oxirs_core/quantum/

mod.rs

//! Quantum-Inspired Computing Module
//!
//! This module implements quantum-inspired algorithms for RDF processing,
//! leveraging quantum computing concepts for enhanced graph operations
//! and advanced optimization techniques.

#![allow(dead_code)]

use crate::error::OxirsResult;
use crate::model::Triple;
use scirs2_core::ndarray_ext::{Array1, Array2};
use std::collections::HashMap;
use std::f64::consts::PI;
use std::sync::Arc;

/// Quantum state representation for RDF terms
#[derive(Debug, Clone)]
pub struct QuantumState {
    /// Amplitude vector in quantum superposition
    pub amplitudes: Array1<f64>,
    /// Phase information for quantum interference
    pub phases: Array1<f64>,
    /// Entanglement connections to other states
    pub entangled_states: Vec<QuantumStateRef>,
    /// Coherence time before decoherence
    pub coherence_time: std::time::Duration,
}

/// Reference to a quantum state for entanglement
pub type QuantumStateRef = Arc<QuantumState>;

/// Quantum-inspired RDF triple with superposition capabilities
#[derive(Debug, Clone)]
pub struct QuantumTriple {
    /// Classical RDF triple
    pub classical_triple: Triple,
    /// Quantum state representation
    pub quantum_state: QuantumState,
    /// Probability of existence in current measurement
    pub existence_probability: f64,
    /// Entangled triples for quantum correlations
    pub entangled_triples: Vec<Arc<QuantumTriple>>,
}

/// Quantum graph processor for advanced RDF operations
pub struct QuantumGraphProcessor {
    /// Quantum state registry
    states: HashMap<String, QuantumStateRef>,
    /// Quantum gate operations
    gates: QuantumGateSet,
    /// Measurement strategy
    measurement_strategy: MeasurementStrategy,
    /// Decoherence handler
    decoherence_handler: DecoherenceHandler,
}

/// Set of quantum gates for graph operations
#[derive(Debug, Clone)]
pub struct QuantumGateSet {
    /// Hadamard gate for superposition creation
    pub hadamard: Array2<f64>,
    /// Pauli gates for state manipulation
    pub pauli_x: Array2<f64>,
    pub pauli_y: Array2<f64>,
    pub pauli_z: Array2<f64>,
    /// CNOT gate for entanglement
    pub cnot: Array2<f64>,
    /// Custom RDF gates
    pub rdf_similarity: Array2<f64>,
    pub rdf_hierarchy: Array2<f64>,
}

/// Strategy for quantum measurement
#[derive(Debug, Clone)]
pub enum MeasurementStrategy {
    /// Collapse to most probable state
    MaxProbability,
    /// Weighted random measurement
    WeightedRandom,
    /// Partial measurement preserving superposition
    Partial(f64),
    /// Adaptive measurement based on query context
    Adaptive,
}

/// Handler for quantum decoherence
pub struct DecoherenceHandler {
    /// Decoherence rate parameters
    decoherence_rate: f64,
    /// Error correction strategies
    error_correction: QuantumErrorCorrection,
    /// Coherence preservation techniques
    coherence_preservation: CoherencePreservation,
}

/// Quantum error correction for data integrity
pub struct QuantumErrorCorrection {
    /// Syndrome calculation for error detection
    syndrome_calculator: SyndromeCalculator,
    /// Error detection algorithms
    error_detector: ErrorDetector,
    /// Correction strategies
    correction_strategy: CorrectionStrategy,
    /// Logical qubit mapping
    logical_qubits: Vec<LogicalQubit>,
}

/// Syndrome calculator for error detection
pub struct SyndromeCalculator {
    /// Stabilizer generators
    stabilizers: Vec<Array1<i8>>,
    /// Measurement patterns
    measurement_patterns: Vec<MeasurementPattern>,
}

/// Error detector implementation
pub struct ErrorDetector {
    /// Error detection thresholds
    thresholds: HashMap<String, f64>,
    /// Pattern matching for error identification
    pattern_matcher: ErrorPatternMatcher,
}

/// Error correction strategy
#[derive(Debug, Clone)]
pub enum CorrectionStrategy {
    /// Surface code correction
    SurfaceCode,
    /// Repetition code
    RepetitionCode,
    /// Shor code for comprehensive error correction
    ShorCode,
    /// Custom RDF-optimized correction
    RdfOptimized,
}

/// Logical qubit representation
pub struct LogicalQubit {
    /// Physical qubits comprising the logical qubit
    physical_qubits: Vec<usize>,
    /// Error correction code
    code: CorrectionStrategy,
    /// State vector
    state: QuantumState,
}

/// Measurement pattern for syndrome calculation
pub struct MeasurementPattern {
    /// Qubits to measure
    qubits: Vec<usize>,
    /// Measurement basis
    basis: MeasurementBasis,
    /// Expected outcomes
    expected_outcomes: Vec<i8>,
}

/// Measurement basis for quantum measurements
#[derive(Debug, Clone)]
pub enum MeasurementBasis {
    /// Computational basis (Z)
    Computational,
    /// Diagonal basis (X)
    Diagonal,
    /// Circular basis (Y)
    Circular,
    /// Custom basis for RDF operations
    RdfBasis(Array2<f64>),
}

/// Error pattern matcher for quantum errors
pub struct ErrorPatternMatcher {
    /// Known error patterns
    patterns: HashMap<Vec<i8>, ErrorType>,
    /// Pattern recognition algorithms
    recognition_algorithm: PatternRecognitionAlgorithm,
}

/// Types of quantum errors
#[derive(Debug, Clone)]
pub enum ErrorType {
    /// Bit flip error
    BitFlip,
    /// Phase flip error
    PhaseFlip,
    /// Combined bit and phase flip
    Combined,
    /// Decoherence-induced error
    Decoherence,
    /// Custom RDF processing error
    RdfProcessing(String),
}

/// Pattern recognition algorithms for error detection
#[derive(Debug, Clone)]
pub enum PatternRecognitionAlgorithm {
    /// Simple pattern matching
    Simple,
    /// Machine learning-based recognition
    MachineLearning,
    /// Quantum-inspired pattern recognition
    QuantumInspired,
}

/// Coherence preservation techniques
pub struct CoherencePreservation {
    /// Dynamical decoupling sequences
    decoupling_sequences: Vec<DecouplingSequence>,
    /// Optimal control protocols
    control_protocols: Vec<ControlProtocol>,
    /// Environmental isolation methods
    isolation_methods: Vec<IsolationMethod>,
}

/// Dynamical decoupling sequence
pub struct DecouplingSequence {
    /// Pulse sequence
    pulses: Vec<QuantumPulse>,
    /// Timing intervals
    intervals: Vec<f64>,
    /// Effectiveness rating
    effectiveness: f64,
}

/// Quantum pulse for control
pub struct QuantumPulse {
    /// Pulse amplitude
    amplitude: f64,
    /// Pulse phase
    phase: f64,
    /// Pulse duration
    duration: f64,
    /// Target qubits
    targets: Vec<usize>,
}

/// Control protocol for coherence preservation
pub struct ControlProtocol {
    /// Protocol name
    name: String,
    /// Control parameters
    parameters: HashMap<String, f64>,
    /// Implementation function
    implementation: fn(&QuantumState) -> OxirsResult<QuantumState>,
}

/// Environmental isolation method
#[derive(Debug, Clone)]
pub enum IsolationMethod {
    /// Magnetic shielding
    MagneticShielding(f64),
    /// Temperature control
    TemperatureControl(f64),
    /// Vibration isolation
    VibrationIsolation(f64),
    /// Electromagnetic isolation
    ElectromagneticIsolation(f64),
}

impl Default for QuantumGraphProcessor {
    fn default() -> Self {
        Self::new()
    }
}

impl QuantumGraphProcessor {
    /// Create a new quantum graph processor
    pub fn new() -> Self {
        Self {
            states: HashMap::new(),
            gates: QuantumGateSet::new(),
            measurement_strategy: MeasurementStrategy::Adaptive,
            decoherence_handler: DecoherenceHandler::new(),
        }
    }

    /// Create quantum superposition of RDF triples
    pub fn create_superposition(&mut self, triples: Vec<Triple>) -> OxirsResult<QuantumState> {
        let n = triples.len();
        let mut amplitudes = Array1::zeros(n);
        let mut phases = Array1::zeros(n);

        // Initialize uniform superposition
        let amplitude = 1.0 / (n as f64).sqrt();
        for i in 0..n {
            amplitudes[i] = amplitude;
            phases[i] = 0.0;
        }

        Ok(QuantumState {
            amplitudes,
            phases,
            entangled_states: Vec::new(),
            coherence_time: std::time::Duration::from_secs(1),
        })
    }

    /// Apply quantum gate to state
    pub fn apply_gate(
        &self,
        state: &QuantumState,
        gate: &Array2<f64>,
    ) -> OxirsResult<QuantumState> {
        let mut new_amplitudes = Array1::zeros(state.amplitudes.len());

        // Apply quantum gate transformation
        for i in 0..state.amplitudes.len() {
            for j in 0..state.amplitudes.len() {
                new_amplitudes[i] += gate[[i, j]] * state.amplitudes[j];
            }
        }

        Ok(QuantumState {
            amplitudes: new_amplitudes,
            phases: state.phases.clone(),
            entangled_states: state.entangled_states.clone(),
            coherence_time: state.coherence_time,
        })
    }

    /// Measure quantum state
    pub fn measure(&self, state: &QuantumState) -> OxirsResult<usize> {
        match self.measurement_strategy {
            MeasurementStrategy::MaxProbability => {
                let probabilities = state.amplitudes.mapv(|a| a * a);
                let max_idx = probabilities
                    .iter()
                    .enumerate()
                    .max_by(|a, b| a.1.partial_cmp(b.1).unwrap_or(std::cmp::Ordering::Equal))
                    .map(|(i, _)| i)
                    .unwrap_or(0);
                Ok(max_idx)
            }
            MeasurementStrategy::WeightedRandom => {
                #[allow(unused_imports)]
                use scirs2_core::random::{Random, Rng};
                let mut random = Random::default();
                let probabilities = state.amplitudes.mapv(|a| a * a);
                let total: f64 = probabilities.sum();
                let r: f64 = random.gen_range(0.0..total);

                let mut cumulative = 0.0;
                for (i, &prob) in probabilities.iter().enumerate() {
                    cumulative += prob;
                    if r <= cumulative {
                        return Ok(i);
                    }
                }
                Ok(0)
            }
            _ => Ok(0), // Simplified for other strategies
        }
    }

    /// Create entanglement between quantum states
    pub fn entangle(&mut self, state1_id: &str, state2_id: &str) -> OxirsResult<()> {
        if let (Some(_state1), Some(_state2)) =
            (self.states.get(state1_id), self.states.get(state2_id))
        {
            // Create entanglement - simplified implementation
            // In a full implementation, this would involve tensor products
            // and Bell state creation
            Ok(())
        } else {
            Err(crate::error::OxirsError::QuantumError(
                "States not found for entanglement".to_string(),
            ))
        }
    }

    /// Quantum interference for query optimization
    pub fn quantum_interference(&self, states: Vec<&QuantumState>) -> OxirsResult<QuantumState> {
        if states.is_empty() {
            return Err(crate::error::OxirsError::QuantumError(
                "No states for interference".to_string(),
            ));
        }

        let n = states[0].amplitudes.len();
        let mut result_amplitudes = Array1::zeros(n);
        let mut result_phases = Array1::zeros(n);

        // Quantum interference calculation
        for state in states {
            for i in 0..n {
                let amplitude = state.amplitudes[i];
                let phase = state.phases[i];
                result_amplitudes[i] += amplitude * phase.cos();
                result_phases[i] += amplitude * phase.sin();
            }
        }

        // Normalize
        let norm = result_amplitudes.mapv(|a: f64| a * a).sum().sqrt();
        if norm > 0.0 {
            result_amplitudes.mapv_inplace(|a| a / norm);
        }

        Ok(QuantumState {
            amplitudes: result_amplitudes,
            phases: result_phases,
            entangled_states: Vec::new(),
            coherence_time: std::time::Duration::from_secs(1),
        })
    }
}

impl Default for QuantumGateSet {
    fn default() -> Self {
        Self::new()
    }
}

impl QuantumGateSet {
    /// Create standard quantum gate set
    pub fn new() -> Self {
        // Hadamard gate
        let hadamard = Array2::from_shape_vec(
            (2, 2),
            vec![
                1.0 / 2.0_f64.sqrt(),
                1.0 / 2.0_f64.sqrt(),
                1.0 / 2.0_f64.sqrt(),
                -1.0 / 2.0_f64.sqrt(),
            ],
        )
        .expect("Hadamard gate shape and vector length match");

        // Pauli gates
        let pauli_x = Array2::from_shape_vec((2, 2), vec![0.0, 1.0, 1.0, 0.0])
            .expect("Pauli X gate shape and vector length match");
        let pauli_y = Array2::from_shape_vec((2, 2), vec![0.0, -1.0, 1.0, 0.0])
            .expect("Pauli Y gate shape and vector length match");
        let pauli_z = Array2::from_shape_vec((2, 2), vec![1.0, 0.0, 0.0, -1.0])
            .expect("Pauli Z gate shape and vector length match");

        // CNOT gate (simplified 2x2 representation)
        let cnot = Array2::from_shape_vec((2, 2), vec![1.0, 0.0, 0.0, 1.0])
            .expect("CNOT gate shape and vector length match");

        // Custom RDF gates
        let rdf_similarity = Array2::from_shape_vec((2, 2), vec![0.8, 0.6, 0.6, 0.8])
            .expect("RDF similarity gate shape and vector length match");

        let rdf_hierarchy = Array2::from_shape_vec((2, 2), vec![1.0, 0.5, 0.0, 1.0])
            .expect("RDF hierarchy gate shape and vector length match");

        Self {
            hadamard,
            pauli_x,
            pauli_y,
            pauli_z,
            cnot,
            rdf_similarity,
            rdf_hierarchy,
        }
    }
}

impl Default for DecoherenceHandler {
    fn default() -> Self {
        Self::new()
    }
}

impl DecoherenceHandler {
    /// Create new decoherence handler
    pub fn new() -> Self {
        Self {
            decoherence_rate: 0.01,
            error_correction: QuantumErrorCorrection::new(),
            coherence_preservation: CoherencePreservation::new(),
        }
    }

    /// Handle decoherence in quantum state
    pub fn handle_decoherence(
        &self,
        state: &QuantumState,
        elapsed: std::time::Duration,
    ) -> OxirsResult<QuantumState> {
        let decoherence_factor = (-self.decoherence_rate * elapsed.as_secs_f64()).exp();

        let mut new_amplitudes = state.amplitudes.clone();
        new_amplitudes.mapv_inplace(|a| a * decoherence_factor);

        Ok(QuantumState {
            amplitudes: new_amplitudes,
            phases: state.phases.clone(),
            entangled_states: state.entangled_states.clone(),
            coherence_time: state.coherence_time,
        })
    }
}

impl Default for QuantumErrorCorrection {
    fn default() -> Self {
        Self::new()
    }
}

impl QuantumErrorCorrection {
    /// Create new quantum error correction system
    pub fn new() -> Self {
        Self {
            syndrome_calculator: SyndromeCalculator::new(),
            error_detector: ErrorDetector::new(),
            correction_strategy: CorrectionStrategy::SurfaceCode,
            logical_qubits: Vec::new(),
        }
    }

    /// Detect and correct quantum errors
    pub fn detect_and_correct(&self, state: &QuantumState) -> OxirsResult<QuantumState> {
        // Simplified error correction - in practice this would be much more complex
        let mut corrected_state = state.clone();

        // Apply error detection
        let syndrome = self.syndrome_calculator.calculate_syndrome(state)?;

        // Detect error type
        if let Some(error_type) = self.error_detector.detect_error(&syndrome)? {
            // Apply correction based on error type
            corrected_state = self.apply_correction(corrected_state, error_type)?;
        }

        Ok(corrected_state)
    }

    /// Apply correction for detected error
    fn apply_correction(
        &self,
        mut state: QuantumState,
        error_type: ErrorType,
    ) -> OxirsResult<QuantumState> {
        match error_type {
            ErrorType::BitFlip => {
                // Apply bit flip correction
                state.amplitudes.mapv_inplace(|a| -a);
            }
            ErrorType::PhaseFlip => {
                // Apply phase flip correction
                state.phases.mapv_inplace(|p| p + PI);
            }
            ErrorType::Combined => {
                // Apply combined correction
                state.amplitudes.mapv_inplace(|a| -a);
                state.phases.mapv_inplace(|p| p + PI);
            }
            ErrorType::Decoherence => {
                // Apply decoherence correction (re-normalization)
                let norm = state.amplitudes.mapv(|a| a * a).sum().sqrt();
                if norm > 0.0 {
                    state.amplitudes.mapv_inplace(|a| a / norm);
                }
            }
            ErrorType::RdfProcessing(_) => {
                // Custom RDF processing error correction
                // Implementation would depend on specific error
            }
        }
        Ok(state)
    }
}

impl Default for SyndromeCalculator {
    fn default() -> Self {
        Self::new()
    }
}

impl SyndromeCalculator {
    /// Create new syndrome calculator
    pub fn new() -> Self {
        Self {
            stabilizers: Vec::new(),
            measurement_patterns: Vec::new(),
        }
    }

    /// Calculate syndrome for error detection
    pub fn calculate_syndrome(&self, state: &QuantumState) -> OxirsResult<Vec<i8>> {
        let mut syndrome = Vec::new();

        // Simplified syndrome calculation
        for stabilizer in &self.stabilizers {
            let measurement = self.measure_stabilizer(state, stabilizer)?;
            syndrome.push(measurement);
        }

        Ok(syndrome)
    }

    /// Measure stabilizer generator
    fn measure_stabilizer(&self, state: &QuantumState, stabilizer: &Array1<i8>) -> OxirsResult<i8> {
        // Simplified stabilizer measurement
        let mut result = 0.0;
        for (i, &coeff) in stabilizer.iter().enumerate() {
            if i < state.amplitudes.len() {
                result += coeff as f64 * state.amplitudes[i] * state.amplitudes[i];
            }
        }
        Ok(if result > 0.5 { 1 } else { 0 })
    }
}

impl Default for ErrorDetector {
    fn default() -> Self {
        Self::new()
    }
}

impl ErrorDetector {
    /// Create new error detector
    pub fn new() -> Self {
        Self {
            thresholds: HashMap::new(),
            pattern_matcher: ErrorPatternMatcher::new(),
        }
    }

    /// Detect error from syndrome
    pub fn detect_error(&self, syndrome: &[i8]) -> OxirsResult<Option<ErrorType>> {
        self.pattern_matcher.match_pattern(syndrome)
    }
}

impl Default for ErrorPatternMatcher {
    fn default() -> Self {
        Self::new()
    }
}

impl ErrorPatternMatcher {
    /// Create new error pattern matcher
    pub fn new() -> Self {
        let mut patterns = HashMap::new();

        // Define known error patterns
        patterns.insert(vec![1, 0, 0], ErrorType::BitFlip);
        patterns.insert(vec![0, 1, 0], ErrorType::PhaseFlip);
        patterns.insert(vec![1, 1, 0], ErrorType::Combined);
        patterns.insert(vec![0, 0, 1], ErrorType::Decoherence);

        Self {
            patterns,
            recognition_algorithm: PatternRecognitionAlgorithm::Simple,
        }
    }

    /// Match error pattern
    pub fn match_pattern(&self, syndrome: &[i8]) -> OxirsResult<Option<ErrorType>> {
        if let Some(error_type) = self.patterns.get(syndrome) {
            Ok(Some(error_type.clone()))
        } else {
            Ok(None)
        }
    }
}

impl Default for CoherencePreservation {
    fn default() -> Self {
        Self::new()
    }
}

impl CoherencePreservation {
    /// Create new coherence preservation system
    pub fn new() -> Self {
        Self {
            decoupling_sequences: Vec::new(),
            control_protocols: Vec::new(),
            isolation_methods: Vec::new(),
        }
    }

    /// Apply coherence preservation techniques
    pub fn preserve_coherence(&self, state: &QuantumState) -> OxirsResult<QuantumState> {
        let mut preserved_state = state.clone();

        // Apply dynamical decoupling
        for sequence in &self.decoupling_sequences {
            preserved_state = sequence.apply(&preserved_state)?;
        }

        // Apply control protocols
        for protocol in &self.control_protocols {
            preserved_state = (protocol.implementation)(&preserved_state)?;
        }

        Ok(preserved_state)
    }
}

impl DecouplingSequence {
    /// Apply decoupling sequence to state
    pub fn apply(&self, state: &QuantumState) -> OxirsResult<QuantumState> {
        let mut evolved_state = state.clone();

        // Apply pulse sequence
        for pulse in &self.pulses {
            evolved_state = pulse.apply(&evolved_state)?;
        }

        Ok(evolved_state)
    }
}

impl QuantumPulse {
    /// Apply quantum pulse to state
    pub fn apply(&self, state: &QuantumState) -> OxirsResult<QuantumState> {
        let mut pulsed_state = state.clone();

        // Apply pulse transformation (simplified)
        for &target in &self.targets {
            if target < pulsed_state.amplitudes.len() {
                pulsed_state.amplitudes[target] *= self.amplitude;
                pulsed_state.phases[target] += self.phase;
            }
        }

        Ok(pulsed_state)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::NamedNode;

    #[test]
    fn test_quantum_processor_creation() {
        let processor = QuantumGraphProcessor::new();
        assert_eq!(processor.states.len(), 0);
    }

    #[test]
    fn test_superposition_creation() {
        let mut processor = QuantumGraphProcessor::new();
        let triples = vec![Triple::new(
            NamedNode::new("http://example.org/s1").expect("valid IRI"),
            NamedNode::new("http://example.org/p1").expect("valid IRI"),
            NamedNode::new("http://example.org/o1").expect("valid IRI"),
        )];

        let result = processor.create_superposition(triples);
        assert!(result.is_ok());
    }

    #[test]
    fn test_quantum_gate_application() {
        let processor = QuantumGraphProcessor::new();
        let state = QuantumState {
            amplitudes: Array1::from_vec(vec![1.0, 0.0]),
            phases: Array1::from_vec(vec![0.0, 0.0]),
            entangled_states: Vec::new(),
            coherence_time: std::time::Duration::from_secs(1),
        };

        let result = processor.apply_gate(&state, &processor.gates.hadamard);
        assert!(result.is_ok());
    }

    #[test]
    fn test_measurement() {
        let processor = QuantumGraphProcessor::new();
        let state = QuantumState {
            amplitudes: Array1::from_vec(vec![0.7, 0.3]),
            phases: Array1::from_vec(vec![0.0, 0.0]),
            entangled_states: Vec::new(),
            coherence_time: std::time::Duration::from_secs(1),
        };

        let result = processor.measure(&state);
        assert!(result.is_ok());
    }

    #[test]
    fn test_quantum_error_correction() {
        let qec = QuantumErrorCorrection::new();
        let state = QuantumState {
            amplitudes: Array1::from_vec(vec![0.6, 0.8]),
            phases: Array1::from_vec(vec![0.0, 0.0]),
            entangled_states: Vec::new(),
            coherence_time: std::time::Duration::from_secs(1),
        };

        let result = qec.detect_and_correct(&state);
        assert!(result.is_ok());
    }
}