Quantum decoherence is universally assumed to follow Markovian (simple exponential) dynamics in analog quantum processors, yet this assumption has never been experimentally tested. We report the first measurement of the stretched exponential parameter β characterizing coherence decay on an analog quantum platform. Using QuEra's Aquila Rydberg atom processor, we measure β = 3.52 ± 1.05 across three system sizes (N=4, 6, 8 atoms), significantly exceeding values observed on gate-based superconducting platforms (β = 1.27 ± 0.25, IBM Quantum). This 2.8-fold difference demonstrates fundamental platform-dependent variations in decoherence mechanisms. The observed super-exponential decay (β > 2.5) indicates strong non-Markovian effects in neutral atom systems, contradicting the standard Markovian assumption. We observe a trend toward larger β values with increasing system size, suggesting many-body correlation effects. These results establish β as a platform-dependent observable and open new directions for characterizing decoherence in quantum processors.
Quantum decoherence is universally assumed to follow Markovian (simple exponential) dynamics in analog quantum processors, yet this assumption has never been experimentally tested. We report the first measurement of the stretched exponential parameter β characterizing coherence decay on an analog quantum platform. Using QuEra's Aquila Rydberg atom processor, we measure β = 3.52 ± 1.05 across three system sizes (N=4, 6, 8 atoms), significantly exceeding values observed on gate-based superconducting platforms (β = 1.27 ± 0.25, IBM Quantum). This 2.8-fold difference demonstrates fundamental platform-dependent variations in decoherence mechanisms. The observed super-exponential decay (β > 2.5) indicates strong non-Markovian effects in neutral atom systems, contradicting the standard Markovian assumption. We observe a trend toward larger β values with increasing system size, suggesting many-body correlation effects. These results establish β as a platform-dependent observable and open new directions for characterizing decoherence in quantum processors.
We report evidence consistent with non-exponential decoherence in superconducting transmon qubits. Ramsey interferometry data from five qubits on IBM Quantum hardware show that a stretched-exponential model f(t) = exp(-(t/T2 ) beta) fits the observed decay better than the standard exponential (beta = 1). On our primary qubit (Q0), we measure beta = 2.06 with R2 = 0.9964 versus R2 = 0.9586 for the exponential, with Bayesian Information Criterion favoring the stretched model by 46 units. While non-exponential decay in superconducting qubits has been previously observed in the context of 1/f noise [4], the present work provides a systematic multi-qubit characterization with a fully reproducible protocol and proposes a falsifiable geometry-dependent prediction (RAB != 1) that distinguishes this framework from collapse-model alternatives.
This study presents a reanalysis of high-precision neutron interferometry data from the Institut Laue-Langevin (ILL), revealing a significant deviation from the traditionally expected exponential decoherence. The interference visibility exhibits a stretched-exponential decay, characterized by V(t)=V0exp[−(t/τcoh)1+ε] with a measured ε=0.18±0.08, in agreement with the theoretical prediction of ε=0.23±0.02. These results provide the first experimental support for the Quantum Phase Interpretation (QPI), in which quantum systems evolve through dynamical phases rather than static states. The phase-based model achieves a substantially better fit than conventional collapse models, with a 3.9-fold improvement in χ2, and aligns closely with the theoretical framework of nonlinear phase diffusion. The study has significant implications for the foundations of quantum mechanics, offering new insights into decoherence mechanisms, the measurement problem, and the emergence of classicality from quantum phase dynamics. Proposed future experiments aim to test phase evolution across different quantum systems, including photons, neutrons, and quantum dots. Keywords: Quantum Phase, Neutron Interferometry, Decoherence, Non-Exponential Decay, Quantum Foundations, Phase Dynamics, Measurement Problem
Analog quantum processors based on Rydberg atom arrays are a powerful platform for many-body quantum simulation, combinatorial optimization, and graph machine learning. As these devices become increasingly accessible, establishing confidence in their outputs requires predictive models that quantitatively connect microscopic hardware imperfections to empirical results. Here, we present a noise-aware emulation framework that propagates the dominant noise mechanisms throughout the full computation cycle to predict device behavior. We validate the framework by benchmarking two representative protocols, quantum annealing and post-quench dynamics, on three Pasqal quantum processors where classical simulations still provide ground truth. Across all three devices, the measured observables fall within the uncertainty envelopes predicted by the emulator. Beyond reproducing the data, the framework isolates which physical mechanism dominates in each operating regime, provides quantitative guidance for algorithm design and hardware improvements, and establishes a foundation for verifying analog processors in regimes beyond classical reach.
Preprint: This paper derives quantitative bounds on measurement windows for finite-capacity observers extracting information from decohering quantum systems, extending standard decoherence theory to realistic experimental constraints. Main Result: For Gaussian-Markovian decoherence with exponential information decay I(t) = I₀ exp(-2Γt), bounded-capacity observers lose access to system distinctions when mutual information drops below detection threshold ε, yielding measurement window: τ_c = (1/2Γ) log(α C_A / ε) where Γ is decoherence rate [s⁻¹], C_A is observer capacity [bits] defined via Shannon formula (bandwidth × log₂(SNR) × integration time), ε is detection threshold [bits], and α ~ 0.1-1 is a model-dependent constant from spectral decomposition of environmental information. This establishes logarithmic capacity-scaling: doubling detector quality extends measurement windows by only ~0.35/Γ seconds, implying diminishing returns from capacity improvements. Experimental Predictions: For state-of-the-art circuit QED (superconducting transmon qubits, T₁ = 100 μs, bandwidth Δf = 10 MHz, SNR = 10), the framework predicts τ_c ~ 4-10 μs. Varying bandwidth from 1-30 MHz (capacity C_A ∈ [3, 90] bits) produces measurable Δτ_c ≈ 1.7 μs variation (5-10% of coherence time). Five experimental tests discriminate capacity-scaling from standard decoherence: ∙ Tests 1-3: Verify logarithmic capacity-scaling, inverse rate-dependence, threshold-dependence ∙ Test 4: Multi-observer non-redundancy (at most one narrowband detector succeeds) ∙ Test 5: Capacity-dependent redundancy buildup (primary discriminating signature) Key Contributions: ∙ First quantitative analysis of Zurek's pre-objective phase under explicit finite-resource constraints ∙ Capacity-scaling law connecting Shannon information theory to quantum measurement dynamics ∙ Operational definitions ensuring falsifiability (capacity, threshold, mutual information defined via measurement protocols) ∙ Concrete numerical predictions for three platforms (circuit QED, spin qubits, optomechanics) with resource estimates ∙ Design principle: environmental shielding (linear benefit in τ_c) outperforms detector improvement (logarithmic benefit) when both options available Technical Approach: The bound follows from threshold-crossing analysis of exponential decay with capacity-limited initial information I₀ = α C_A, justified via spectral decomposition of environmental information under flat-spectrum approximation for narrowband observation. All parameters (Γ, C_A, ε) are operationally defined and independently measurable, avoiding circularity. Extensions to non-Markovian dynamics (memory kernels), scrambling systems (black holes, many-body chaos), and non-Gaussian noise (Lévy flights, 1/f noise) are discussed with conjectured scaling laws. Scope: The bound applies specifically to Gaussian-Markovian systems (harmonic oscillators, qubits in dispersive limit, weak continuous measurement with memoryless baths). Circuit QED provides optimal testbed due to tunable Purcell filters (bandwidth control), high coherence times (T₁ > 300 μs achieved), and multiplexed readout infrastructure (5+ independent detectors demonstrated). Validity requires α C_A > ε (initial information exceeds threshold); domain violations occur when capacity too small, threshold too high, or coupling too weak. Relation to Prior Work: Zurek's Quantum Darwinism (2003-2009) explains asymptotic objectivity emergence through environmental redundancy but assumes unbounded observers (C_A → ∞, t → ∞). This work analyzes the complementary finite-resource regime (C_A < ∞, t ~ τ_c), providing first capacity-parameterized bound on pre-objective phase duration. Framework is interpretation-neutral—compatible with Copenhagen, Many-Worlds, Bohmian mechanics, and relational quantum mechanics. Philosophical implications (process ontology, observer-dependent reality, impermanence) are explored but clearly separated from testable predictions. Methods: Open quantum systems theory, Shannon information theory, operational quantum measurement, circuit QED experimental physics, numerical prediction for realistic parameters. Content: Complete 90-page manuscript with axiomatic framework (§2), narrowband observation model (§3), main theorem with proof (§4), numerical predictions (§5), five experimental falsification tests (§6), detailed Quantum Darwinism comparison (§7), extensions and limitations (§8), interpretive options (§9), and honest assessment (§10). Includes 77 references and operational definitions for all information-theoretic quantities. Target Audience: Quantum foundations researchers, experimental quantum physicists (circuit QED, trapped ions, quantum dots), quantum information theorists, philosophers of physics interested in measurement and objectivity.
We investigate the validity of exponential models in the analysis of Ramsey coherence measurements and show that finite environmental memory is consistent with a systematic bias in the extracted decoherence rate. Starting from a system–bath Hamiltonian, we derive a finite-memory decoherence function using a second-order cumulant expansion under the assumption of Gaussian noise with finite correlation time. The resulting dynamics exhibit a time-dependent effective decay rate, reducing to exponential behavior only in the long-time limit. We derive an explicit closed-form expression for the decoherence rate extracted by least-squares exponential fitting over a finite time window [0, T], as an explicit function of both T and the environmental correlation time τ_c. We show that the extracted rate γ_fit(T) strictly underestimates the intrinsic decoherence rate γ for all finite T > 0, with the deficit decaying as T⁻¹ in the long-window limit, while in the short-window limit the fitted rate scales linearly with T , a regime not directly accessible experimentally due to limited signal contrast at early times. The central implication is that decoherence rates extracted from exponential fits are not intrinsic observables in non-Markovian environments: they encode a protocol-dependent effective average that depends systematically on the chosen fitting window. The conventionally reported coherence time T₂* = 1/γ_fit is therefore protocol-dependent in non-Markovian environments. Finally, we connect this behavior to experimentally observed non-exponential decay profiles and noise spectra, providing a unified framework for interpreting deviations from exponential coherence decay. These results identify a structural limitation in standard Ramsey analysis and motivate the use of physically grounded models in extracting decoherence parameters.
We present a comprehensive analytical and numerical study of time-dependent decoherence in open quantum systems, focusing on a single-qubit model with time-varying Lindblad dissipation rates. Employing a master equation framework, we derive exact solutions for the evolution of off-diagonal density matrix elements and characterize the emergence of robust pointer states. Our findings reveal an initial rapid coherence decay followed by a gradual slowdown, mirroring experimental trends observed in superconducting qubits influenced by quasiparticle dynamics and in photonic cavities subject to fluctuating environments. By incorporating real experimental parameters and validating the model through quantum simulations using QuTiP, we provide a robust quantitative tool for analyzing decoherence in quantum technologies. This extended model addresses limitations in static-rate approximations, offering insights into non-Markovian effects without resolving the measurement problem, and suggests extensions to multi-qubit systems.