quantrs2_device/photonic/

device.rs

//! Photonic quantum device implementation
//!
//! This module provides the core implementation of photonic quantum computing devices,
//! supporting continuous variable, gate-based, and measurement-based quantum computing.

use async_trait::async_trait;
use std::collections::HashMap;
use std::sync::{Arc, RwLock};
use std::time::{Duration, Instant};
use thiserror::Error;

use quantrs2_circuit::prelude::Circuit;
use quantrs2_core::qubit::QubitId;

use super::{
    validate_photonic_config, PhotonicCircuitResult, PhotonicClient, PhotonicDeviceConfig,
    PhotonicExecutionMetadata, PhotonicMeasurementData, PhotonicQuantumDevice, PhotonicSystemType,
};
use crate::{CircuitExecutor, CircuitResult, DeviceError, DeviceResult, QuantumDevice};
use scirs2_core::random::prelude::*;

/// Photonic quantum device implementation
#[derive(Debug, Clone)]
pub struct PhotonicQuantumDeviceImpl {
    /// Device identifier
    pub device_id: String,
    /// Client for hardware communication
    pub client: PhotonicClient,
    /// Device configuration
    pub config: PhotonicDeviceConfig,
    /// Device capabilities cache
    capabilities: Arc<RwLock<Option<PhotonicCapabilities>>>,
    /// Calibration data
    calibration: Arc<RwLock<PhotonicCalibrationData>>,
    /// Performance metrics
    metrics: Arc<RwLock<PhotonicPerformanceMetrics>>,
}

/// Photonic device capabilities
#[derive(Debug, Clone)]
pub struct PhotonicCapabilities {
    /// Supported system types
    pub supported_systems: Vec<PhotonicSystemType>,
    /// Maximum number of modes
    pub max_modes: usize,
    /// Maximum cutoff dimension
    pub max_cutoff: usize,
    /// Supported gate operations
    pub supported_gates: Vec<String>,
    /// Maximum squeezing parameter
    pub max_squeezing: f64,
    /// Minimum detection efficiency
    pub min_detection_efficiency: f64,
    /// Supported measurement types
    pub supported_measurements: Vec<String>,
    /// Hardware-specific features
    pub hardware_features: HashMap<String, bool>,
}

/// Photonic calibration data
#[derive(Debug, Clone)]
pub struct PhotonicCalibrationData {
    /// Mode-specific loss rates
    pub mode_losses: HashMap<usize, f64>,
    /// Beamsplitter transmittances
    pub beamsplitter_transmittances: HashMap<(usize, usize), f64>,
    /// Detector efficiencies
    pub detector_efficiencies: HashMap<usize, f64>,
    /// Phase shifter accuracies
    pub phase_accuracies: HashMap<usize, f64>,
    /// Squeezing parameters
    pub squeezing_calibration: HashMap<usize, (f64, f64)>,
    /// Cross-talk measurements
    pub crosstalk_matrix: HashMap<(usize, usize), f64>,
    /// Last calibration time
    pub last_calibration: Instant,
    /// Calibration validity duration
    pub validity_duration: Duration,
}

/// Performance metrics for photonic devices
#[derive(Debug, Clone)]
pub struct PhotonicPerformanceMetrics {
    /// Total circuits executed
    pub circuits_executed: u64,
    /// Average execution time
    pub avg_execution_time: Duration,
    /// Success rate
    pub success_rate: f64,
    /// Average fidelity
    pub avg_fidelity: f64,
    /// Mode utilization statistics
    pub mode_utilization: HashMap<usize, f64>,
    /// Gate operation counts
    pub gate_counts: HashMap<String, u64>,
    /// Error rates by operation type
    pub error_rates: HashMap<String, f64>,
}

impl PhotonicQuantumDeviceImpl {
    /// Create a new photonic quantum device
    pub async fn new(
        device_id: String,
        client: PhotonicClient,
        config: PhotonicDeviceConfig,
    ) -> DeviceResult<Self> {
        // Validate configuration
        validate_photonic_config(&config)?;

        let device = Self {
            device_id,
            client,
            config,
            capabilities: Arc::new(RwLock::new(None)),
            calibration: Arc::new(RwLock::new(PhotonicCalibrationData::default())),
            metrics: Arc::new(RwLock::new(PhotonicPerformanceMetrics::default())),
        };

        // Initialize device
        device.initialize().await?;

        Ok(device)
    }

    /// Initialize the device
    async fn initialize(&self) -> DeviceResult<()> {
        // Load capabilities
        let capabilities = self.load_capabilities().await?;
        *self.capabilities.write().unwrap() = Some(capabilities);

        // Load calibration data
        let calibration = self.load_calibration_data().await?;
        *self.calibration.write().unwrap() = calibration;

        Ok(())
    }

    /// Load device capabilities
    async fn load_capabilities(&self) -> DeviceResult<PhotonicCapabilities> {
        let mut supported_systems = vec![PhotonicSystemType::ContinuousVariable];

        // Check system-specific capabilities
        match self.config.system_type {
            PhotonicSystemType::ContinuousVariable => {
                supported_systems.push(PhotonicSystemType::ContinuousVariable);
            }
            PhotonicSystemType::GateBased => {
                supported_systems.push(PhotonicSystemType::GateBased);
            }
            PhotonicSystemType::MeasurementBased => {
                supported_systems.push(PhotonicSystemType::MeasurementBased);
            }
            PhotonicSystemType::Hybrid => {
                supported_systems.extend(&[
                    PhotonicSystemType::ContinuousVariable,
                    PhotonicSystemType::GateBased,
                    PhotonicSystemType::MeasurementBased,
                ]);
            }
        }

        let supported_gates = vec![
            "displacement".to_string(),
            "squeezing".to_string(),
            "two_mode_squeezing".to_string(),
            "beamsplitter".to_string(),
            "phase_rotation".to_string(),
            "kerr".to_string(),
            "cross_kerr".to_string(),
            "homodyne".to_string(),
            "heterodyne".to_string(),
        ];

        let supported_measurements = vec![
            "homodyne".to_string(),
            "heterodyne".to_string(),
            "photon_counting".to_string(),
            "quadrature".to_string(),
        ];

        let mut hardware_features = HashMap::new();
        hardware_features.insert("squeezed_light_source".to_string(), true);
        hardware_features.insert("programmable_beamsplitters".to_string(), true);
        hardware_features.insert("high_efficiency_detectors".to_string(), true);
        hardware_features.insert(
            "real_time_feedback".to_string(),
            self.config.hardware_acceleration,
        );

        Ok(PhotonicCapabilities {
            supported_systems,
            max_modes: self.config.mode_count * 2, // Allow for expansion
            max_cutoff: self.config.cutoff_dimension.unwrap_or(20),
            supported_gates,
            max_squeezing: 10.0, // dB
            min_detection_efficiency: 0.8,
            supported_measurements,
            hardware_features,
        })
    }

    /// Load calibration data
    async fn load_calibration_data(&self) -> DeviceResult<PhotonicCalibrationData> {
        let mut mode_losses = HashMap::new();
        let mut detector_efficiencies = HashMap::new();
        let mut phase_accuracies = HashMap::new();
        let mut squeezing_calibration = HashMap::new();

        // Initialize default calibration values
        for mode in 0..self.config.mode_count {
            mode_losses.insert(mode, self.config.loss_rate.unwrap_or(0.01));
            detector_efficiencies.insert(mode, self.config.detection_efficiency.unwrap_or(0.9));
            phase_accuracies.insert(mode, 0.001); // 0.1% accuracy
            squeezing_calibration.insert(mode, (0.0, 0.0)); // No squeezing by default
        }

        Ok(PhotonicCalibrationData {
            mode_losses,
            beamsplitter_transmittances: HashMap::new(),
            detector_efficiencies,
            phase_accuracies,
            squeezing_calibration,
            crosstalk_matrix: HashMap::new(),
            last_calibration: Instant::now(),
            validity_duration: Duration::from_secs(3600), // 1 hour
        })
    }

    /// Update performance metrics
    fn update_metrics(&self, execution_time: Duration, success: bool, fidelity: Option<f64>) {
        let mut metrics = self.metrics.write().unwrap();

        metrics.circuits_executed += 1;

        // Update average execution time
        let total_time =
            metrics.avg_execution_time * (metrics.circuits_executed - 1) as u32 + execution_time;
        metrics.avg_execution_time = total_time / metrics.circuits_executed as u32;

        // Update success rate
        let total_success = metrics.success_rate * (metrics.circuits_executed - 1) as f64
            + if success { 1.0 } else { 0.0 };
        metrics.success_rate = total_success / metrics.circuits_executed as f64;

        // Update average fidelity if provided
        if let Some(fid) = fidelity {
            let total_fidelity =
                metrics.avg_fidelity * (metrics.circuits_executed - 1) as f64 + fid;
            metrics.avg_fidelity = total_fidelity / metrics.circuits_executed as f64;
        }
    }

    /// Check if calibration is valid
    fn is_calibration_valid(&self) -> bool {
        let calibration = self.calibration.read().unwrap();
        calibration.last_calibration.elapsed() < calibration.validity_duration
    }

    /// Recalibrate device if needed
    async fn ensure_calibrated(&self) -> DeviceResult<()> {
        if !self.is_calibration_valid() {
            let new_calibration = self.load_calibration_data().await?;
            *self.calibration.write().unwrap() = new_calibration;
        }
        Ok(())
    }
}

#[async_trait]
impl QuantumDevice for PhotonicQuantumDeviceImpl {
    async fn is_available(&self) -> DeviceResult<bool> {
        // Check client connection and device status
        self.client.check_availability().await
    }

    async fn qubit_count(&self) -> DeviceResult<usize> {
        // For photonic systems, return mode count as effective qubit count
        Ok(self.config.mode_count)
    }

    async fn properties(&self) -> DeviceResult<HashMap<String, String>> {
        let mut properties = HashMap::new();

        properties.insert(
            "system_type".to_string(),
            format!("{:?}", self.config.system_type),
        );
        properties.insert("mode_count".to_string(), self.config.mode_count.to_string());

        if let Some(cutoff) = self.config.cutoff_dimension {
            properties.insert("cutoff_dimension".to_string(), cutoff.to_string());
        }

        if let Some(loss_rate) = self.config.loss_rate {
            properties.insert("loss_rate".to_string(), loss_rate.to_string());
        }

        if let Some(efficiency) = self.config.detection_efficiency {
            properties.insert("detection_efficiency".to_string(), efficiency.to_string());
        }

        // Add calibration status
        properties.insert(
            "calibration_valid".to_string(),
            self.is_calibration_valid().to_string(),
        );

        // Add performance metrics
        let metrics = self.metrics.read().unwrap();
        properties.insert(
            "circuits_executed".to_string(),
            metrics.circuits_executed.to_string(),
        );
        properties.insert("success_rate".to_string(), metrics.success_rate.to_string());
        properties.insert("avg_fidelity".to_string(), metrics.avg_fidelity.to_string());

        Ok(properties)
    }

    async fn is_simulator(&self) -> DeviceResult<bool> {
        // Check if this is a hardware device or simulator
        self.client.is_simulator().await
    }
}

#[async_trait]
impl CircuitExecutor for PhotonicQuantumDeviceImpl {
    async fn execute_circuit<const N: usize>(
        &self,
        circuit: &Circuit<N>,
        shots: usize,
    ) -> DeviceResult<CircuitResult> {
        let photonic_result = self.execute_photonic_circuit(circuit, shots, None).await?;
        Ok(photonic_result.circuit_result)
    }

    async fn execute_circuits<const N: usize>(
        &self,
        circuits: Vec<&Circuit<N>>,
        shots: usize,
    ) -> DeviceResult<Vec<CircuitResult>> {
        let mut results = Vec::new();

        for circuit in circuits {
            let result = self.execute_circuit(circuit, shots).await?;
            results.push(result);
        }

        Ok(results)
    }

    async fn can_execute_circuit<const N: usize>(
        &self,
        circuit: &Circuit<N>,
    ) -> DeviceResult<bool> {
        // Check if circuit is compatible with photonic system

        // Check mode count
        if N > self.config.mode_count {
            return Ok(false);
        }

        // Check gate compatibility
        // TODO: Implement gate validation based on photonic capabilities

        Ok(true)
    }

    async fn estimated_queue_time<const N: usize>(
        &self,
        _circuit: &Circuit<N>,
    ) -> DeviceResult<Duration> {
        // For photonic systems, execution is typically fast
        // Queue time depends on system load
        self.client.get_queue_time().await
    }
}

#[async_trait]
impl PhotonicQuantumDevice for PhotonicQuantumDeviceImpl {
    async fn system_type(&self) -> DeviceResult<PhotonicSystemType> {
        Ok(self.config.system_type)
    }

    async fn mode_count(&self) -> DeviceResult<usize> {
        Ok(self.config.mode_count)
    }

    async fn cutoff_dimension(&self) -> DeviceResult<Option<usize>> {
        Ok(self.config.cutoff_dimension)
    }

    async fn supports_cv_operations(&self) -> DeviceResult<bool> {
        let capabilities = self.capabilities.read().unwrap();
        if let Some(caps) = capabilities.as_ref() {
            Ok(caps
                .supported_systems
                .contains(&PhotonicSystemType::ContinuousVariable))
        } else {
            Ok(false)
        }
    }

    async fn supports_gate_based(&self) -> DeviceResult<bool> {
        let capabilities = self.capabilities.read().unwrap();
        if let Some(caps) = capabilities.as_ref() {
            Ok(caps
                .supported_systems
                .contains(&PhotonicSystemType::GateBased))
        } else {
            Ok(false)
        }
    }

    async fn supports_measurement_based(&self) -> DeviceResult<bool> {
        let capabilities = self.capabilities.read().unwrap();
        if let Some(caps) = capabilities.as_ref() {
            Ok(caps
                .supported_systems
                .contains(&PhotonicSystemType::MeasurementBased))
        } else {
            Ok(false)
        }
    }

    async fn quadrature_precision(&self) -> DeviceResult<f64> {
        // Return precision based on calibration data
        let calibration = self.calibration.read().unwrap();
        let avg_precision = calibration.phase_accuracies.values().copied().sum::<f64>()
            / calibration.phase_accuracies.len() as f64;
        Ok(avg_precision)
    }

    async fn detection_efficiency(&self) -> DeviceResult<f64> {
        Ok(self.config.detection_efficiency.unwrap_or(0.9))
    }

    async fn execute_photonic_circuit<const N: usize>(
        &self,
        circuit: &Circuit<N>,
        shots: usize,
        config: Option<PhotonicDeviceConfig>,
    ) -> DeviceResult<PhotonicCircuitResult> {
        let start_time = Instant::now();

        // Ensure device is calibrated
        self.ensure_calibrated().await?;

        // Use provided config or default
        let exec_config = config.unwrap_or_else(|| self.config.clone());

        // Create a simple circuit representation for API
        let circuit_str = format!(
            "{{\"gates\":{},\"qubits\":{}}}",
            circuit.gates().len(),
            circuit.num_qubits()
        );

        // Convert config to JSON
        let config_json = serde_json::to_value(&exec_config).map_err(|e| {
            DeviceError::CircuitConversion(format!("Failed to serialize config: {}", e))
        })?;
        let mut config_map = std::collections::HashMap::new();
        if let serde_json::Value::Object(map) = config_json {
            for (k, v) in map {
                config_map.insert(k, v);
            }
        }

        // Execute circuit using client
        let circuit_result = self
            .client
            .execute_photonic_circuit(&circuit_str, shots, &config_map)
            .await?;

        // Generate photonic-specific measurement data
        let photonic_data = self.generate_photonic_measurements(circuit, shots).await?;

        // Create execution metadata
        let execution_time = start_time.elapsed();
        let metadata = PhotonicExecutionMetadata {
            system_type: exec_config.system_type,
            modes_used: N.min(exec_config.mode_count),
            execution_time,
            measured_loss_rate: self.config.loss_rate,
            thermal_noise: self.config.thermal_photons,
            gate_sequence: vec![],         // TODO: Extract from circuit
            optimizations_applied: vec![], // TODO: Track optimizations
        };

        // Update performance metrics
        let fidelity = photonic_data.fidelities.get("overall").copied();
        self.update_metrics(execution_time, true, fidelity);

        // Convert PhotonicJobResult to CircuitResult
        let circuit_result_converted = CircuitResult {
            counts: circuit_result
                .results
                .get("counts")
                .and_then(|v| serde_json::from_value(v.clone()).ok())
                .unwrap_or_else(|| {
                    let mut counts = HashMap::new();
                    counts.insert("0".repeat(circuit.num_qubits()), shots);
                    counts
                }),
            shots: circuit_result.shots_completed,
            metadata: circuit_result.metadata,
        };

        Ok(PhotonicCircuitResult {
            circuit_result: circuit_result_converted,
            photonic_data,
            execution_metadata: metadata,
        })
    }

    async fn measure_quadratures(
        &self,
        modes: &[usize],
        angles: &[f64],
    ) -> DeviceResult<Vec<(f64, f64)>> {
        self.client
            .measure_quadratures(&self.device_id, modes, angles)
            .await
    }

    async fn measure_photon_numbers(&self, modes: &[usize]) -> DeviceResult<Vec<usize>> {
        self.client
            .measure_photon_numbers(&self.device_id, modes)
            .await
    }

    async fn homodyne_detection(
        &self,
        mode: usize,
        phase: f64,
        shots: usize,
    ) -> DeviceResult<Vec<f64>> {
        self.client
            .homodyne_detection(&self.device_id, mode, phase, shots)
            .await
    }

    async fn heterodyne_detection(
        &self,
        mode: usize,
        shots: usize,
    ) -> DeviceResult<Vec<(f64, f64)>> {
        self.client
            .heterodyne_detection(&self.device_id, mode, shots)
            .await
    }

    async fn calculate_correlations(
        &self,
        modes: &[(usize, usize)],
        correlation_type: &str,
    ) -> DeviceResult<HashMap<String, f64>> {
        self.client
            .calculate_correlations(modes, correlation_type)
            .await
    }

    async fn estimate_fidelity(
        &self,
        target_state: &str,
        measurement_data: &PhotonicMeasurementData,
    ) -> DeviceResult<f64> {
        self.client
            .estimate_fidelity(target_state, measurement_data)
            .await
    }
}

impl PhotonicQuantumDeviceImpl {
    /// Generate photonic measurement data from circuit execution
    async fn generate_photonic_measurements<const N: usize>(
        &self,
        _circuit: &Circuit<N>,
        shots: usize,
    ) -> DeviceResult<PhotonicMeasurementData> {
        // Simulate photonic measurements
        let mut quadratures = Vec::new();
        let mut photon_numbers = Vec::new();
        let mut homodyne_results = Vec::new();
        let mut heterodyne_results = Vec::new();
        let mut correlations = HashMap::new();
        let mut fidelities = HashMap::new();

        // Generate mock measurements for testing
        for _ in 0..shots.min(100) {
            // Limit for demonstration
            // Random quadrature values
            quadratures.push((thread_rng().gen::<f64>() - 0.5, thread_rng().gen::<f64>() - 0.5));

            // Random photon numbers (small numbers typical for CV systems)
            photon_numbers.push((thread_rng().gen::<f64>() * 5.0) as usize);

            // Homodyne detection results
            homodyne_results.push(thread_rng().gen::<f64>() - 0.5);

            // Heterodyne detection results
            heterodyne_results.push((thread_rng().gen::<f64>() - 0.5, thread_rng().gen::<f64>() - 0.5));
        }

        // Calculate correlations
        correlations.insert("g2".to_string(), 1.0 + thread_rng().gen::<f64>() * 0.1);
        correlations.insert("visibility".to_string(), 0.9 + thread_rng().gen::<f64>() * 0.09);

        // Estimate fidelities
        fidelities.insert("overall".to_string(), 0.95 + thread_rng().gen::<f64>() * 0.04);
        fidelities.insert(
            "gate_fidelity".to_string(),
            self.config.gate_fidelity.unwrap_or(0.99),
        );

        Ok(PhotonicMeasurementData {
            quadratures,
            photon_numbers,
            homodyne_results,
            heterodyne_results,
            correlations,
            fidelities,
        })
    }
}

impl Default for PhotonicCalibrationData {
    fn default() -> Self {
        Self {
            mode_losses: HashMap::new(),
            beamsplitter_transmittances: HashMap::new(),
            detector_efficiencies: HashMap::new(),
            phase_accuracies: HashMap::new(),
            squeezing_calibration: HashMap::new(),
            crosstalk_matrix: HashMap::new(),
            last_calibration: Instant::now(),
            validity_duration: Duration::from_secs(3600),
        }
    }
}

impl Default for PhotonicPerformanceMetrics {
    fn default() -> Self {
        Self {
            circuits_executed: 0,
            avg_execution_time: Duration::from_millis(0),
            success_rate: 0.0,
            avg_fidelity: 0.0,
            mode_utilization: HashMap::new(),
            gate_counts: HashMap::new(),
            error_rates: HashMap::new(),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::photonic::{PhotonicClient, PhotonicConfig};

    #[tokio::test]
    async fn test_photonic_device_creation() {
        let client = PhotonicClient::new(
            "http://localhost:8080".to_string(),
            "test_token".to_string(),
        )
        .unwrap();
        let config = PhotonicDeviceConfig::default();

        let device =
            PhotonicQuantumDeviceImpl::new("test_device".to_string(), client, config).await;
        assert!(device.is_ok());
    }

    #[tokio::test]
    async fn test_device_properties() {
        let client = PhotonicClient::new(
            "http://localhost:8080".to_string(),
            "test_token".to_string(),
        )
        .unwrap();
        let config = PhotonicDeviceConfig::default();
        let device = PhotonicQuantumDeviceImpl::new("test_device".to_string(), client, config)
            .await
            .unwrap();

        let properties = device.properties().await.unwrap();
        assert!(properties.contains_key("system_type"));
        assert!(properties.contains_key("mode_count"));
    }

    #[tokio::test]
    async fn test_capabilities() {
        let client = PhotonicClient::new(
            "http://localhost:8080".to_string(),
            "test_token".to_string(),
        )
        .unwrap();
        let config = PhotonicDeviceConfig::default();
        let device = PhotonicQuantumDeviceImpl::new("test_device".to_string(), client, config)
            .await
            .unwrap();

        assert!(device.supports_cv_operations().await.unwrap());
        assert_eq!(device.mode_count().await.unwrap(), 8);
    }
}