In superconducting quantum circuits, decoherence improvements are frequently obtained through process interventions that simultaneously modify surface chemistry, microstructural topology, and device geometry, leaving mechanistic attribution structurally underdetermined. Predictive materials engineering requires measurable structural statistics to be separated from geometry-dependent coupling coefficients into independently testable factors. We introduce the concept of classical and quantum microstructure. In that context, we formulate a channel-wise separable framework for decoherence in superconducting transmon qubits in which each loss channel is described by a reduced prescriptor. Here, a channel-specific microstructural state variable is determined independently of device geometry, and a geometry-dependent coupling functional is computable from field solutions without reference to surface chemistry. We derive this product form from a spatially resolved kernel representation and establish a perturbative separability criterion that defines the regime where independent variation of the variables is valid. The framework specifies five prescriptor classes for dominant loss pathways in transmon-class devices. Falsifiability is operationalized through a pre-committed 2x2 experimental protocol in which the variables must satisfy independent ratio checks within propagated uncertainty. A Minimum-Dataset Specification standardizes reporting for cross-laboratory inference. Part I establishes the conceptual and mathematical architecture; coordinated experimental validation is reserved for Part II.
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Part I of a two-part series establishing the theoretical and mathematical architecture. 18 pages, 4 figures
In superconducting quantum circuits, decoherence improvements are frequently obtained through process interventions that simultaneously modify surface chemistry, microstructural topology, and device geometry, leaving mechanistic attribution structurally underdetermined. Predictive materials engineering requires measurable structural statistics to be separated from geometry-dependent coupling coefficients into independently testable factors. We introduce the concept of classical and quantum microstructure. In that context, we formulate a channel-wise separable framework for decoherence in superconducting transmon qubits in which each loss channel is described by a reduced prescriptor. Here, a channel-specific microstructural state variable is determined independently of device geometry, and a geometry-dependent coupling functional is computable from field solutions without reference to surface chemistry. We derive this product form from a spatially resolved kernel representation and establish a perturbative separability criterion that defines the regime where independent variation of the variables is valid. The framework specifies five prescriptor classes for dominant loss pathways in transmon-class devices. Falsifiability is operationalized through a pre-committed 2x2 experimental protocol in which the variables must satisfy independent ratio checks within propagated uncertainty. A Minimum-Dataset Specification standardizes reporting for cross-laboratory inference. Part I establishes the conceptual and mathematical architecture; coordinated experimental validation is reserved for Part II.
TSR-Q-1 presents a preregistered and falsifiable experimental protocol designed to test for structured late-time coherence residuals in superconducting transmon qubits. The protocol does not treat generic recoherence, non-exponential decay, or non-Markovian behavior as evidence for the proposed framework, since such phenomena may arise from conventional open-system mechanisms. Instead, it targets a specific normalized temporal scaling law, tₙ/T₂ = nᵏ, with the preregistered theoretical value k* = 1.4706, corresponding to the first two target locations t₂/T₂ = 2.7714 and t₃/T₂ = 5.0310. If the associated amplitude-scaling hypothesis is retained, the predicted ratio is A₃/A₂ ≈ 0.551. The accompanying computational validation package develops the analysis pipeline through five stages: preliminary signal injection, blind null testing, blind injection-recovery, multi-qubit global-k inference, and sensitivity mapping. The synthetic null models include stretched-exponential decay, 1/f^α correlated noise, random-telegraph/TLS-like contributions, slow drift, white noise, and device-to-device variability. These simulations validate the detectability, specificity, and sensitivity of the proposed analysis procedure under the tested synthetic noise families. They do not constitute experimental evidence for the existence of the predicted physical effect. The next stage is a preregistered hardware implementation using superconducting qubits, with device-specific null calibration, blind analysis, systematic controls, held-out replication, and, ultimately, independent experimental replication.
I present a zero-parameter model for predicting the energy relaxation time (T₁) of superconducting transmon qubits derived from the Unified Structural Theory (UST). The model takes the form T₁ = 1/(ω × p_arch × tan δ_material), where the architecture participation ratio comes from published finite-element simulations and the oxide loss tangent comes from a UST-derived disorder model. Validated against 8 well-characterized published devices from four research groups (Yale, Princeton, Beijing, Fermilab/SQMS), the model achieves a mean absolute error of 9.5%, a maximum error of 20.4%, and a log-log correlation of r = 0.989 with zero fitted parameters. The oxide disorder model correctly identifies niobium oxide as the most lossy surface and explains the Fermilab observation that tantalum capping improves T₁ by 2–5×. The model predicts that crystalline superconductor surfaces — which terminate at ordered lattice planes rather than amorphous oxide layers — would reduce surface loss tangent by approximately 200×, yielding T₁ in the 100–200 ms range compared to the current record of 0.6 ms. Ten specific crystalline superconductor compounds satisfying these criteria have been identified by the UST materials prediction pipeline, which previously demonstrated 100% recall on known superconductors without training. Compound identities are protected under U.S. Provisional Patent #63/987,905. The UST framework derives 72 predictions across particle physics, cosmology, and condensed matter from four structural integers {5, 7, 24, 40} with a 93.1% pass rate and zero free parameters.
Abstract Cross-platform comparison of superconducting quantum devices requires statistical care because heterogeneous architectures implement qualitatively different transport mechanisms, couple to distinct microscopic loss channels, and typically operate in different temperature regimes. We present a methodological case study showing how aggregation of data across platforms can mask qualitatively different within-architecture temperature dependencies when platform identity is confounded with operating temperature. To enable controlled comparison, we introduce two scaling parameters: a dimensionless normalized temperature T∗=kBT/(hf) and a resistance-like decoherence parameter A=(hf/eIc)(lnQ/2π). We develop a detailed physical argument for why the baseline value of A is expected to be architecture-dependent, focusing on the distinct roles of Cooper-pair tunneling in SIS junctions, Andreev bound states in SNS junctions, ferromagnetic layer effects in SIsFS devices, and confinement effects in nanowire junctions. Applying this framework to published data from five distinct junction architectures (Transmon SIS, conventional SIS, SIsFS, planar SNS, and nanowire SNS; N=23 points from five independent studies), we find that the pooled dataset exhibits a weak positive correlation between A and T∗ (r=0.085, p=0.70). However, when stratified by architecture, within-group correlations reveal qualitatively different temperature dependencies: SIsFS shows strong positive dependence (308.4±22.6Ω, p=0.047), planar SNS shows strong positive dependence (205.6±11.6Ω, p=0.036), while transmons show near-zero dependence (−7.2±17.3Ω, p=0.688). Two architectures show positive slopes that reach statistical significance despite small samples (n=3 each), though these results are sensitive to individual data points (see Appendix C). Analysis of variance confirms that architecture explains the dominant share of variance (ANOVA F4,18=670.7, p<0.0001; ICC ≈0.98). Decomposition of A reveals that the 1/Ic term accounts for the factor-of-6.6 variation across architectures (r=−0.94 with logIc), while the lnQ term varies by only 30\%. We argue that these observations are physically expected from architecture-specific transport and loss mechanisms, and we outline experimental designs with overlapping temperature sweeps that could disentangle temperature dependence from platform identity in future benchmarking efforts. All data, extraction uncertainties, and analysis code are provided in the appendices to ensure reproducibility.
This paper introduces a phenomenological model for non-thermal decoherence in quantum devices based on an effective environmental “trace” parameter that captures local density and mechanical structure. We show that mass distribution, rigidity, and geometry can contribute additively to a device’s decoherence rate, independent of temperature. The framework explains several observed features in superconducting and trapped-ion platforms, including temperature plateaus, geometry sensitivity, and coherence variations linked to mechanical layout. The paper provides five falsifiable predictions and immediate engineering guidelines for improving coherence in current quantum hardware. The model requires no modification of quantum mechanics and is fully compatible with standard open-system theory. Includes manuscript and source files.
Decoherence and parameter fluctuations are two of the mayor obstacles for solid-state quantum computing. In this work, decoherence in superconducting qubits of the transmon type is investigated. For this purpose, a time-multiplexed measurement protocol was developed and applied in long-term measurements. The resulting simultaneous measurement of the qubit's relaxation and dephasing rate, as well as its resonance frequency enables analysis of correlations between these parameters. A spectral noise analysis complements these measurements. Together, the results agree well with the interacting defect model of two-level-systems and yield information about the microscopic origin of the intrinsic decoherence mechanisms in Josephson qubits. Our measurements show inherent correlations between dephasing and fluctuations in qubit frequency on the timescale of seconds to days, which is attributed to the influence of individual defects, located close to conductor edges. Cross-correlation and spectral noise analysis confirm this interpretation and ascribe the source of fluctuation to interactions between thermal fluctuators and surface defects. Single defects reducing the coherence of qubits by up to one order of magnitude are a major challenge for future quantum computers. Non-tunable qubits are intrinsically insensitive to some decoherence channels and thus ideal for this fundamental analysis. However, to widen the focus and contrast the results of different material systems, we pursue the fabrication of voltage controlled gatemon qubits. In the course of this work, the theoretical foundation and technical implementation of transmon qubits based on regular Josephson weak links, and semiconducting nanowires is given. The experimental design and measurement setup are explained in detail. Our findings make continuous re-calibration a necessity in today's solid-state qubits, although new materials or processing techniques might mitigate the problem. However, the results of this work imply that fundamental improvements of qubit parameter stability are necessary in order to realize scalable and coherent qubit circuits.
Quantum error correction (QEC) relies on redundancy to combat decoherence, yet resource overhead remains the primary barrier to scalability—leading surface-code architectures require O(10³) physical qubits per logical qubit. We propose a complementary approach inspired by Radial Coherential Dynamics (RCD), where decoherence suppression emerges from geometric coupling to a coherential substrate rather than brute isolation. Leveraging the RCD principle that effective coupling strengths scale with √α (where α ≈ 1.3×10⁻⁴ is the universal coherential parameter), we model a "coherential qubit" whose effective dephasing rate is topologically suppressed by √α ≈ 0.0114. Numerical simulation using QuTiP confirms an **87.7× improvement in coherence time** compared to a standard qubit under equivalent environmental coupling. For typical trapped-ion or superconducting qubits with T₂ = 10 μs, RCD predicts **T₂(RCD) ≈ 877 μs**. This constitutes a **falsifiable prediction testable on current hardware platforms**. We present this as a minimal toy model under pure dephasing conditions, intended as an upper-bound estimate rather than a complete QEC protocol. Nevertheless, the results suggest that topological quantum codes (surface codes, color codes) may approximate natural coherential attractors, offering a geometric pathway toward passive fault tolerance with reduced overhead. Framework: Radial Coherential Dynamics (RCD)Author: Arturo Cerezo García (ORCID: 0009-0007-4739-4990)