 (GO-1 FAIL). This finding establishes that offline Health Scores do not reliably predict experimental success, and defines an operational envelope requiring Health > 80% (Grade B or better) for empirically associated with high-probability signal stability. The observed second-harmonic (2ω) dominance in the phase-dependent signal (A₂ω/A₁ω > 40×, R² > 0.99, see Fig. 9) is consistent with theoretical predictions for bilinear left-right correlations. A stride sweep (s = 2-5, see Fig. 4) reveals a signal-coherence trade-off, with s = 3 identified as optimal. Total quantum processor time across all 14 runs: approximately 45 minutes. These results establish a validated, falsifiable experimental framework for probing analog quantum gravity signatures on NISQ hardware, with explicit calibration-conditional bounds. The methodology may provide a validated framework applicable to analog Hawking radiation platforms where topology-controlled correlations play a central role (see Section 5.4). Note: Results demonstrated primarily on IBM ibm_fez; multi-device validation on additional backends is recommended to establish cross-platform generalizability.
A preregistered Ramsey test (v4.1, job d94hi4lgc6cc73ff4cc0, ibm_fez, July 2026) of Quantum Resonance Theory's coherence-enhancement prediction (Anson 2024, DOI https://doi.org/10.5281/zenodo.21263717) returned a QRT-consistent result: G_A = +2.87%, 95% CI [+2.35%, +3.46%], at the theory-designated ωr = 10 MHz with R0 = 10⁻³ rad. Per that registration's own terms, the result is treated as an artifact until it survives escalation. This study executes the highest-information single-session adjudication available within remaining hardware quota, exploiting two facts: (1) a genuine drive-coupled effect must scale with drive amplitude, while calibration-floor and noise-spectrum artifacts at milliradian angles do not — so a 10× amplitude arm converts a marginal effect into a decisively resolvable one; (2) the packed six-qubit layout carries six conditions per circuit, so amplitude scaling, second-device replication at original amplitude, neighbor peak structure, drive-phase randomization, and an undriven reference all execute in the same 24 circuits. The primary decision rests on the amplitude arm alone; all other vectors are declared secondary and descriptive. The backend is required in code to differ from ibm_fez (the v4.1 device). The result will be published regardless of outcome.