Standard Random Circuit Sampling (RCS) predicts full thermalization at sufficient depth, with output distributions converging rapidly toward uniform noise under realistic hardware conditions. Yet several recent experimental results have displayed unexpected persistence of structured output distributions far beyond the expected decoherence horizon. This paper presents a vendor-agnostic benchmark demonstrating that such persistence is not an architectural anomaly, but a direct signature of a deep Rc coherence well as defined in Relational Field Theory (RFT). Rc wells arise when curvature-stiffened regions of the universal scalar field resist chaotic dispersion, enabling stable probability attractors even in circuits where standard quantum dynamics predict complete entropy saturation. We provide a minimal, architecture-independent circuit that any quantum hardware vendor can execute to detect Rc well behavior. The benchmark uses symmetric entanglers, global phase rotation, chaotic scrambling, and convergence layers to probe curvature-stiffened regimes. Four measurable signatures—XEB decay behavior, entropy suppression, HOG persistence, and inverse participation ratio (IPR)—constitute a clear, falsifiable Rc-well fingerprint. This work generalizes beyond any specific architecture and requires no specialized routing, collapse engineering, or deterministic control systems. It offers the first universal test for detecting Rc-governed coherence persistence and forms a reproducible foundation for cross-vendor validation of RFT predictions
Standard Random Circuit Sampling (RCS) predicts full thermalization at sufficient depth, with output distributions converging rapidly toward uniform noise under realistic hardware conditions. Yet several recent experimental results have displayed unexpected persistence of structured output distributions far beyond the expected decoherence horizon. This paper presents a vendor-agnostic benchmark demonstrating that such persistence is not an architectural anomaly, but a direct signature of a deep Rc coherence well as defined in Relational Field Theory (RFT). Rc wells arise when curvature-stiffened regions of the universal scalar field resist chaotic dispersion, enabling stable probability attractors even in circuits where standard quantum dynamics predict complete entropy saturation. We provide a minimal, architecture-independent circuit that any quantum hardware vendor can execute to detect Rc well behavior. The benchmark uses symmetric entanglers, global phase rotation, chaotic scrambling, and convergence layers to probe curvature-stiffened regimes. Four measurable signatures—XEB decay behavior, entropy suppression, HOG persistence, and inverse participation ratio (IPR)—constitute a clear, falsifiable Rc-well fingerprint. This work generalizes beyond any specific architecture and requires no specialized routing, collapse engineering, or deterministic control systems. It offers the first universal test for detecting Rc-governed coherence persistence and forms a reproducible foundation for cross-vendor validation of RFT predictions
This note presents an RFT interpretation of an anomalous coherence persistence effect reported publicly in 2025 RCS benchmark data. Standard quantum-circuit expectations predict full thermalisation on noisy 16-qubit superconducting hardware by depth ~30, driving XEB toward zero and eliminating internal structure. Instead, the publicly reported metrics indicated XEB > 4, HOG > 0.8, and a measurable entropy deficit, revealing structured attractors in a regime where standard models predict complete chaotic dispersion. Relational Field Theory (RFT) provides a natural theoretical explanation for this behavior: the reported anomaly matches the expected signatures of a system entering a deep curvature-stiffened coherence well in the universal scalar field 𝑅 𝑐 R c , allowing attractor structure and causal memory to persist far beyond the expected decoherence horizon. This analysis presents a minimal RFT interpretation based solely on publicly released benchmark metrics. Note: This analysis uses only publicly released circuit metrics. It makes no claims about proprietary architectures, internal mechanisms, trade secrets, or patented methods. No inference is made about the mechanisms or design intentions of QSCE or any other proprietary system.
This paper presents the application of Relational Field Theory (RFT) to random circuit sampling (RCS), a standard benchmark in quantum computing. Building on the reduced relational law: {\dot{R}}_c=-\lambda R_c+F_{int},\bigm and the operational coherence functional: R_c=\alpha\cdot\beta\cdot\gamma,\bigm the framework is applied to reported RCS data from superconducting qubit experiments. Within this setting: α corresponds to distribution sharpness (e.g., cross-entropy benchmark or peak statistics) β reflects circuit connectivity and gate structure γ captures persistence across circuit depth and repeated runs Using published results, the relational coherence functional is evaluated against observed behaviors in RCS systems, including: Persistence of structured output distributions beyond expected circuit depth Formation of coherence wells, where structure remains stable under noise Attractor-like clustering of high-probability output states Suppression of entropy relative to fully randomized expectations These observations are consistent with the four falsifiable predictions introduced in RFT v2.0: critical slowing near coherence thresholds hysteresis-like behavior under parameter variation persistence in coherence wells emergence of structural anchors This work does not modify quantum mechanics or attempt to reproduce standard RCS results. Instead, it provides a structural interpretation of observed behavior using a coherence-based framework applied to existing experimental data. The results extend Relational Field Theory from classical and toy-model systems into the quantum domain, supporting its potential as a cross-domain framework for understanding persistence, structure, and transition dynamics.
Madmartigan RCS Benchmark Update: TRL-7 Real-Backend Validation of QSCE on ibm_marrakesh This technical update presents the first real-hardware Random-Circuit-Sampling (RCS) benchmark of the Quantum State Command Encoding (QSCE) architecture using the 16-qubit, ~55-layer hybrid circuit termed Madmartigan. The experiment was executed directly on the IBM ibm_marrakesh superconducting backend in a TRL-7 configuration with 4096 shots, using the same circuit instance previously validated on the Marrakesh noise model. Despite the adversarial nature of RCS—designed to overwhelm coherence, erase structure, and drive quantum systems into thermalized noise—the Madmartigan benchmark again demonstrates that QSCE maintains strong architectural structure under deep scrambling. On real hardware, the experiment achieves: XEB fidelity: 1.82 (absolute) Heavy-Output Generation (HOG): 0.719 Inverse Participation Ratio (IPR): 3647.22 Normalized IPR (nIPR): 0.0557 Shannon entropy: 11.88 bits (0.7427 normalized) These results extend the prior TRL-6 noise-model findings into a full TRL-7 regime, confirming that the observed behavior is not a simulator artifact. The entropy and IPR windows remain tightly aligned with the noise-model run, while the hardware XEB stays strictly positive at 55 layers—indicating a high-information, non-ergodic attractor band rather than a fully thermalized, Porter–Thomas distribution. As in the simulator study, the goal is not classical intractability but architectural validation: demonstrating that QSCE’s command-collapse logic, deterministic routing, and phase-anchored propagation remain stable even when subjected to deep random unitaries and adversarial entangling layers on real metal. The Madmartigan hardware benchmark therefore provides direct empirical support for QSCE’s orchestration and activation-propagation formalisms, confirming that the architecture exhibits resilience, directional structure, and engineered collapse behavior under one of the most chaotic quantum benchmarking regimes known—now validated at TRL-7 on an IBM production backend.
Random circuit sampling (RCS) on noisy quantum hardware is widely modeled as exhibiting exponential decay of fidelity metrics (e.g., XEB, HOG) with circuit depth, converging toward Haar-random statistics beyond a characteristic noise-limited scale. This work introduces a minimal phenomenological recurrence for a coarse-grained local coherence observable defined on the qubit connectivity graph. The recurrence reproduces standard exponential decay in unstructured (fully scrambled) circuits but predicts delayed thermalization and a nonzero plateau when repeated local motifs are engineered into circuit compilation. The model introduces a single topology-dependent memory parameter α(µ), where µ denotes motif density. A transcritical bifurcation occurs when α(µ) exceeds the effective per-layer decoherence rate γ, producing a calculable plateau height and build-up depth scale. A matched-pair experimental protocol—holding qubit count, two-qubit gate count per layer, and reported hardware error rates fixed while varying only motif density—provides a direct falsification criterion. Absence of statistically significant topology dependence would rule out the model in its minimal form. The recurrence is an effective coarse-grained description at the metric level and does not modify underlying quantum channel structure or violate complete positivity.
We report forward random-circuit sampling (RCS) on the 120-qubit Nighthawk r2 superconducting processor (ibm_phoenix) with square-lattice connectivity, using 61 qubits, native CZ gates, and the standard cloud execution stack with no benchmark-specific calibration. Two independent fidelity estimators---mirror benchmarking and three- and four-patch cross-entropy benchmarking (XEB)---agree with each other at every measured depth, the mirror from 4 to 40 cycles and the patched estimators from 20 to 40 cycles, across more than two orders of magnitude of fidelity decay, and exceed the first-generation Nighthawk r1 device by more than an order of magnitude at fixed depth. The 36-cycle circuits sit at the depth where tensor-network contraction cost saturates at system size: a contraction-cost estimator validated against the published Sycamore and Zuchongzhi networks places the single-amplitude cost at ∼1022 complex operations. At FXEB(36)=2.3×10−3 under favorable memory assumptions this implies 1.2×1027 machine operations within the bounded-fidelity rejection-sampling model --- more than a century of runtime on the Frontier supercomputer --- to collect a 106-sample ensemble, which takes only 19\,s on Nighthawk r2. To our knowledge, this is the first demonstration of quantum advantage for a vanilla random-circuit sampling on a commercially and broadly accessible quantum processor that most non-expert quantum computer users can easily replicate.
Universal statistical laws are a hallmark of quantum chaos. A natural route to probing them in quantum circuits is offered by the statistics of output probabilities, which for sufficiently deep chaotic circuits approach the Porter--Thomas distribution. Here we show, theoretically and experimentally, that the approach to this limit is itself universal, and is organized into geometry-dependent universality classes. At shallow depths, growing only logarithmically with system size, we derive universal output-probability distributions that differ markedly from Porter--Thomas statistics, and we test them on a programmable superconducting processor. Two-dimensional lattices, open one-dimensional chains, and periodic rings exhibit distinct universal forms, retaining signatures of geometry and boundary topology within the same logarithmic-depth regime. Within each class, the distributions depend on only two parameters: an effective many-body Thouless scale and the accumulated number of incoherent errors. Extracting these directly from measured bitstring frequencies provides access to scrambling, entanglement growth of the target state, and global fidelity, without reconstructing or classically simulating the implemented circuit. We also identify a noise-driven transition between output statistics retaining system-wide quantum correlations and those reproducible by independent small patches. Our results establish universality beyond Porter--Thomas statistics as a quantitative tool for characterizing noisy quantum processors.