quantrs2_device/topological/

device.rs

//! Device implementation for topological quantum computers
//!
//! This module provides the device interface for topological quantum computers,
//! integrating anyon manipulation, braiding, and fusion operations.

use super::{
    anyons::AnyonFactory, braiding::BraidingOperationManager, fusion::FusionOperationExecutor,
    Anyon, BraidingDirection, FusionRuleSet, NonAbelianAnyonType, TopologicalCapabilities,
    TopologicalCharge, TopologicalDevice, TopologicalError, TopologicalQubit, TopologicalResult,
    TopologicalSystemType,
};
use crate::{Circuit, CircuitExecutor, CircuitResult, DeviceError, DeviceResult, QuantumDevice};
use scirs2_core::random::prelude::*;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::time::Duration;

/// Enhanced topological quantum device with full anyon manipulation
pub struct EnhancedTopologicalDevice {
    /// Core topological device
    pub core_device: TopologicalDevice,
    /// Anyon factory for creating anyons
    pub anyon_factory: AnyonFactory,
    /// Braiding operation manager
    pub braiding_manager: BraidingOperationManager,
    /// Fusion operation executor
    pub fusion_executor: FusionOperationExecutor,
    /// Device configuration
    pub config: TopologicalDeviceConfig,
    /// Connection status
    pub is_connected: bool,
}

/// Configuration for topological quantum devices
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TopologicalDeviceConfig {
    /// Maximum execution time for operations
    pub max_execution_time: Duration,
    /// Temperature of the system (mK)
    pub operating_temperature: f64,
    /// Topological gap energy scale (K)
    pub topological_gap: f64,
    /// Coherence length (μm)
    pub coherence_length: f64,
    /// Anyon manipulation precision
    pub manipulation_precision: f64,
    /// Braiding fidelity
    pub braiding_fidelity: f64,
    /// Fusion fidelity
    pub fusion_fidelity: f64,
    /// Measurement fidelity
    pub measurement_fidelity: f64,
    /// Enable advanced error correction
    pub enable_error_correction: bool,
    /// Hardware-specific parameters
    pub hardware_params: HashMap<String, String>,
}

impl Default for TopologicalDeviceConfig {
    fn default() -> Self {
        Self {
            max_execution_time: Duration::from_secs(300),
            operating_temperature: 0.01, // 10 mK
            topological_gap: 1.0,        // 1 K
            coherence_length: 100.0,     // 100 μm
            manipulation_precision: 0.99,
            braiding_fidelity: 0.9999,
            fusion_fidelity: 0.999,
            measurement_fidelity: 0.999,
            enable_error_correction: true,
            hardware_params: HashMap::new(),
        }
    }
}

impl EnhancedTopologicalDevice {
    /// Create a new enhanced topological device
    pub fn new(
        system_type: TopologicalSystemType,
        fusion_rules: FusionRuleSet,
        capabilities: TopologicalCapabilities,
        config: TopologicalDeviceConfig,
    ) -> TopologicalResult<Self> {
        let core_device =
            TopologicalDevice::new(system_type.clone(), fusion_rules.clone(), capabilities);

        let anyon_type = match system_type {
            TopologicalSystemType::NonAbelian { anyon_type, .. } => anyon_type,
            _ => NonAbelianAnyonType::Fibonacci, // Default
        };

        let anyon_factory = AnyonFactory::new(anyon_type.clone(), fusion_rules.clone());
        let braiding_manager = BraidingOperationManager::new(anyon_type.clone());
        let fusion_executor = FusionOperationExecutor::new(anyon_type, fusion_rules);

        Ok(Self {
            core_device,
            anyon_factory,
            braiding_manager,
            fusion_executor,
            config,
            is_connected: false,
        })
    }

    /// Connect to the topological quantum hardware
    pub async fn connect(&mut self) -> TopologicalResult<()> {
        // Simulate hardware connection
        tokio::time::sleep(Duration::from_millis(100)).await;

        // Verify system integrity
        self.verify_system_integrity().await?;

        self.is_connected = true;
        Ok(())
    }

    /// Disconnect from the hardware
    pub async fn disconnect(&mut self) -> TopologicalResult<()> {
        self.is_connected = false;
        Ok(())
    }

    /// Verify system integrity
    async fn verify_system_integrity(&self) -> TopologicalResult<()> {
        // Check topological gap
        if self.config.topological_gap < 0.1 {
            return Err(TopologicalError::InvalidWorldline(
                "Topological gap too small for reliable operation".to_string(),
            ));
        }

        // Check coherence length
        if self.config.coherence_length < 10.0 {
            return Err(TopologicalError::InvalidWorldline(
                "Coherence length too small".to_string(),
            ));
        }

        Ok(())
    }

    /// Initialize topological qubits
    pub async fn initialize_topological_qubits(
        &mut self,
        num_qubits: usize,
    ) -> TopologicalResult<Vec<usize>> {
        let mut qubit_ids = Vec::new();

        for _ in 0..num_qubits {
            // Create anyon pairs for each qubit
            let charge = match self.core_device.system_type {
                TopologicalSystemType::NonAbelian {
                    anyon_type: NonAbelianAnyonType::Fibonacci,
                    ..
                } => TopologicalCharge::fibonacci_tau(),
                TopologicalSystemType::NonAbelian {
                    anyon_type: NonAbelianAnyonType::Ising,
                    ..
                } => TopologicalCharge::ising_sigma(),
                _ => TopologicalCharge::identity(),
            };

            // Create anyon pairs at different positions
            let positions = [
                (qubit_ids.len() as f64 * 10.0, 0.0),
                ((qubit_ids.len() as f64).mul_add(10.0, 5.0), 0.0),
                (qubit_ids.len() as f64 * 10.0, 5.0),
                ((qubit_ids.len() as f64).mul_add(10.0, 5.0), 5.0),
            ];

            let (anyon1_id, anyon2_id) = self
                .core_device
                .create_anyon_pair(charge.clone(), [positions[0], positions[1]])?;

            let (anyon3_id, anyon4_id) = self
                .core_device
                .create_anyon_pair(charge, [positions[2], positions[3]])?;

            // Create topological qubit from four anyons
            let qubit_id = self
                .core_device
                .create_topological_qubit(vec![anyon1_id, anyon2_id, anyon3_id, anyon4_id])?;

            qubit_ids.push(qubit_id);
        }

        Ok(qubit_ids)
    }

    /// Perform a topological X gate via braiding
    pub async fn topological_x_gate(&mut self, qubit_id: usize) -> TopologicalResult<()> {
        let qubit = self.core_device.qubits.get(&qubit_id).ok_or_else(|| {
            TopologicalError::InvalidBraiding(format!("Qubit {qubit_id} not found"))
        })?;

        if qubit.anyons.len() < 4 {
            return Err(TopologicalError::InsufficientAnyons {
                needed: 4,
                available: qubit.anyons.len(),
            });
        }

        // Perform braiding sequence for X gate
        let anyon1_id = qubit.anyons[0];
        let anyon2_id = qubit.anyons[1];

        // Single braid for X rotation
        self.core_device
            .braid_anyons(anyon1_id, anyon2_id, BraidingDirection::Clockwise, 1)?;

        Ok(())
    }

    /// Perform a topological Z gate via braiding
    pub async fn topological_z_gate(&mut self, qubit_id: usize) -> TopologicalResult<()> {
        let qubit = self.core_device.qubits.get(&qubit_id).ok_or_else(|| {
            TopologicalError::InvalidBraiding(format!("Qubit {qubit_id} not found"))
        })?;

        if qubit.anyons.len() < 4 {
            return Err(TopologicalError::InsufficientAnyons {
                needed: 4,
                available: qubit.anyons.len(),
            });
        }

        // Perform braiding sequence for Z gate
        let anyon1_id = qubit.anyons[0];
        let anyon3_id = qubit.anyons[2];

        // Different braiding pattern for Z rotation
        self.core_device.braid_anyons(
            anyon1_id,
            anyon3_id,
            BraidingDirection::Counterclockwise,
            1,
        )?;

        Ok(())
    }

    /// Perform a topological CNOT gate
    pub async fn topological_cnot_gate(
        &mut self,
        control_qubit: usize,
        target_qubit: usize,
    ) -> TopologicalResult<()> {
        // Get anyons from both qubits
        let control_anyons = {
            let qubit = self.core_device.qubits.get(&control_qubit).ok_or_else(|| {
                TopologicalError::InvalidBraiding(format!(
                    "Control qubit {control_qubit} not found"
                ))
            })?;
            qubit.anyons.clone()
        };

        let target_anyons = {
            let qubit = self.core_device.qubits.get(&target_qubit).ok_or_else(|| {
                TopologicalError::InvalidBraiding(format!("Target qubit {target_qubit} not found"))
            })?;
            qubit.anyons.clone()
        };

        // Perform complex braiding sequence for CNOT
        // This is simplified - actual implementation would be more complex
        if !control_anyons.is_empty() && !target_anyons.is_empty() {
            self.core_device.braid_anyons(
                control_anyons[0],
                target_anyons[0],
                BraidingDirection::Clockwise,
                2,
            )?;
        }

        Ok(())
    }

    /// Measure a topological qubit
    pub async fn measure_topological_qubit(&mut self, qubit_id: usize) -> TopologicalResult<bool> {
        let result = self.core_device.measure_qubit(qubit_id)?;

        // Apply measurement fidelity
        let actual_fidelity = thread_rng().gen::<f64>();
        if actual_fidelity < self.config.measurement_fidelity {
            Ok(result)
        } else {
            Ok(!result) // Measurement error
        }
    }

    /// Reset a topological qubit to |0⟩ state
    pub async fn reset_topological_qubit(&mut self, qubit_id: usize) -> TopologicalResult<()> {
        if let Some(qubit) = self.core_device.qubits.get_mut(&qubit_id) {
            qubit.state = super::TopologicalQubitState::zero();
            qubit.braiding_history.clear();
            Ok(())
        } else {
            Err(TopologicalError::InvalidBraiding(format!(
                "Qubit {qubit_id} not found for reset"
            )))
        }
    }

    /// Get device status and diagnostics
    pub async fn get_diagnostics(&self) -> TopologicalDeviceDiagnostics {
        let system_status = self.core_device.get_system_status();

        TopologicalDeviceDiagnostics {
            is_connected: self.is_connected,
            system_status,
            operating_temperature: self.config.operating_temperature,
            topological_gap: self.config.topological_gap,
            average_braiding_fidelity: self.config.braiding_fidelity,
            total_operations: self.braiding_manager.get_operation_history().len(),
            error_rate: 1.0 - self.config.braiding_fidelity,
        }
    }
}

/// Diagnostics information for topological devices
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TopologicalDeviceDiagnostics {
    pub is_connected: bool,
    pub system_status: super::TopologicalSystemStatus,
    pub operating_temperature: f64,
    pub topological_gap: f64,
    pub average_braiding_fidelity: f64,
    pub total_operations: usize,
    pub error_rate: f64,
}

#[async_trait::async_trait]
impl QuantumDevice for EnhancedTopologicalDevice {
    async fn is_available(&self) -> DeviceResult<bool> {
        Ok(self.is_connected && self.config.topological_gap > 0.1)
    }

    async fn qubit_count(&self) -> DeviceResult<usize> {
        Ok(self.core_device.capabilities.max_qubits)
    }

    async fn properties(&self) -> DeviceResult<HashMap<String, String>> {
        let mut props = HashMap::new();
        props.insert("device_type".to_string(), "topological".to_string());
        props.insert(
            "anyon_type".to_string(),
            format!("{:?}", self.core_device.system_type),
        );
        props.insert(
            "max_anyons".to_string(),
            self.core_device.capabilities.max_anyons.to_string(),
        );
        props.insert(
            "max_qubits".to_string(),
            self.core_device.capabilities.max_qubits.to_string(),
        );
        props.insert(
            "braiding_fidelity".to_string(),
            self.config.braiding_fidelity.to_string(),
        );
        props.insert(
            "topological_gap".to_string(),
            self.config.topological_gap.to_string(),
        );
        props.insert(
            "coherence_length".to_string(),
            self.config.coherence_length.to_string(),
        );
        Ok(props)
    }

    async fn is_simulator(&self) -> DeviceResult<bool> {
        Ok(true) // This implementation is a simulator
    }
}

#[async_trait::async_trait]
impl CircuitExecutor for EnhancedTopologicalDevice {
    async fn execute_circuit<const N: usize>(
        &self,
        circuit: &Circuit<N>,
        shots: usize,
    ) -> DeviceResult<CircuitResult> {
        if !self.is_connected {
            return Err(DeviceError::DeviceNotInitialized(
                "Topological device not connected".to_string(),
            ));
        }

        // Simplified circuit execution
        // In practice, this would translate circuit gates to braiding operations
        let mut counts = HashMap::new();

        // Simulate perfect braiding for now
        let all_zeros = "0".repeat(N);
        counts.insert(all_zeros, shots);

        let mut metadata = HashMap::new();
        metadata.insert("device_type".to_string(), "topological".to_string());
        metadata.insert(
            "braiding_fidelity".to_string(),
            self.config.braiding_fidelity.to_string(),
        );
        metadata.insert("execution_time_ms".to_string(), "100".to_string());

        Ok(CircuitResult {
            counts,
            shots,
            metadata,
        })
    }

    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> {
        Ok(N <= self.core_device.capabilities.max_qubits)
    }

    async fn estimated_queue_time<const N: usize>(
        &self,
        _circuit: &Circuit<N>,
    ) -> DeviceResult<Duration> {
        // Topological quantum computers have very long coherence times
        Ok(Duration::from_secs(10))
    }
}

/// Create a Fibonacci anyon topological device
pub fn create_fibonacci_device(
    max_anyons: usize,
    max_qubits: usize,
) -> TopologicalResult<EnhancedTopologicalDevice> {
    let system_type = TopologicalSystemType::NonAbelian {
        anyon_type: NonAbelianAnyonType::Fibonacci,
        fusion_rules: FusionRuleSet::fibonacci(),
    };

    let capabilities = TopologicalCapabilities {
        max_anyons,
        max_qubits,
        supported_anyons: vec![
            TopologicalCharge::identity(),
            TopologicalCharge::fibonacci_tau(),
        ],
        available_operations: vec![
            super::TopologicalOperation::AnyonCreation {
                charge_type: "τ".to_string(),
            },
            super::TopologicalOperation::Braiding {
                direction: BraidingDirection::Clockwise,
            },
            super::TopologicalOperation::Fusion,
            super::TopologicalOperation::Measurement,
        ],
        braiding_fidelity: 0.9999,
        fusion_fidelity: 0.999,
        topological_gap: 1.0,
        coherence_length: 100.0,
    };

    let config = TopologicalDeviceConfig::default();
    let fusion_rules = FusionRuleSet::fibonacci();

    EnhancedTopologicalDevice::new(system_type, fusion_rules, capabilities, config)
}

/// Create an Ising anyon topological device
pub fn create_ising_device(
    max_anyons: usize,
    max_qubits: usize,
) -> TopologicalResult<EnhancedTopologicalDevice> {
    let system_type = TopologicalSystemType::NonAbelian {
        anyon_type: NonAbelianAnyonType::Ising,
        fusion_rules: FusionRuleSet::ising(),
    };

    let capabilities = TopologicalCapabilities {
        max_anyons,
        max_qubits,
        supported_anyons: vec![
            TopologicalCharge::identity(),
            TopologicalCharge::ising_sigma(),
            TopologicalCharge::ising_psi(),
        ],
        available_operations: vec![
            super::TopologicalOperation::AnyonCreation {
                charge_type: "σ".to_string(),
            },
            super::TopologicalOperation::Braiding {
                direction: BraidingDirection::Clockwise,
            },
            super::TopologicalOperation::Fusion,
            super::TopologicalOperation::Measurement,
        ],
        braiding_fidelity: 0.999,
        fusion_fidelity: 0.998,
        topological_gap: 0.5,
        coherence_length: 50.0,
    };

    let config = TopologicalDeviceConfig::default();
    let fusion_rules = FusionRuleSet::ising();

    EnhancedTopologicalDevice::new(system_type, fusion_rules, capabilities, config)
}

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

    #[tokio::test]
    async fn test_fibonacci_device_creation() {
        let device = create_fibonacci_device(100, 10).expect("Failed to create Fibonacci device");
        assert_eq!(device.core_device.capabilities.max_anyons, 100);
        assert_eq!(device.core_device.capabilities.max_qubits, 10);
    }

    #[tokio::test]
    async fn test_device_connection() {
        let mut device = create_fibonacci_device(50, 5).expect("Failed to create Fibonacci device");
        assert!(!device.is_connected);

        device.connect().await.expect("Failed to connect to device");
        assert!(device.is_connected);

        device
            .disconnect()
            .await
            .expect("Failed to disconnect from device");
        assert!(!device.is_connected);
    }

    #[tokio::test]
    async fn test_qubit_initialization() {
        let mut device =
            create_fibonacci_device(100, 10).expect("Failed to create Fibonacci device");
        device.connect().await.expect("Failed to connect to device");

        let qubit_ids = device
            .initialize_topological_qubits(3)
            .await
            .expect("Failed to initialize topological qubits");
        assert_eq!(qubit_ids.len(), 3);
    }

    #[tokio::test]
    async fn test_topological_gates() {
        let mut device =
            create_fibonacci_device(100, 10).expect("Failed to create Fibonacci device");
        device.connect().await.expect("Failed to connect to device");

        let qubit_ids = device
            .initialize_topological_qubits(2)
            .await
            .expect("Failed to initialize topological qubits");

        // Test X gate
        device
            .topological_x_gate(qubit_ids[0])
            .await
            .expect("Failed to apply X gate");

        // Test Z gate
        device
            .topological_z_gate(qubit_ids[0])
            .await
            .expect("Failed to apply Z gate");

        // Test CNOT gate
        device
            .topological_cnot_gate(qubit_ids[0], qubit_ids[1])
            .await
            .expect("Failed to apply CNOT gate");
    }

    #[tokio::test]
    async fn test_measurement() {
        let mut device = create_fibonacci_device(50, 5).expect("Failed to create Fibonacci device");
        device.connect().await.expect("Failed to connect to device");

        let qubit_ids = device
            .initialize_topological_qubits(1)
            .await
            .expect("Failed to initialize topological qubits");
        let result = device
            .measure_topological_qubit(qubit_ids[0])
            .await
            .expect("Failed to measure topological qubit");

        // Result should be boolean
        assert!(result == true || result == false);
    }

    #[tokio::test]
    async fn test_device_diagnostics() {
        let device = create_fibonacci_device(50, 5).expect("Failed to create Fibonacci device");
        let diagnostics = device.get_diagnostics().await;

        assert_eq!(diagnostics.is_connected, false);
        assert!(diagnostics.topological_gap > 0.0);
        assert!(diagnostics.average_braiding_fidelity > 0.0);
    }

    #[tokio::test]
    async fn test_quantum_device_traits() {
        let device = create_ising_device(30, 3).expect("Failed to create Ising device");

        assert!(device
            .is_simulator()
            .await
            .expect("Failed to check if device is simulator"));
        assert_eq!(
            device
                .qubit_count()
                .await
                .expect("Failed to get qubit count"),
            3
        );

        let properties = device
            .properties()
            .await
            .expect("Failed to get device properties");
        assert_eq!(
            properties
                .get("device_type")
                .expect("device_type property not found"),
            "topological"
        );
    }
}