quantrs2_sim/

noise_advanced.rs

#![allow(clippy::needless_range_loop)]

use scirs2_core::Complex64;
use std::f64::consts::PI;
use std::time::Duration;

use quantrs2_core::error::QuantRS2Result;
use quantrs2_core::qubit::QubitId;

use crate::noise::{NoiseChannel, NoiseChannelType, NoiseModel};

/// Two-qubit depolarizing noise channel
#[derive(Debug, Clone)]
pub struct TwoQubitDepolarizingChannel {
    /// First qubit
    pub qubit1: QubitId,

    /// Second qubit
    pub qubit2: QubitId,

    /// Probability of error
    pub probability: f64,
}

impl NoiseChannel for TwoQubitDepolarizingChannel {
    fn name(&self) -> &'static str {
        "TwoQubitDepolarizing"
    }

    fn qubits(&self) -> Vec<QubitId> {
        vec![self.qubit1, self.qubit2]
    }

    fn apply_to_statevector(&self, state: &mut [Complex64]) -> QuantRS2Result<()> {
        let q1_idx = self.qubit1.id() as usize;
        #[allow(clippy::needless_range_loop)]
        let q2_idx = self.qubit2.id() as usize;
        let dim = state.len();

        // Apply two-qubit depolarizing noise with probability p
        if fastrand::f64() < self.probability {
            // Choose randomly between 15 possible Pauli errors (excluding I⊗I)
            let error_type = fastrand::u32(..) % 15;

            // Create a copy of the state to read from
            let state_copy = state.to_vec();

            match error_type {
                0 => {
                    // X⊗I
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx);
                        state[i] = state_copy[flipped_i];
                    }
                }
                1 => {
                    // I⊗X
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q2_idx);
                        state[i] = state_copy[flipped_i];
                    }
                }
                2 => {
                    // X⊗X
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx) ^ (1 << q2_idx);
                        state[i] = state_copy[flipped_i];
                    }
                }
                3 => {
                    // Y⊗I
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx);
                        let phase = if (i >> q1_idx) & 1 == 1 { 1.0 } else { -1.0 };
                        state[i] = state_copy[flipped_i] * Complex64::new(0.0, phase);
                    }
                }
                4 => {
                    // I⊗Y
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q2_idx);
                        let phase = if (i >> q2_idx) & 1 == 1 { 1.0 } else { -1.0 };
                        state[i] = state_copy[flipped_i] * Complex64::new(0.0, phase);
                    }
                }
                5 => {
                    // Y⊗Y
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx) ^ (1 << q2_idx);
                        let phase1 = if (i >> q1_idx) & 1 == 1 { 1.0 } else { -1.0 };
                        let phase2 = if (i >> q2_idx) & 1 == 1 { 1.0 } else { -1.0 };
                        state[i] = state_copy[flipped_i] * Complex64::new(0.0, phase1 * phase2);
                    }
                }
                6 => {
                    // Z⊗I
                    for i in 0..dim {
                        if (i >> q1_idx) & 1 == 1 {
                            state[i] = -state_copy[i];
                        }
                    }
                }
                7 => {
                    // I⊗Z
                    for i in 0..dim {
                        if (i >> q2_idx) & 1 == 1 {
                            state[i] = -state_copy[i];
                        }
                    }
                }
                8 => {
                    // Z⊗Z
                    for i in 0..dim {
                        let parity = ((i >> q1_idx) & 1) ^ ((i >> q2_idx) & 1);
                        if parity == 1 {
                            state[i] = -state_copy[i];
                        }
                    }
                }
                9 => {
                    // X⊗Y
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx) ^ (1 << q2_idx);
                        let phase = if (i >> q2_idx) & 1 == 1 { 1.0 } else { -1.0 };
                        state[i] = state_copy[flipped_i] * Complex64::new(0.0, phase);
                    }
                }
                10 => {
                    // X⊗Z
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx);
                        if (flipped_i >> q2_idx) & 1 == 1 {
                            state[i] = -state_copy[flipped_i];
                        } else {
                            state[i] = state_copy[flipped_i];
                        }
                    }
                }
                11 => {
                    // Y⊗X
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx) ^ (1 << q2_idx);
                        let phase = if (i >> q1_idx) & 1 == 1 { 1.0 } else { -1.0 };
                        state[i] = state_copy[flipped_i] * Complex64::new(0.0, phase);
                    }
                }
                12 => {
                    // Y⊗Z
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q1_idx);
                        let phase = if ((i >> q1_idx) & 1 == 1) ^ ((i >> q2_idx) & 1 == 1) {
                            Complex64::new(0.0, -1.0)
                        } else {
                            Complex64::new(0.0, 1.0)
                        };
                        state[i] = state_copy[flipped_i] * phase;
                    }
                }
                13 => {
                    // Z⊗X
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q2_idx);
                        if (i >> q1_idx) & 1 == 1 {
                            state[i] = -state_copy[flipped_i];
                        } else {
                            state[i] = state_copy[flipped_i];
                        }
                    }
                }
                14 => {
                    // Z⊗Y
                    for i in 0..dim {
                        let flipped_i = i ^ (1 << q2_idx);
                        let phase = if ((i >> q1_idx) & 1 == 1) ^ ((i >> q2_idx) & 1 == 1) {
                            Complex64::new(0.0, -1.0)
                        } else {
                            Complex64::new(0.0, 1.0)
                        };
                        state[i] = state_copy[flipped_i] * phase;
                    }
                }
                _ => unreachable!(),
            }
        }

        Ok(())
    }

    fn kraus_operators(&self) -> Vec<Vec<Complex64>> {
        // Two-qubit depolarizing has 16 Kraus operators (15 Pauli errors + identity)
        // This is a simplified implementation since full representation is large
        let p = self.probability;
        let sqrt_1_minus_p = (1.0 - p).sqrt();
        let sqrt_p_15 = (p / 15.0).sqrt();

        // Return placeholder Kraus operators
        // In a full implementation, this would be a 16×16 matrix
        vec![
            vec![Complex64::new(sqrt_1_minus_p, 0.0)],
            vec![Complex64::new(sqrt_p_15, 0.0)],
        ]
    }

    fn probability(&self) -> f64 {
        self.probability
    }
}

/// Thermal relaxation noise channel (combination of T1 and T2 effects)
#[derive(Debug, Clone)]
pub struct ThermalRelaxationChannel {
    /// Target qubit
    pub target: QubitId,

    /// T1 relaxation time (seconds)
    pub t1: f64,

    /// T2 pure dephasing time (seconds)
    pub t2: f64,

    /// Gate time (seconds)
    pub gate_time: f64,

    /// Excited state population at thermal equilibrium (0.0 to 1.0)
    pub excited_state_population: f64,
}

impl NoiseChannel for ThermalRelaxationChannel {
    fn name(&self) -> &'static str {
        "ThermalRelaxation"
    }

    fn qubits(&self) -> Vec<QubitId> {
        vec![self.target]
    }

    fn apply_to_statevector(&self, state: &mut [Complex64]) -> QuantRS2Result<()> {
        let target_idx = self.target.id() as usize;
        let dim = state.len();

        // Calculate relaxation and dephasing probabilities
        let p_reset = 1.0 - (-self.gate_time / self.t1).exp();
        let p_phase = 0.5 * (1.0 - (-self.gate_time / self.t2).exp());

        // Create a copy of the state for reading
        let state_copy = state.to_vec();

        // Apply thermal relaxation
        // First apply amplitude damping (relaxation)
        for i in 0..dim {
            if (i >> target_idx) & 1 == 1 {
                // This basis state has the target qubit in |1⟩
                let base_idx = i & !(1 << target_idx); // Flip the target bit to 0

                // Apply relaxation with probability p_reset
                if fastrand::f64() < p_reset {
                    // With probability (1-p_eq), collapse to |0⟩ state
                    // With probability p_eq, collapse to |1⟩ state (thermal equilibrium)
                    if fastrand::f64() < self.excited_state_population {
                        // Stay in |1⟩ due to thermal excitation
                        state[i] = state_copy[i];
                    } else {
                        // Collapse to |0⟩
                        state[base_idx] += state_copy[i];
                        state[i] = Complex64::new(0.0, 0.0);
                    }
                } else {
                    // No relaxation occurs, but apply sqrt(1-p) factor
                    state[i] = state_copy[i] * Complex64::new((1.0 - p_reset).sqrt(), 0.0);
                }
            }
        }

        // Then apply phase damping (dephasing on top of amplitude damping)
        for i in 0..dim {
            if (i >> target_idx) & 1 == 1 {
                // Apply additional pure dephasing
                if fastrand::f64() < p_phase {
                    // Random phase
                    state[i] *= Complex64::new(-1.0, 0.0); // Apply phase flip
                }
            }
        }

        // Normalize the state
        NoiseChannelType::normalize_state(state);

        Ok(())
    }

    fn kraus_operators(&self) -> Vec<Vec<Complex64>> {
        // For thermal relaxation, we would typically have 3 Kraus operators
        // This is a simplified implementation
        let p_reset = 1.0 - (-self.gate_time / self.t1).exp();
        let p_phase = 0.5 * (1.0 - (-self.gate_time / self.t2).exp());

        // Return placeholder Kraus operators
        vec![vec![Complex64::new(1.0 - p_reset - p_phase, 0.0)]]
    }

    fn probability(&self) -> f64 {
        // Return the combined probability of an error occurring
        let p_reset = 1.0 - (-self.gate_time / self.t1).exp();
        let p_phase = 0.5 * (1.0 - (-self.gate_time / self.t2).exp());
        p_reset + p_phase - p_reset * p_phase // Combined probability
    }
}

/// Crosstalk noise channel for adjacent qubits
#[derive(Debug, Clone)]
pub struct CrosstalkChannel {
    /// Primary qubit
    pub primary: QubitId,

    /// Neighbor qubit
    pub neighbor: QubitId,

    /// Crosstalk strength (0.0 to 1.0)
    pub strength: f64,
}

impl NoiseChannel for CrosstalkChannel {
    fn name(&self) -> &'static str {
        "Crosstalk"
    }

    fn qubits(&self) -> Vec<QubitId> {
        vec![self.primary, self.neighbor]
    }

    fn apply_to_statevector(&self, state: &mut [Complex64]) -> QuantRS2Result<()> {
        let primary_idx = self.primary.id() as usize;
        let neighbor_idx = self.neighbor.id() as usize;
        let dim = state.len();

        // Apply crosstalk with probability based on strength
        if fastrand::f64() < self.strength {
            // Create a copy of the state for reading
            let state_copy = state.to_vec();

            // Randomly select an effect (simplified model):
            // 1. ZZ interaction
            // 2. Neighbor rotation
            let effect = fastrand::u32(..) % 2;

            match effect {
                0 => {
                    // ZZ interaction
                    for i in 0..dim {
                        let parity = ((i >> primary_idx) & 1) ^ ((i >> neighbor_idx) & 1);
                        if parity == 1 {
                            // Apply phase shift if qubits have different parity
                            let phase = fastrand::f64() * PI;
                            state[i] *= Complex64::new(phase.cos(), phase.sin());
                        }
                    }
                }
                1 => {
                    // Small rotation on neighbor when primary qubit is |1⟩
                    for i in 0..dim {
                        if (i >> primary_idx) & 1 == 1 {
                            // Primary qubit is |1⟩, apply partial X rotation to neighbor
                            let neighbor_bit = (i >> neighbor_idx) & 1;
                            let flipped_i = i ^ (1 << neighbor_idx);

                            // Small, random amplitude swap
                            let theta: f64 = fastrand::f64() * 0.2; // Small angle
                            let cos_theta = theta.cos();
                            let sin_theta = theta.sin();

                            let amp_original = state_copy[i];
                            let amp_flipped = state_copy[flipped_i];

                            if neighbor_bit == 0 {
                                state[i] = amp_original * Complex64::new(cos_theta, 0.0)
                                    + amp_flipped * Complex64::new(sin_theta, 0.0);
                                state[flipped_i] = amp_original * Complex64::new(-sin_theta, 0.0)
                                    + amp_flipped * Complex64::new(cos_theta, 0.0);
                            } else {
                                state[i] = amp_original * Complex64::new(cos_theta, 0.0)
                                    - amp_flipped * Complex64::new(sin_theta, 0.0);
                                state[flipped_i] = amp_original * Complex64::new(sin_theta, 0.0)
                                    + amp_flipped * Complex64::new(cos_theta, 0.0);
                            }
                        }
                    }
                }
                _ => unreachable!(),
            }
        }

        // Normalize the state
        NoiseChannelType::normalize_state(state);

        Ok(())
    }

    fn kraus_operators(&self) -> Vec<Vec<Complex64>> {
        // Crosstalk noise is complex and typically needs multiple Kraus operators
        // This is a placeholder for a full implementation
        vec![vec![Complex64::new(1.0, 0.0)]]
    }

    fn probability(&self) -> f64 {
        self.strength
    }
}

/// Extension to NoiseChannelType to include advanced noise channels
#[derive(Debug, Clone)]
pub enum AdvancedNoiseChannelType {
    /// Base noise channel types
    Base(NoiseChannelType),

    /// Two-qubit depolarizing channel
    TwoQubitDepolarizing(TwoQubitDepolarizingChannel),

    /// Thermal relaxation channel
    ThermalRelaxation(ThermalRelaxationChannel),

    /// Crosstalk channel
    Crosstalk(CrosstalkChannel),
}

impl AdvancedNoiseChannelType {
    /// Get the name of the noise channel
    pub fn name(&self) -> &'static str {
        match self {
            Self::Base(ch) => ch.name(),
            Self::TwoQubitDepolarizing(ch) => ch.name(),
            Self::ThermalRelaxation(ch) => ch.name(),
            Self::Crosstalk(ch) => ch.name(),
        }
    }

    /// Get the qubits this channel affects
    pub fn qubits(&self) -> Vec<QubitId> {
        match self {
            Self::Base(ch) => ch.qubits(),
            Self::TwoQubitDepolarizing(ch) => ch.qubits(),
            Self::ThermalRelaxation(ch) => ch.qubits(),
            Self::Crosstalk(ch) => ch.qubits(),
        }
    }

    /// Apply the noise channel to a state vector
    pub fn apply_to_statevector(&self, state: &mut [Complex64]) -> QuantRS2Result<()> {
        match self {
            Self::Base(ch) => ch.apply_to_statevector(state),
            Self::TwoQubitDepolarizing(ch) => ch.apply_to_statevector(state),
            Self::ThermalRelaxation(ch) => ch.apply_to_statevector(state),
            Self::Crosstalk(ch) => ch.apply_to_statevector(state),
        }
    }

    /// Get the probability of the noise occurring
    pub fn probability(&self) -> f64 {
        match self {
            Self::Base(ch) => ch.probability(),
            Self::TwoQubitDepolarizing(ch) => ch.probability(),
            Self::ThermalRelaxation(ch) => ch.probability(),
            Self::Crosstalk(ch) => ch.probability(),
        }
    }
}

/// Advanced noise model that supports the new noise channel types
#[derive(Debug, Clone)]
pub struct AdvancedNoiseModel {
    /// List of noise channels
    pub channels: Vec<AdvancedNoiseChannelType>,

    /// Whether the noise is applied after each gate
    pub per_gate: bool,
}

impl AdvancedNoiseModel {
    /// Create a new empty noise model
    pub fn new(per_gate: bool) -> Self {
        Self {
            channels: Vec::new(),
            per_gate,
        }
    }

    /// Add a basic noise channel to the model
    pub fn add_base_channel(&mut self, channel: NoiseChannelType) -> &mut Self {
        self.channels.push(AdvancedNoiseChannelType::Base(channel));
        self
    }

    /// Add a two-qubit depolarizing noise channel to the model
    pub fn add_two_qubit_depolarizing(
        &mut self,
        channel: TwoQubitDepolarizingChannel,
    ) -> &mut Self {
        self.channels
            .push(AdvancedNoiseChannelType::TwoQubitDepolarizing(channel));
        self
    }

    /// Add a thermal relaxation noise channel to the model
    pub fn add_thermal_relaxation(&mut self, channel: ThermalRelaxationChannel) -> &mut Self {
        self.channels
            .push(AdvancedNoiseChannelType::ThermalRelaxation(channel));
        self
    }

    /// Add a crosstalk noise channel to the model
    pub fn add_crosstalk(&mut self, channel: CrosstalkChannel) -> &mut Self {
        self.channels
            .push(AdvancedNoiseChannelType::Crosstalk(channel));
        self
    }

    /// Apply all noise channels to a state vector
    pub fn apply_to_statevector(&self, state: &mut [Complex64]) -> QuantRS2Result<()> {
        for channel in &self.channels {
            channel.apply_to_statevector(state)?;
        }

        // Normalize the state vector after applying all noise channels
        NoiseChannelType::normalize_state(state);

        Ok(())
    }

    /// Get the total number of channels
    pub fn num_channels(&self) -> usize {
        self.channels.len()
    }

    /// Convert to basic noise model (for backward compatibility)
    pub fn to_basic_model(&self) -> NoiseModel {
        let mut model = NoiseModel::new(self.per_gate);

        for channel in &self.channels {
            if let AdvancedNoiseChannelType::Base(ch) = channel {
                model.channels.push(ch.clone());
            }
        }

        model
    }
}

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

/// Builder for realistic device noise models
pub struct RealisticNoiseModelBuilder {
    model: AdvancedNoiseModel,
}

impl RealisticNoiseModelBuilder {
    /// Create a new noise model builder
    pub fn new(per_gate: bool) -> Self {
        Self {
            model: AdvancedNoiseModel::new(per_gate),
        }
    }

    /// Add realistic IBM Quantum device noise parameters
    pub fn with_ibm_device_noise(mut self, qubits: &[QubitId], device_name: &str) -> Self {
        match device_name {
            "ibmq_lima" | "ibmq_belem" | "ibmq_quito" => {
                // 5-qubit IBM Quantum Falcon processors
                // Parameters are approximate and based on typical values

                // Relaxation and dephasing times
                let t1_values = [115e-6, 100e-6, 120e-6, 105e-6, 110e-6]; // ~100 microseconds
                let t2_values = [95e-6, 80e-6, 100e-6, 90e-6, 85e-6]; // ~90 microseconds

                // Single-qubit gates
                let gate_time_1q = 35e-9; // 35 nanoseconds
                let gate_error_1q = 0.001; // 0.1% error rate

                // Two-qubit gates (CNOT)
                let _gate_time_2q = 300e-9; // 300 nanoseconds
                let gate_error_2q = 0.01; // 1% error rate

                // Readout errors
                let readout_error = 0.025; // 2.5% error

                // Add individual qubit noise
                for (i, &qubit) in qubits.iter().enumerate().take(5) {
                    let t1 = t1_values[i % 5];
                    let t2 = t2_values[i % 5];

                    // Add thermal relaxation
                    self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                        target: qubit,
                        t1,
                        t2,
                        gate_time: gate_time_1q,
                        excited_state_population: 0.01, // ~1% thermal excitation
                    });

                    // Add depolarizing noise for single-qubit gates
                    self.model.add_base_channel(NoiseChannelType::Depolarizing(
                        crate::noise::DepolarizingChannel {
                            target: qubit,
                            probability: gate_error_1q,
                        },
                    ));

                    // Add readout error as a bit flip channel
                    self.model.add_base_channel(NoiseChannelType::BitFlip(
                        crate::noise::BitFlipChannel {
                            target: qubit,
                            probability: readout_error,
                        },
                    ));
                }

                // Add two-qubit gate noise (for nearest-neighbor connectivity)
                for i in 0..qubits.len().saturating_sub(1) {
                    let q1 = qubits[i];
                    let q2 = qubits[i + 1];

                    // Add two-qubit depolarizing noise
                    self.model
                        .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                            qubit1: q1,
                            qubit2: q2,
                            probability: gate_error_2q,
                        });

                    // Add crosstalk between adjacent qubits
                    self.model.add_crosstalk(CrosstalkChannel {
                        primary: q1,
                        neighbor: q2,
                        strength: 0.003, // 0.3% crosstalk
                    });
                }
            }
            "ibmq_bogota" | "ibmq_santiago" | "ibmq_casablanca" => {
                // 5-qubit IBM Quantum Falcon processors (newer)
                // Parameters are approximate and based on typical values

                // Relaxation and dephasing times
                let t1_values = [140e-6, 130e-6, 145e-6, 135e-6, 150e-6]; // ~140 microseconds
                let t2_values = [120e-6, 110e-6, 125e-6, 115e-6, 130e-6]; // ~120 microseconds

                // Single-qubit gates
                let gate_time_1q = 30e-9; // 30 nanoseconds
                let gate_error_1q = 0.0005; // 0.05% error rate

                // Two-qubit gates (CNOT)
                let _gate_time_2q = 250e-9; // 250 nanoseconds
                let gate_error_2q = 0.008; // 0.8% error rate

                // Readout errors
                let readout_error = 0.02; // 2% error

                // Add individual qubit noise
                for (i, &qubit) in qubits.iter().enumerate().take(5) {
                    let t1 = t1_values[i % 5];
                    let t2 = t2_values[i % 5];

                    // Add thermal relaxation
                    self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                        target: qubit,
                        t1,
                        t2,
                        gate_time: gate_time_1q,
                        excited_state_population: 0.008, // ~0.8% thermal excitation
                    });

                    // Add depolarizing noise for single-qubit gates
                    self.model.add_base_channel(NoiseChannelType::Depolarizing(
                        crate::noise::DepolarizingChannel {
                            target: qubit,
                            probability: gate_error_1q,
                        },
                    ));

                    // Add readout error as a bit flip channel
                    self.model.add_base_channel(NoiseChannelType::BitFlip(
                        crate::noise::BitFlipChannel {
                            target: qubit,
                            probability: readout_error,
                        },
                    ));
                }

                // Add two-qubit gate noise (for nearest-neighbor connectivity)
                for i in 0..qubits.len().saturating_sub(1) {
                    let q1 = qubits[i];
                    let q2 = qubits[i + 1];

                    // Add two-qubit depolarizing noise
                    self.model
                        .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                            qubit1: q1,
                            qubit2: q2,
                            probability: gate_error_2q,
                        });

                    // Add crosstalk between adjacent qubits
                    self.model.add_crosstalk(CrosstalkChannel {
                        primary: q1,
                        neighbor: q2,
                        strength: 0.002, // 0.2% crosstalk
                    });
                }
            }
            "ibm_cairo" | "ibm_hanoi" | "ibm_auckland" => {
                // 27-qubit IBM Quantum Falcon processors
                // Parameters are approximate and based on typical values

                // Relaxation and dephasing times (average values)
                let t1 = 130e-6; // 130 microseconds
                let t2 = 100e-6; // 100 microseconds

                // Single-qubit gates
                let gate_time_1q = 35e-9; // 35 nanoseconds
                let gate_error_1q = 0.0004; // 0.04% error rate

                // Two-qubit gates (CNOT)
                let _gate_time_2q = 275e-9; // 275 nanoseconds
                let gate_error_2q = 0.007; // 0.7% error rate

                // Readout errors
                let readout_error = 0.018; // 1.8% error

                // Add individual qubit noise
                for &qubit in qubits {
                    // Add thermal relaxation
                    self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                        target: qubit,
                        t1,
                        t2,
                        gate_time: gate_time_1q,
                        excited_state_population: 0.007, // ~0.7% thermal excitation
                    });

                    // Add depolarizing noise for single-qubit gates
                    self.model.add_base_channel(NoiseChannelType::Depolarizing(
                        crate::noise::DepolarizingChannel {
                            target: qubit,
                            probability: gate_error_1q,
                        },
                    ));

                    // Add readout error as a bit flip channel
                    self.model.add_base_channel(NoiseChannelType::BitFlip(
                        crate::noise::BitFlipChannel {
                            target: qubit,
                            probability: readout_error,
                        },
                    ));
                }

                // Add two-qubit gate noise (for nearest-neighbor connectivity)
                for i in 0..qubits.len().saturating_sub(1) {
                    let q1 = qubits[i];
                    let q2 = qubits[i + 1];

                    // Add two-qubit depolarizing noise
                    self.model
                        .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                            qubit1: q1,
                            qubit2: q2,
                            probability: gate_error_2q,
                        });

                    // Add crosstalk between adjacent qubits
                    self.model.add_crosstalk(CrosstalkChannel {
                        primary: q1,
                        neighbor: q2,
                        strength: 0.0015, // 0.15% crosstalk
                    });
                }
            }
            "ibm_washington" | "ibm_eagle" => {
                // 127-qubit IBM Quantum Eagle processors
                // Parameters are approximate and based on typical values

                // Relaxation and dephasing times (average values)
                let t1 = 150e-6; // 150 microseconds
                let t2 = 120e-6; // 120 microseconds

                // Single-qubit gates
                let gate_time_1q = 30e-9; // 30 nanoseconds
                let gate_error_1q = 0.0003; // 0.03% error rate

                // Two-qubit gates (CNOT)
                let _gate_time_2q = 220e-9; // 220 nanoseconds
                let gate_error_2q = 0.006; // 0.6% error rate

                // Readout errors
                let readout_error = 0.015; // 1.5% error

                // Add individual qubit noise
                for &qubit in qubits {
                    // Add thermal relaxation
                    self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                        target: qubit,
                        t1,
                        t2,
                        gate_time: gate_time_1q,
                        excited_state_population: 0.006, // ~0.6% thermal excitation
                    });

                    // Add depolarizing noise for single-qubit gates
                    self.model.add_base_channel(NoiseChannelType::Depolarizing(
                        crate::noise::DepolarizingChannel {
                            target: qubit,
                            probability: gate_error_1q,
                        },
                    ));

                    // Add readout error as a bit flip channel
                    self.model.add_base_channel(NoiseChannelType::BitFlip(
                        crate::noise::BitFlipChannel {
                            target: qubit,
                            probability: readout_error,
                        },
                    ));
                }

                // Add two-qubit gate noise (for nearest-neighbor connectivity)
                for i in 0..qubits.len().saturating_sub(1) {
                    let q1 = qubits[i];
                    let q2 = qubits[i + 1];

                    // Add two-qubit depolarizing noise
                    self.model
                        .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                            qubit1: q1,
                            qubit2: q2,
                            probability: gate_error_2q,
                        });

                    // Add crosstalk between adjacent qubits
                    self.model.add_crosstalk(CrosstalkChannel {
                        primary: q1,
                        neighbor: q2,
                        strength: 0.001, // 0.1% crosstalk
                    });
                }
            }
            _ => {
                // Generic IBM Quantum device (conservative estimates)
                // Parameters are approximate and based on typical values

                // Relaxation and dephasing times (average values)
                let t1 = 100e-6; // 100 microseconds
                let t2 = 80e-6; // 80 microseconds

                // Single-qubit gates
                let gate_time_1q = 40e-9; // 40 nanoseconds
                let gate_error_1q = 0.001; // 0.1% error rate

                // Two-qubit gates (CNOT)
                let _gate_time_2q = 300e-9; // 300 nanoseconds
                let gate_error_2q = 0.01; // 1% error rate

                // Readout errors
                let readout_error = 0.025; // 2.5% error

                // Add individual qubit noise
                for &qubit in qubits {
                    // Add thermal relaxation
                    self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                        target: qubit,
                        t1,
                        t2,
                        gate_time: gate_time_1q,
                        excited_state_population: 0.01, // ~1% thermal excitation
                    });

                    // Add depolarizing noise for single-qubit gates
                    self.model.add_base_channel(NoiseChannelType::Depolarizing(
                        crate::noise::DepolarizingChannel {
                            target: qubit,
                            probability: gate_error_1q,
                        },
                    ));

                    // Add readout error as a bit flip channel
                    self.model.add_base_channel(NoiseChannelType::BitFlip(
                        crate::noise::BitFlipChannel {
                            target: qubit,
                            probability: readout_error,
                        },
                    ));
                }

                // Add two-qubit gate noise (for nearest-neighbor connectivity)
                for i in 0..qubits.len().saturating_sub(1) {
                    let q1 = qubits[i];
                    let q2 = qubits[i + 1];

                    // Add two-qubit depolarizing noise
                    self.model
                        .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                            qubit1: q1,
                            qubit2: q2,
                            probability: gate_error_2q,
                        });

                    // Add crosstalk between adjacent qubits
                    self.model.add_crosstalk(CrosstalkChannel {
                        primary: q1,
                        neighbor: q2,
                        strength: 0.003, // 0.3% crosstalk
                    });
                }
            }
        }

        self
    }

    /// Add realistic Rigetti device noise parameters
    pub fn with_rigetti_device_noise(mut self, qubits: &[QubitId], device_name: &str) -> Self {
        match device_name {
            "Aspen-M-3" | "Aspen-M-2" => {
                // Rigetti Aspen-M series processors
                // Parameters are approximate and based on typical values

                // Relaxation and dephasing times (average values)
                let t1 = 20e-6; // 20 microseconds
                let t2 = 15e-6; // 15 microseconds

                // Single-qubit gates
                let gate_time_1q = 50e-9; // 50 nanoseconds
                let gate_error_1q = 0.0015; // 0.15% error rate

                // Two-qubit gates (CZ)
                let _gate_time_2q = 220e-9; // 220 nanoseconds
                let gate_error_2q = 0.02; // 2% error rate

                // Readout errors
                let readout_error = 0.03; // 3% error

                // Add individual qubit noise
                for &qubit in qubits {
                    // Add thermal relaxation
                    self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                        target: qubit,
                        t1,
                        t2,
                        gate_time: gate_time_1q,
                        excited_state_population: 0.02, // ~2% thermal excitation
                    });

                    // Add depolarizing noise for single-qubit gates
                    self.model.add_base_channel(NoiseChannelType::Depolarizing(
                        crate::noise::DepolarizingChannel {
                            target: qubit,
                            probability: gate_error_1q,
                        },
                    ));

                    // Add readout error as a bit flip channel
                    self.model.add_base_channel(NoiseChannelType::BitFlip(
                        crate::noise::BitFlipChannel {
                            target: qubit,
                            probability: readout_error,
                        },
                    ));
                }

                // Add two-qubit gate noise (for nearest-neighbor connectivity)
                for i in 0..qubits.len().saturating_sub(1) {
                    let q1 = qubits[i];
                    let q2 = qubits[i + 1];

                    // Add two-qubit depolarizing noise
                    self.model
                        .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                            qubit1: q1,
                            qubit2: q2,
                            probability: gate_error_2q,
                        });

                    // Add crosstalk between adjacent qubits
                    self.model.add_crosstalk(CrosstalkChannel {
                        primary: q1,
                        neighbor: q2,
                        strength: 0.004, // 0.4% crosstalk
                    });
                }
            }
            _ => {
                // Generic Rigetti device (conservative estimates)
                // Parameters are approximate and based on typical values

                // Relaxation and dephasing times (average values)
                let t1 = 15e-6; // 15 microseconds
                let t2 = 12e-6; // 12 microseconds

                // Single-qubit gates
                let gate_time_1q = 60e-9; // 60 nanoseconds
                let gate_error_1q = 0.002; // 0.2% error rate

                // Two-qubit gates (CZ)
                let _gate_time_2q = 250e-9; // 250 nanoseconds
                let gate_error_2q = 0.025; // 2.5% error rate

                // Readout errors
                let readout_error = 0.035; // 3.5% error

                // Add individual qubit noise
                for &qubit in qubits {
                    // Add thermal relaxation
                    self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                        target: qubit,
                        t1,
                        t2,
                        gate_time: gate_time_1q,
                        excited_state_population: 0.025, // ~2.5% thermal excitation
                    });

                    // Add depolarizing noise for single-qubit gates
                    self.model.add_base_channel(NoiseChannelType::Depolarizing(
                        crate::noise::DepolarizingChannel {
                            target: qubit,
                            probability: gate_error_1q,
                        },
                    ));

                    // Add readout error as a bit flip channel
                    self.model.add_base_channel(NoiseChannelType::BitFlip(
                        crate::noise::BitFlipChannel {
                            target: qubit,
                            probability: readout_error,
                        },
                    ));
                }

                // Add two-qubit gate noise (for nearest-neighbor connectivity)
                for i in 0..qubits.len().saturating_sub(1) {
                    let q1 = qubits[i];
                    let q2 = qubits[i + 1];

                    // Add two-qubit depolarizing noise
                    self.model
                        .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                            qubit1: q1,
                            qubit2: q2,
                            probability: gate_error_2q,
                        });

                    // Add crosstalk between adjacent qubits
                    self.model.add_crosstalk(CrosstalkChannel {
                        primary: q1,
                        neighbor: q2,
                        strength: 0.005, // 0.5% crosstalk
                    });
                }
            }
        }

        self
    }

    /// Add custom thermal relaxation parameters
    pub fn with_custom_thermal_relaxation(
        mut self,
        qubits: &[QubitId],
        t1: Duration,
        t2: Duration,
        gate_time: Duration,
    ) -> Self {
        let t1_seconds = t1.as_secs_f64();
        let t2_seconds = t2.as_secs_f64();
        let gate_time_seconds = gate_time.as_secs_f64();

        for &qubit in qubits {
            self.model.add_thermal_relaxation(ThermalRelaxationChannel {
                target: qubit,
                t1: t1_seconds,
                t2: t2_seconds,
                gate_time: gate_time_seconds,
                excited_state_population: 0.01, // Default 1% thermal excitation
            });
        }

        self
    }

    /// Add custom two-qubit depolarizing noise
    pub fn with_custom_two_qubit_noise(
        mut self,
        qubit_pairs: &[(QubitId, QubitId)],
        probability: f64,
    ) -> Self {
        for &(q1, q2) in qubit_pairs {
            self.model
                .add_two_qubit_depolarizing(TwoQubitDepolarizingChannel {
                    qubit1: q1,
                    qubit2: q2,
                    probability,
                });
        }

        self
    }

    /// Add custom crosstalk noise between pairs of qubits
    pub fn with_custom_crosstalk(
        mut self,
        qubit_pairs: &[(QubitId, QubitId)],
        strength: f64,
    ) -> Self {
        for &(q1, q2) in qubit_pairs {
            self.model.add_crosstalk(CrosstalkChannel {
                primary: q1,
                neighbor: q2,
                strength,
            });
        }

        self
    }

    /// Build the noise model
    pub fn build(self) -> AdvancedNoiseModel {
        self.model
    }
}