Manuscript submitted to Physical Review Letters (es2026aug09_746) with Supplemental Material. Using Phase-Anchored State Multiplexing (PASM) on two IBM Heron r2 processors (ibm_marrakesh, ibm_kingston), we report an independent realization of a classical prethermal discrete time crystal on superconducting hardware through a phase-anchored protocol distinct from Floquet-driven realizations. Signature: mutual information between identically prepared qubits that peaks at 0.159 at three qubits, is modulated by the controlled-phase angle (max at phi = pi), reaches 0.722 in the PASM-H variant, is reproducible across ten replicas (Z = 39.6 sigma), is independent of physical qubit separation (Z = 34 sigma), survives controlled noise, and vanishes in control protocols (MI = 0.00013). Quantum state tomography shows the correlation is classical (quantum discord < 0.01). Full experimental record: 14 experiments, 186 circuit executions, 1.5 million measurements. A residual MI at phi = pi in the echo variant (0.0062, theory ~ 0) is reported transparently and earmarked for follow-up tests.
Manuscript submitted to Physical Review Letters (es2026aug09_746) with Supplemental Material. Using Phase-Anchored State Multiplexing (PASM) on two IBM Heron r2 processors (ibm_marrakesh, ibm_kingston), we report an independent realization of a classical prethermal discrete time crystal on superconducting hardware through a phase-anchored protocol distinct from Floquet-driven realizations. Signature: mutual information between identically prepared qubits that peaks at 0.159 at three qubits, is modulated by the controlled-phase angle (max at phi = pi), reaches 0.722 in the PASM-H variant, is reproducible across ten replicas (Z = 39.6 sigma), is independent of physical qubit separation (Z = 34 sigma), survives controlled noise, and vanishes in control protocols (MI = 0.00013). Quantum state tomography shows the correlation is classical (quantum discord < 0.01). Full experimental record: 14 experiments, 186 circuit executions, 1.5 million measurements. A residual MI at phi = pi in the echo variant (0.0062, theory ~ 0) is reported transparently and earmarked for follow-up tests.
Public pre-registration (N47Lab method: criteria written BEFORE the data, not negotiable afterwards) of a search for a response of the PASM (Phase-Anchored State Multiplexing) phase-imprint observable to the lunisolar harmonic tidal field on a superconducting quantum processor. Hypothesis: if the phase imprint is a property of the substrate sensitive to external gravitational stimuli, the PASM mutual information must modulate coherently with the harmonic tidal potential (constituents M2, S2, N2, K1, O1, Mf, Mm). If the imprint is insensitive to the environment, the MI spectrum is flat at tidal frequencies. No intermediate result modifies this hypothesis. Foundation (ANALOGICAL motivation, not proof): atomic clocks respond to the lunisolar tidal field (Qin & Cheng, Astron. J. 158, 262 (2019), DOI 10.3847/1538-3881/abc06f): the tidal field is a real, modeled, measurable signal on precision quantum systems. The direct channel (qubit frequency) is ~11 orders of magnitude below device noise: the analogy does NOT extend to that channel. The tested channel is the temporal statistical modulation of the PASM observable (shared MI), never evaluated in the literature (verification 31/08/2026): neither tested, nor discarded, nor considered - documentary silence, not a verdict. Method: session >= 30 days, one point every 30-60 minutes with rotated schedules (decorrelation from the solar day), fixed backend (ibm_marrakesh), 2 replicates per point, MI with timestamp, theoretical tidal reference from ephemerides (no ocean tides). Analysis: Lomb-Scargle periodogram on MI(t), significance vs null (permutations + FDR). Decision criteria (written first, not negotiable after data): C1 Presence: spectral power at M2 frequency significant vs null; C2 Discrimination: M2 and S2 resolved as distinct lines; C3 Ratio: M2/S2 power compatible with 2.17 within +/-50%; C4 Negative control: lines at NON-tidal frequencies must be absent (if present -> instrumental artifact, outcome NOT VALID). Pre-registered decision: >= 2 of 3 criteria (C1-C3) + clean C4 -> TIDAL RESPONSE; otherwise -> NOT DETECTED (environmental negative control, useful and publishable result). The test has value in both outcomes. Declared limits: hunt, not guarantee; 'NOT DETECTED' = non-detection at the given sensitivity (power, not absence); thermal drift and daily calibrations monitored and decorrelated. Context note (NOT a criterion): optional post-data coherence check - cross-correlation of MI(t) with public atomic-clock phase series (common M2 harmonic). It does NOT enter the pre-registered decision: criteria C1-C4 are the only ones. No modification to the criteria after session start, except formal ex-ante amendment. Related: MatterMemory PASM data V2 (DOI 10.5281/zenodo.22134568), pasm-experiments (DOI 10.5281/zenodo.21830151), research-timeline (DOI 10.5281/zenodo.21855315).
We derive analytically that the optimal feedforward phase for ZZ-coupling correction in superconducting qubits is given by the argument of the first circular moment of the accumulated phase distribution: φ* = arctan(S/C), where C = ⟨cos φ⟩ and S = ⟨sin φ⟩. A negative second derivative proves this is always a maximum. We measure GPS = P_ff − P_ref on IBM Heron r2 processors (ibm_kingston, ibm_marrakesh; five qubit pairs) and IQM Garnet (Crystal 20). A robust empirical invariant is observed: π ν_ZZ τ* ≈ const ≈ 0.873 rad, confirmed across five independent IBM configurations (π ν_ZZ τ* = 0.873 ± 0.001 rad). A preliminary τ-scan on IQM Garnet shows a GPS sign reversal consistent with a zero-crossing near φ = 0.873 rad. The result establishes a robust empirical invariant within superconducting architectures, enabling feedforward calibration without full phase tomography. Related work:- EEDT Protocol: https://doi.org/10.5281/zenodo.19029431- Bell Decay Clock: https://doi.org/10.5281/zenodo.19367565- Software (Quantum-6502): https://doi.org/10.5281/zenodo.19160835
The simulation of non-equilibrium quantum many-body systems on noisy intermediate-scale quantum (NISQ) processors represents a central challenge and opportunity in modern condensed matter physics. Periodically driven (Floquet) systems can host exotic phases of matter with no equilibrium counterpart, most notably discrete time crystals (DTCs) characterized by spontaneous breaking of discrete time-translation symmetry and robust subharmonic responses. However, the realization of DTCs faces fundamental obstacles: driven many-body systems generically absorb energy and thermalize to an infinite-temperature state, destroying time-crystalline order. Two primary mechanisms have been identified to stabilize DTCs—many-body localization (MBL) through strong disorder, and Floquet prethermalization wherein high-frequency driving suppresses heating over exponentially long timescales. This work investigates the digital quantum simulation of prethermal DTCs on current superconducting quantum processors, with a focus on understanding and mitigating the impact of hardware noise. Recent experiments on 133-qubit heavy-hexagonal devices have demonstrated the realization of clean two-dimensional DTCs and incommensurately modulated DTCs (IM-DTCs) using kicked Ising models, observing period-doubling oscillations persisting for up to 100 Floquet cycles . Crucially, these simulations reveal that quantum noise, often perceived as detrimental, can in certain regimes stabilize novel prethermal DTC phases—a phenomenon identified as noise-induced DTCs supported by symmetry charge pumping or random gate fluctuations . The heavy-hexagonal lattice geometry, compared to square lattices, exhibits significantly slower quantum scrambling, thereby extending the prethermal plateau and enhancing DTC stability. We address two key challenges limiting the scalability of DTC simulations: limited qubit connectivity and environmental noise. By leveraging the universality of native gate sets, we demonstrate how to implement effective couplings among physically disconnected qubits at the cost of increased circuit depth, enabling the study of interaction-range effects on DTC stabilization—a phenomenon previously unobserved experimentally . Furthermore, we benchmark the performance of error mitigation protocols based on depolarising noise models, achieving excellent agreement between error-mitigated hardware data and tensor-network simulations in regimes where classical computations remain tractable . Our results highlight the complementary roles of quantum hardware and classical simulation: quantum processors provide access to regimes where entanglement growth outpaces tensor-network methods, while careful validation against classical benchmarks ensures the reliability of quantum outcomes. This study establishes a concrete pathway for using NISQ devices as experimental platforms for synthesizing and probing novel non-equilibrium quantum phases, advancing both our fundamental understanding of Floquet many-body dynamics and the practical capabilities of quantum simulation. The identification of noise as an active ingredient in phase stabilization suggests new directions for quantum engineering of spatiotemporal orders on near-term hardware.
Periodically driven interacting quantum many-body systems can exhibit long-lived prethermal dynamics, where local observables retain coherent structure even as entanglement and operator complexity grow. Accessing this regime at the system sizes and times needed to determine physical properties of the prethermal state remains a central challenge: state-of-the-art classical methods become unreliable, while noise in quantum hardware degrades observable expectation values. Here we overcome these limitations for a Floquet Ising magnet realized on a heavy-hex lattice. Using the advanced error mitigation software QESEM on an IBM Heron r3 superconducting quantum processor, we measure magnetization dynamics with percent-level precision and resolve long-lived subharmonic prethermal oscillations in systems of up to 74 qubits. These experiments reach regimes for which leading tensor-network simulations fail to converge, while sparse Pauli-path simulations remain strongly truncation dependent despite extensive computations on advanced GPUs and the Fugaku supercomputer. Leveraging this quantum-accessible regime, we extend finite-size scaling to larger systems and find an unexpectedly slow decrease of the oscillation amplitude with system size, providing strong evidence that this oscillatory response persists in the thermodynamic limit of heavy-hex ladders. A hierarchy of mitigation and validation tests, including unbiased error mitigation, agreement between independent mitigation estimators, noise-model validation on the superconducting hardware, and cross-platform corroboration at selected Floquet cycles on Quantinuum System Model H2 and Quantinuum Helios trapped-ion hardware, supports the reliability of these findings. Our work establishes error-mitigated quantum processors as quantitative scientific instruments for discovering new physics in non-equilibrium quantum matter.
This preprint presents a Kuramoto--XY synchronisation study with heterogeneous natural frequencies, simulator baselines, and ledgered IBM Heron r2 evidence. A Rust/PyO3-assisted pipeline supports entanglement entropy, Krylov complexity, OTOC scrambling, and Floquet discrete-time-crystal diagnostics for 2--16 qubit systems. The manuscript reports finite-size diagnostics consistent with Berezinskii--Kosterlitz--Thouless scaling in the small systems studied, including a periodic-boundary central-charge estimate near c = 1 at n = 8, while explicitly noting finite-size drift at larger sizes. It also records subharmonic Floquet response, non-ergodic level-spacing behaviour for heterogeneous frequencies, and a hardware-anchored scaling analysis that bounds exact Hilbert-space simulation costs. The record archives the manuscript source and PDF. Legacy IBM artefacts are treated as committed artefact-path evidence rather than aggregate validation, and the resource-boundary discussion is not promoted as a broad quantum-advantage claim because classical Rust Kuramoto ODE baselines remain faster in the measured observable-level regime.
ABSTRACT We report a systematic, measurement-induced irreversibility in superconducting quantum circuits that is not accounted for by any tested conventional noise model. Using IBM Quantum processors (ibm_marrakesh and ibm_kingston), we implement a time-reversal protocol in which mid-circuit measurements are inserted between a unitary U and its inverse U†. The fidelity deficit ΔF = F(dummy) − F(meas) grows linearly with measurement count M, reaching ΔF = 0.235 (22.2σ) and ΔF = 0.164 (24.0σ) at M = 8 on the two processors. Three independent controls rule out conventional noise sources: (1) T-independence of the spectator-qubit phase shift (dA ≈ +0.10 at T = 40 and 80 μs) eliminates crosstalk and leakage; (2) a non-Markovian symmetry test (spread = 1.5σ) eliminates decoherence asymmetry; and (3) cross-backend reproducibility of the linear ΔF(M) scaling eliminates hardware-specific measurement noise. The three observations share a common structural feature: the irreversibility is tied to discrete measurement events rather than free-evolution time, accumulates proportionally to their count, and reproduces across independent hardware. We report these observations as experimental evidence consistent with the interpretation that the imaginary unit i in the Schrödinger equation reflects a physically real internal structure of time, and that quantum measurement drives an irreversible projection of that structure onto the real axis. This interpretation is developed from first principles in Sec. II and connected to an existing theoretical framework [13] in Sec. VI. Keywordsquantum computing, mid-circuit measurement, complex time, irreversibility, IBM Quantum, time-reversal protocol