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SPDX-License-Identifier: AGPL-3.0-or-later

Commercial license available

© Concepts 1996–2026 Miroslav Šotek. All rights reserved.

© Code 2020–2026 Miroslav Šotek. All rights reserved.

ORCID: 0009-0009-3560-0851

Contact: www.anulum.li | protoscience@anulum.li

scpn-quantum-control — Analysis API Reference

Analysis API Reference

42 modules for probing quantum synchronization transitions, entanglement structure, topological invariants, and computational complexity of the Kuramoto-XY Hamiltonian.

This is an advanced module reference. Use Stable Facades API and Kuramoto Core Facade for first-path workflows, then drop into this page when a specific analysis probe or low-level diagnostic is needed.

Synchronization Detection

sync_witness — Synchronization Witness Operators

Three Hermitian witness constructions that certify quantum synchronization from hardware measurement counts. No state tomography required.

from scpn_quantum_control.analysis.sync_witness import (
    WitnessResult,
    correlation_witness_from_counts,
    fiedler_witness_from_counts,
    fiedler_witness_from_correlator,
    topological_witness_from_correlator,
    evaluate_all_witnesses,
    calibrate_thresholds,
)
Function Input Output Description
correlation_witness_from_counts X/Y counts, n_qubits, threshold WitnessResult Mean pairwise XY correlator vs threshold
fiedler_witness_from_counts X/Y counts, n_qubits, threshold WitnessResult Algebraic connectivity of correlation Laplacian
fiedler_witness_from_correlator corr_matrix, threshold WitnessResult From pre-computed correlation matrix
topological_witness_from_correlator corr_matrix, threshold, max_dim WitnessResult Persistent H₁ via Vietoris-Rips (requires ripser)
evaluate_all_witnesses X/Y counts, n_qubits, thresholds dict[str, WitnessResult] All three witnesses from one measurement set
calibrate_thresholds K, omega, K_base_range, n_samples dict[str, float] Classical Kuramoto calibration of thresholds

WitnessResult fields: witness_name, expectation_value (negative = synchronised), threshold, is_synchronized, raw_observable, n_qubits.

Full theory and examples: Research Gems — Gem 1.

Bayesian plus bandit search over Kuramoto control candidates, scored by the existing correlation and Fiedler synchronisation witnesses.

from scpn_quantum_control.analysis.witness_discovery import (
    WitnessCandidate,
    WitnessDiscoverySpec,
    discover_kuramoto_witnesses,
    score_witness_candidates,
)
Function Description
discover_kuramoto_witnesses(K_nm, omega, theta0, spec) Run deterministic initial design, RBF Bayesian UCB, and bandit local exploration.
score_witness_candidates(K_nm, omega, candidates) Score fixed candidates through the same witness objective.
WitnessDiscoveryResult.ranked(limit) Return candidates sorted by descending witness score.

The Rust path kuramoto_witness_candidate_features evaluates final order parameter, mean pairwise correlation, and final phases for candidate batches. The Python scorer then evaluates the existing witness objects, so the discovery loop stays connected to the hardware-measurable witness definitions.

RLDiscoveryAgent is a compatibility wrapper around the same production search. It accepts only the wired objective: correlation and Fiedler observables with reward_function="witness_score", positive n_episodes, and no external runner. Unsupported compatibility parameters fail at construction instead of being silently ignored.

sync_entanglement_witness — R as Entanglement Witness

The Kuramoto order parameter \(R\) reinterpreted as an entanglement witness. For separable states, \(R \leq R_{\mathrm{sep}}\). Exceeding the separable bound certifies entanglement.

from scpn_quantum_control.analysis.sync_entanglement_witness import (
    EntanglementWitnessResult,
    R_entanglement_scan,
    R_from_statevector,
    R_separable_bound,
    R_separable_bound_at_energy,
    detect_entanglement_from_R,
)
Function Description
R_from_statevector(psi, n_qubits) Compute \(R = \|(1/N)\sum_i(\langle X_i\rangle + i\langle Y_i\rangle)\|\)
R_separable_bound(n_qubits) Maximum \(R\) achievable by any separable state (= 1.0)
R_separable_bound_at_energy(K, omega, target_energy, n_samples=1000, seed=42, *, max_dense_gib=None) Dense exact max \(R\) over sampled product states at fixed energy
detect_entanglement_from_R(K, omega, n_samples=2000, seed=42, *, max_dense_gib=None) Ground-state witness evaluation with dense exact small-system guard
R_entanglement_scan(K, omega, K_base_range=None, n_K_values=15, n_samples=500, seed=42, *, max_dense_gib=None) Coupling scan of \(R_\mathrm{ground}\) and the energy-constrained separable bound

The returned entanglement_depth is a certified lower bound from this witness: 1 when the separable bound is not violated and 2 when entanglement is certified. The R witness alone does not certify stronger multipartite depth; that requires separate k-producibility bounds or a dedicated depth witness.

critical_concordance — Multi-Probe \(K_c\) Agreement

Runs a finite-size dense exact coupling scan and compares where the order parameter, QFI, spectral gap, and concurrence-graph probes localise the same coupling region.

from scpn_quantum_control.analysis.critical_concordance import (
    critical_concordance,
    ConcordanceResult,
)

critical_concordance(omega, K_topology, k_range=None, concurrence_threshold=1e-4, *, max_dense_gib=None) returns ConcordanceResult with fields: k_values, R_values, qfi_values, gap_values, fiedler_values, n_entangled_pairs, k_c_from_gap, k_c_from_qfi, k_c_from_fiedler, k_c_from_R_deriv, and concordance_spread.

Phase Transition Probes

qfi_criticality — Quantum Fisher Information at \(K_c\)

QFI diverges where the spectral gap closes — the synchronization transition is a metrological sweet spot.

from scpn_quantum_control.analysis.qfi_criticality import (
    qfi_vs_coupling,
    QFICriticalityResult,
)

qfi_vs_coupling(K, omega, K_base_range=None, n_K=20) → QFICriticalityResult with: K_values, qfi_values, gap_values, peak_K (coupling at max QFI).

entanglement_percolation — Finite-Size Entanglement Percolation

Compares the concurrence-graph percolation point with a selected finite-size order-parameter threshold. This is a dense exact diagnostic, not a standalone thermodynamic-limit proof.

from scpn_quantum_control.analysis.entanglement_percolation import (
    percolation_scan,
    PercolationScanResult,
)

percolation_scan(omega, K_topology, k_range=None, concurrence_threshold=1e-4, R_threshold=0.5, *, max_dense_gib=None) → PercolationScanResult with: k_values, fiedler_values, max_concurrence, mean_concurrence, n_entangled_pairs, R_values, k_percolation, and k_sync.

berry_phase — Berry Connection and Fidelity Susceptibility

Finite-size dense exact scan of ground-state overlaps. On the one-dimensional open coupling path, the accumulated Berry connection is gauge-dependent; the fidelity and fidelity susceptibility are the gauge-invariant diagnostics.

from scpn_quantum_control.analysis.berry_phase import (
    berry_phase_scan,
    BerryPhaseResult,
)

berry_phase_scan(omega, K_topology, k_range=None, *, max_dense_gib=None) → BerryPhaseResult with: k_values, berry_connection, berry_curvature, accumulated_phase, fidelity, fidelity_susceptibility, spectral_gap, and curvature_peak_k.

finite_size_scaling — Finite-Size Gap-Minimum Scaling

Fits finite-size gap-minimum estimates to a BKT-motivated \(K_c(N) = K_c(\infty) + a/(\ln N)^2\) ansatz and a power-law comparison model.

from scpn_quantum_control.analysis.finite_size_scaling import (
    finite_size_scaling,
    FSSResult,
)

finite_size_scaling(system_sizes=None, k_range=None, *, max_dense_gib=None) → FSSResult with: system_sizes, k_c_values, gap_min_values, k_c_extrapolated_bkt, and k_c_extrapolated_power.

adiabatic_preparation — Adiabatic State Preparation

Finite-size dense exact adiabatic path from a weak-coupling initial ground state to the target XY Hamiltonian. Computes instantaneous gap and fidelity along the selected schedule.

from scpn_quantum_control.phase.adiabatic_preparation import (
    adiabatic_ramp,
    AdiabaticResult,
)

adiabatic_ramp(omega, K_topology, K_target, T_total=10.0, n_steps=50, *, max_dense_gib=None) → AdiabaticResult with: times, K_schedule, fidelity, gap, final_fidelity, min_gap, min_gap_K.

Entanglement and Correlations

entanglement_entropy — Half-Chain Entropy and Schmidt Gap

Entanglement entropy and Schmidt gap across the synchronization transition. At BKT criticality, entropy follows CFT scaling \(S \sim (c/3)\ln L\) with \(c = 1\).

from scpn_quantum_control.analysis.entanglement_entropy import (
    entanglement_vs_coupling,
    EntanglementScanResult,
)

entanglement_vs_coupling(omega, K_topology, k_range=None) → EntanglementScanResult with: k_values, entropy, schmidt_gap, spectral_gap, entropy_peak_K, schmidt_gap_min_K.

Rust acceleration: Hamiltonian construction via build_xy_hamiltonian_dense (Qiskit-free).

entanglement_spectrum — Full Entanglement Spectrum

Computes the full entanglement spectrum (all Schmidt coefficients) and estimates the CFT central charge from the entropy scaling.

from scpn_quantum_control.analysis.entanglement_spectrum import (
    entanglement_spectrum,
    cft_central_charge,
)

pairing_correlator — Richardson Pairing \(\langle S^+_i S^-_j\rangle\)

Detects Richardson pairing (the superconducting analogue of synchronization) via spin-raising/lowering correlators. Strong pairing = synchronised phase.

from scpn_quantum_control.analysis.pairing_correlator import (
    pairing_map,
    pairing_vs_anisotropy,
    PairingResult,
)

pairing_map(omega, K_topology, K_base, delta=0.0, *, max_dense_gib=None) → PairingResult with the full pairing matrix, maximum/mean pairing, topology correlation, qubit count, anisotropy, and base coupling.

pairing_vs_anisotropy(omega, K_topology, K_base, delta_range=None, *, max_dense_gib=None) forwards the dense budget to every XXZ ground-state solve in the scan.

Quantum Chaos and Dynamics

otoc — Out-of-Time-Order Correlator

Core OTOC computation: \(F(t) = \langle W^\dagger(t) V^\dagger W(t) V\rangle\).

from scpn_quantum_control.analysis.otoc import (
    compute_otoc,
    OTOCResult,
)

compute_otoc(K, omega, times, w_qubit=0, v_qubit=None) → OTOCResult with: times, otoc_values, lyapunov_estimate, scrambling_time.

Rust acceleration: When scpn_quantum_engine is installed, OTOC uses eigendecomposition + rayon-parallel time loop (\(O(d^2)\) per time point vs \(O(d^3)\) scipy.expm). Hamiltonian construction uses build_xy_hamiltonian_dense (bitwise, Qiskit-free). 10-50× faster for n ≤ 8.

otoc_sync_probe — OTOC Scan Across \(K_c\)

Scans OTOC diagnostics vs coupling strength to detect the synchronization transition via chaos measures.

from scpn_quantum_control.analysis.otoc_sync_probe import (
    otoc_sync_scan,
    OTOCSyncScanResult,
)

otoc_sync_scan(K, omega, K_base_range=None, n_K_values=15, t_max=2.0) → OTOCSyncScanResult with: K_base_values, lyapunov_values, scrambling_times, otoc_final_values, R_classical, peak_scrambling_K.

spectral_form_factor — SFF and Level Statistics

Spectral Form Factor diagnoses chaos via Random Matrix Theory level statistics.

from scpn_quantum_control.analysis.spectral_form_factor import (
    spectral_form_factor,
    level_spacing_ratio,
    SFFResult,
)
Function Description
spectral_form_factor(H, t_values) \(g(t) = \|\mathrm{Tr}(e^{-iHt})\|^2 / d^2\)
level_spacing_ratio(H) Mean ratio \(\bar{r}\): Poisson ≈ 0.386, GOE ≈ 0.536

loschmidt_echo — Loschmidt Echo and DQPT

Dynamical Quantum Phase Transitions detected via non-analyticities in the Loschmidt return rate \(\lambda(t) = -\ln\mathcal{L}(t)/N\).

from scpn_quantum_control.analysis.loschmidt_echo import (
    loschmidt_echo,
    LoschmidtResult,
)

loschmidt_echo(K, omega, K_i, K_f, times) → LoschmidtResult with: times, echo_values, return_rate, dqpt_times (cusp locations).

Rust acceleration: Hamiltonian construction via build_xy_hamiltonian_dense (Qiskit-free).

krylov_complexity — Operator Spreading Complexity

Lanczos coefficients \(b_n\) and Krylov complexity \(C_K(t) = \sum_n n |\phi_n(t)|^2\). Maximum at \(K_c\).

from scpn_quantum_control.analysis.krylov_complexity import (
    krylov_complexity,
    krylov_vs_coupling,
    KrylovResult,
)

krylov_complexity(H, O_init, t_max=10.0, n_times=100, max_lanczos=50) → KrylovResult with Lanczos coefficients, times, complexity values, peak complexity, and realised Krylov dimension.

krylov_vs_coupling(omega, K_topology, k_range=None, t_max=10.0, n_times=50, *, max_dense_gib=None) builds the dense Hamiltonian/probe workspace under the caller's budget before scanning peak complexity against coupling.

Rust acceleration: Lanczos b-coefficients computed via lanczos_b_coefficients (complex matrix commutator loop in Rust, 5-10× for dim ≤ 256). Hamiltonian via build_xy_hamiltonian_dense.

Quantum Information Measures

qfi — Quantum Fisher Information Matrix

Full QFI matrix for parameter estimation precision bounds.

from scpn_quantum_control.analysis.qfi import (
    quantum_fisher_information,
    spectral_gap,
    precision_bounds,
)
Function Description
quantum_fisher_information(state, generators) QFI matrix \(F_{ij}\)
spectral_gap(H) \(E_1 - E_0\)
precision_bounds(qfi_matrix) Cramér-Rao lower bounds \(\delta\theta_i \geq 1/\sqrt{F_{ii}}\)

QuantumFisherInformation is the observable-wrapper adapter for production metrology calls. When coupling_matrix and natural_frequencies are supplied it routes to the spectral QFI engine and validates that the coupling matrix is square, symmetric, finite-valued, and dimension-compatible with the frequency vector. Optional coupling_pairs must be distinct in-range integer index pairs, and n_measurements must be a positive integer because it rescales the Cramér-Rao precision bound. Counts-derived sync/DLA estimates are exposed only through the explicit allow_proxy_estimate=True diagnostic path and are labelled as proxy values, never as production QFI.

magic_nonstabilizerness — Stabilizer Rényi Entropy

Magic \(M_2 = -\log_2(\sum_P \langle P\rangle^4 / 2^N)\) peaks at \(K_c\) — the critical state is maximally non-classical.

from scpn_quantum_control.analysis.magic_nonstabilizerness import (
    magic_at_coupling,
    magic_vs_coupling,
    MagicResult,
)

magic_at_coupling(omega, K_topology, K_base, *, max_dense_gib=None) computes the dense exact ground state and Stabilizer Renyi entropy at one coupling.

magic_vs_coupling(omega, K_topology, k_range=None, *, max_dense_gib=None) forwards the dense eigensolver budget to every coupling point and returns a MagicScanResult with the scanned values and peak location.

quantum_phi — Integrated Information (IIT)

Quantum integrated information from the Kuramoto-XY ground-state density matrix. compute_quantum_phi(K, omega) computes the minimum mutual information over bipartitions and reports the minimum-information partition.

from scpn_quantum_control.analysis.quantum_phi import (
    compute_quantum_phi,
    PhiResult,
)

IntegratedInformationPhi is the dashboard-facing wrapper. When supplied with coupling_matrix and natural_frequencies, it routes to compute_quantum_phi and returns phi, phi_max, entropy, and partition metadata. Counts-only entropy remains available only via allow_entropy_proxy=True and is labelled entropy_proxy, never phi.

shadow_tomography — Classical Shadow Estimation

\(O(\log M)\) shots for \(M\) observables via random Clifford measurements.

from scpn_quantum_control.analysis.shadow_tomography import (
    random_clifford_shadow,
    estimate_observable,
    ShadowResult,
)

quantum_speed_limit — QSL for BKT Synchronization

Mandelstam-Tamm and Margolus-Levitin speed limits: minimum time to evolve between states across the synchronization transition.

from scpn_quantum_control.analysis.quantum_speed_limit import (
    qsl_vs_coupling,
    QSLResult,
)

qsl_vs_coupling(K, omega, t_target=1.0, K_base_range=None, n_K=15) → QSLResult with: K_base, mt_limits (Mandelstam-Tamm), ml_limits (Margolus-Levitin).

Topological Analysis

quantum_persistent_homology — Full PH Pipeline

Hardware counts → correlation matrix → distance → Vietoris-Rips → persistence diagram → \(p_{H_1}\).

from scpn_quantum_control.analysis.quantum_persistent_homology import (
    counts_to_persistence,
    coupling_scan_persistence,
    PersistenceResult,
    PersistenceScanResult,
)
Function Description
counts_to_persistence(x_counts, y_counts, n_qubits, max_dim=1) Single-point PH from hardware counts
coupling_scan_persistence(K, omega, K_range, ...) \(p_{H_1}\) vs coupling strength

persistent_homology — Classical PH Utilities

Distance matrix construction, Rips filtration, Betti number extraction.

h1_persistence — Vortex Density at BKT

\(H_1\) persistence as a function of coupling — the topological order parameter for the BKT transition.

vortex_binding — Kosterlitz RG Flow

Vortex-antivortex binding energy and Kosterlitz renormalization group flow equations.

Algebraic Structure

dynamical_lie_algebra — DLA Computation

Computes the Dynamical Lie Algebra and its dimension for the Kuramoto-XY Hamiltonian. Result: \(\dim(\mathrm{DLA}) = 2^{2N-1} - 2\) for non-degenerate frequencies.

from scpn_quantum_control.analysis.dynamical_lie_algebra import (
    compute_dla,
    DLAResult,
)

compute_dla(K, omega) → DLAResult with: generators (list of Pauli strings), dimension, n_qubits, predicted_dim (\(2^{2N-1} - 2\)).

dla_parity_theorem — Z₂ Parity Proof

Formal verification that Z₂ parity is the only symmetry of the heterogeneous XY Hamiltonian.

from scpn_quantum_control.analysis.dla_parity_theorem import (
    verify_z2_parity,
    ParityTheoremResult,
)

BKT Phase Analysis

bkt_analysis — Core BKT Diagnostics

Fiedler eigenvalue, \(T_{\mathrm{BKT}}\), \(p_{H_1}\) prediction from coupling structure.

from scpn_quantum_control.analysis.bkt_analysis import (
    bkt_scan,
    BKTResult,
)

bkt_universals — 10 Candidate Expressions for \(p_{H_1} = 0.72\)

Systematic search for the analytical formula behind the universal \(p_{H_1}\) value.

p_h1_derivation — \(A_{HP} \times \sqrt{2/\pi} = 0.717\)

The derivation closing the \(p_{H_1}\) gap to 0.5% accuracy.

phase_diagram — \(K_c\) vs \(T_{\mathrm{eff}}\) Boundary

Full synchronization phase diagram in the coupling-temperature plane.

xxz_phase_diagram — \(K_c\) vs Anisotropy \(\Delta\)

Finite-size gap-minimum diagnostics in the \((K, \Delta)\) plane from XY-like (\(\Delta=0\)) to Heisenberg-like (\(\Delta=1\)) Hamiltonians.

from scpn_quantum_control.analysis.xxz_phase_diagram import (
    anisotropy_phase_diagram,
    PhaseDiagramResult,
)

anisotropy_phase_diagram(omega, K_topology, delta_range=None, k_range=None, *, max_dense_gib=None) → PhaseDiagramResult with: delta_values, k_c_values, gap_min_values, and scans.

Open Quantum Systems

quantum_mpemba — Quantum Mpemba Effect

Ordered states thermalize faster under amplitude damping — the quantum Mpemba effect in synchronization dynamics.

from scpn_quantum_control.analysis.quantum_mpemba import (
    mpemba_experiment,
    MpembaResult,
)

mpemba_experiment(omega, K, K_base=1.0, gamma=0.1, t_max=5.0, n_steps=50) → MpembaResult with: times, fidelity_ground, fidelity_plus (|+⟩^N), mpemba_detected (True if |+⟩ thermalizes faster).

lindblad_ness — Non-Equilibrium Steady State

Lindblad NESS under amplitude damping: the long-time limit that retains synchronization signatures.

from scpn_quantum_control.analysis.lindblad_ness import (
    ness_vs_coupling,
    NESSResult,
)

ness_vs_coupling(K, omega, gamma=0.1, K_base_range=None, n_K=15) → NESSResult with: K_values, R_ness (order parameter of NESS), purity_ness, entropy_ness.

Reservoir Computing

qrc_phase_detector — Exact QRC-Style Feature Map

The Kuramoto-XY Hamiltonian supplies exact dense ground-state Pauli features for a ridge-regression classifier. This is a deterministic small-system feature-map reference, not a scalable reservoir simulator.

from scpn_quantum_control.analysis.qrc_phase_detector import (
    qrc_phase_detection,
    QRCPhaseResult,
)

qrc_phase_detection(omega, K_topology, k_train, k_test, k_threshold, alpha=0.1, max_weight=2, *, max_dense_gib=None) → QRCPhaseResult with: accuracy, n_train, n_test, n_features, weights, and k_boundary_predicted.

Classical Simulations

monte_carlo_xy — Classical XY Monte Carlo

Metropolis Monte Carlo for the classical XY model. Uses the Rust engine (scpn_quantum_engine) when available; falls back to pure Python.

from scpn_quantum_control.analysis.monte_carlo_xy import (
    mc_simulate,
    MCResult,
)

graph_topology_scan — Coupling Graph Analysis

Network topology metrics (clustering, betweenness, modularity) of the \(K_{nm}\) matrix.

koopman — Koopman Linearisation

Koopman operator for the nonlinear Kuramoto dynamics — the BQP argument for quantum advantage.

build_koopman_generator_rust() now routes to the optional scpn_quantum_engine.koopman_generator kernel when that export is present and falls back to the validated NumPy generator otherwise. Set require_rust=True when a benchmark or release gate must prove that the native kernel, not the fallback, served the dense generator.

hamiltonian_learning — Recover \(K_{nm}\) from Measurements

Learn the coupling matrix from measurement data using compressed sensing.

hamiltonian_self_consistency — Self-Consistency Loop

Round-trip verification: \(K_{nm}\) → Hamiltonian → ground state → correlators → \(K_{nm}^{\mathrm{eff}}\).

from scpn_quantum_control.analysis.hamiltonian_self_consistency import (
    self_consistency_check,
    correlator_shot_noise,
    SelfConsistencyResult,
)

enaqt — Environment-Assisted Quantum Transport

Noise-enhanced transport optimisation — the Goldilocks zone where decoherence improves energy transfer (relevant to FMO photosynthetic complex benchmarks).

enaqt_scan(K, omega, gamma_range=None, t_evolve=1.0, n_steps=50, *, max_dense_gib=None) returns ENAQTResult with the optimal dephasing rate, coherent endpoint, large-noise endpoint, and enhancement ratio. The implementation is a dense small-system Lindblad diagnostic; max_dense_gib gates the Hamiltonian, density matrix, and work buffers before allocation.

entanglement_enhanced_sync — Entangled Initial-State Synchronization

simulate_sync_trajectory(K, omega, state_type, t_max=2.0, n_steps=20, *, max_dense_gib=None) evolves product, Bell-pair, GHZ, or W initial states under the dense exact Kuramoto-XY Hamiltonian and records the order-parameter trajectory. The dense matrix exponential and statevector workspaces are budgeted before Hamiltonian construction.

compare_all_initial_states(K, omega, t_max=2.0, n_steps=20, *, max_dense_gib=None) forwards the same dense budget to every initial-state trajectory before entanglement_advantage(...) compares final \(R\) and convergence speed.