"""
Quantum Machine Learning Module
This module provides quantum machine learning functionality including
quantum neural networks, variational classifiers, and quantum ML algorithms.
"""
import logging
from typing import Dict, Any, List, Optional, Union, Tuple
import asyncio
import numpy as np
logger = logging.getLogger(__name__)
async def quantum_neural_network(
input_data: List[List[float]],
labels: List[int],
n_qubits: int = 4,
n_layers: int = 2,
learning_rate: float = 0.1,
epochs: int = 50
) -> Dict[str, Any]:
"""
Train a quantum neural network.
Args:
input_data: Training input data
labels: Training labels
n_qubits: Number of qubits
n_layers: Number of variational layers
learning_rate: Learning rate
epochs: Number of training epochs
Returns:
QNN training results
"""
logger.info(f"Training QNN with {n_qubits} qubits and {n_layers} layers")
try:
import pennylane as qml
from pennylane import numpy as pnp
# Validate input data
if not input_data or not labels:
raise ValueError("Input data and labels cannot be empty")
input_data = np.array(input_data)
labels = np.array(labels)
# Ensure data dimensionality matches n_qubits
if input_data.shape[1] > n_qubits:
logger.warning(f"Input dimension {input_data.shape[1]} > n_qubits {n_qubits}, truncating data")
input_data = input_data[:, :n_qubits]
elif input_data.shape[1] < n_qubits:
# Pad with zeros
padding = np.zeros((input_data.shape[0], n_qubits - input_data.shape[1]))
input_data = np.concatenate([input_data, padding], axis=1)
# Create device
dev = qml.device('default.qubit', wires=n_qubits)
# Define QNN architecture
def data_encoding(x):
"""Encode classical data into quantum states."""
for i in range(n_qubits):
qml.RY(x[i], wires=i)
def variational_layer(params):
"""Variational layer with parameterized gates."""
# Rotation gates
for i in range(n_qubits):
qml.RY(params[i], wires=i)
# Entangling gates
for i in range(n_qubits - 1):
qml.CNOT(wires=[i, i + 1])
@qml.qnode(dev)
def qnn_circuit(inputs, params):
"""Quantum neural network circuit."""
# Data encoding
data_encoding(inputs)
# Variational layers
for layer in range(n_layers):
layer_params = params[layer * n_qubits:(layer + 1) * n_qubits]
variational_layer(layer_params)
# Measurement
return qml.expval(qml.PauliZ(0))
# Initialize parameters
n_params = n_layers * n_qubits
params = pnp.random.uniform(0, 2 * pnp.pi, n_params, requires_grad=True)
# Define cost function
def cost_function(params, X, y):
predictions = []
for x in X:
pred = qnn_circuit(x, params)
predictions.append(pred)
predictions = pnp.array(predictions)
# Binary cross-entropy loss (adapted for quantum outputs)
# Convert Pauli-Z expectation values (-1 to 1) to probabilities (0 to 1)
probs = (predictions + 1) / 2
# Avoid log(0) issues
probs = pnp.clip(probs, 1e-7, 1 - 1e-7)
loss = -pnp.mean(y * pnp.log(probs) + (1 - y) * pnp.log(1 - probs))
return loss
# Training loop
optimizer = qml.AdamOptimizer(stepsize=learning_rate)
cost_history = []
accuracy_history = []
for epoch in range(epochs):
# Update parameters
params, cost = optimizer.step_and_cost(
lambda p: cost_function(p, input_data, labels), params
)
cost_history.append(float(cost))
# Calculate accuracy
predictions = []
for x in input_data:
pred_val = qnn_circuit(x, params)
# Convert to binary prediction
pred_class = 1 if pred_val > 0 else 0
predictions.append(pred_class)
accuracy = np.mean(np.array(predictions) == labels)
accuracy_history.append(float(accuracy))
if epoch % 10 == 0:
logger.info(f"Epoch {epoch}: Cost = {cost:.4f}, Accuracy = {accuracy:.4f}")
# Final predictions
final_predictions = []
prediction_probabilities = []
for x in input_data:
pred_val = qnn_circuit(x, params)
pred_class = 1 if pred_val > 0 else 0
pred_prob = (pred_val + 1) / 2 # Convert to probability
final_predictions.append(pred_class)
prediction_probabilities.append(float(pred_prob))
final_accuracy = np.mean(np.array(final_predictions) == labels)
return {
'success': True,
'n_qubits': n_qubits,
'n_layers': n_layers,
'epochs': epochs,
'final_accuracy': float(final_accuracy),
'final_cost': float(cost_history[-1]),
'cost_history': cost_history,
'accuracy_history': accuracy_history,
'optimal_parameters': params.tolist(),
'predictions': final_predictions,
'prediction_probabilities': prediction_probabilities,
'training_samples': len(input_data)
}
except Exception as e:
logger.error(f"Error in QNN training: {e}")
return {'success': False, 'error': str(e)}
async def variational_classifier(
training_data: List[List[float]],
training_labels: List[int],
test_data: List[List[float]],
ansatz_type: str = "basic",
optimizer: str = "adam",
max_iterations: int = 100
) -> Dict[str, Any]:
"""
Train a variational quantum classifier.
Args:
training_data: Training feature vectors
training_labels: Training labels
test_data: Test feature vectors
ansatz_type: Type of ansatz circuit
optimizer: Classical optimizer
max_iterations: Maximum training iterations
Returns:
Classification results
"""
logger.info(f"Training variational classifier with {ansatz_type} ansatz")
try:
import pennylane as qml
from pennylane import numpy as pnp
# Convert to numpy arrays
X_train = np.array(training_data)
y_train = np.array(training_labels)
X_test = np.array(test_data)
# Determine number of qubits based on feature dimension
n_features = X_train.shape[1]
n_qubits = max(2, min(n_features, 6)) # Limit qubits for simulation
# Truncate or pad features if necessary
if n_features > n_qubits:
X_train = X_train[:, :n_qubits]
X_test = X_test[:, :n_qubits]
elif n_features < n_qubits:
pad_train = np.zeros((X_train.shape[0], n_qubits - n_features))
pad_test = np.zeros((X_test.shape[0], n_qubits - n_features))
X_train = np.concatenate([X_train, pad_train], axis=1)
X_test = np.concatenate([X_test, pad_test], axis=1)
# Normalize features
X_train = X_train / (np.linalg.norm(X_train, axis=1, keepdims=True) + 1e-8)
X_test = X_test / (np.linalg.norm(X_test, axis=1, keepdims=True) + 1e-8)
# Create device
dev = qml.device('default.qubit', wires=n_qubits)
# Define ansatz circuits
def basic_ansatz(x, params):
# Data encoding
for i in range(n_qubits):
qml.RY(x[i] * np.pi, wires=i)
# Variational circuit
for i in range(n_qubits):
qml.RY(params[i], wires=i)
for i in range(n_qubits - 1):
qml.CNOT(wires=[i, i + 1])
def hardware_efficient_ansatz(x, params):
# Data encoding
for i in range(n_qubits):
qml.RY(x[i] * np.pi, wires=i)
# Hardware efficient layers
layer_size = n_qubits * 2 # RY and RZ for each qubit
n_layers = len(params) // layer_size
for layer in range(n_layers):
for i in range(n_qubits):
qml.RY(params[layer * layer_size + i], wires=i)
qml.RZ(params[layer * layer_size + n_qubits + i], wires=i)
for i in range(n_qubits - 1):
qml.CNOT(wires=[i, i + 1])
# Choose ansatz
if ansatz_type == "hardware_efficient":
ansatz = hardware_efficient_ansatz
n_params = n_qubits * 4 # 2 layers, 2 params per qubit per layer
else:
ansatz = basic_ansatz
n_params = n_qubits
@qml.qnode(dev)
def classifier_circuit(x, params):
ansatz(x, params)
return qml.expval(qml.PauliZ(0))
# Initialize parameters
params = pnp.random.uniform(0, 2 * pnp.pi, n_params, requires_grad=True)
# Cost function
def cost_fn(params):
predictions = pnp.array([classifier_circuit(x, params) for x in X_train])
# Convert labels to {-1, 1} format
target = 2 * y_train - 1
# Squared loss
loss = pnp.mean((predictions - target) ** 2)
return loss
# Training
if optimizer == "adam":
opt = qml.AdamOptimizer(stepsize=0.1)
else:
opt = qml.GradientDescentOptimizer(stepsize=0.1)
costs = []
for iteration in range(max_iterations):
params, cost = opt.step_and_cost(cost_fn, params)
costs.append(float(cost))
if iteration % 20 == 0:
logger.info(f"Iteration {iteration}: Cost = {cost:.4f}")
# Early stopping
if iteration > 10 and abs(costs[-1] - costs[-10]) < 1e-6:
break
# Test predictions
test_predictions = []
test_scores = []
for x in X_test:
score = classifier_circuit(x, params)
prediction = 1 if score > 0 else 0
test_predictions.append(prediction)
test_scores.append(float(score))
# Training accuracy
train_predictions = []
for x in X_train:
score = classifier_circuit(x, params)
prediction = 1 if score > 0 else 0
train_predictions.append(prediction)
train_accuracy = np.mean(np.array(train_predictions) == y_train)
return {
'success': True,
'ansatz_type': ansatz_type,
'n_qubits': n_qubits,
'n_parameters': n_params,
'training_samples': len(X_train),
'test_samples': len(X_test),
'train_accuracy': float(train_accuracy),
'final_cost': float(costs[-1]),
'cost_history': costs,
'test_predictions': test_predictions,
'test_scores': test_scores,
'optimal_parameters': params.tolist(),
'iterations': len(costs)
}
except Exception as e:
logger.error(f"Error in variational classifier: {e}")
return {'success': False, 'error': str(e)}
async def quantum_kernel_method(
training_data: List[List[float]],
training_labels: List[int],
test_data: List[List[float]],
kernel_type: str = "basic",
gamma: float = 1.0
) -> Dict[str, Any]:
"""
Implement quantum kernel methods for classification.
Args:
training_data: Training feature vectors
training_labels: Training labels
test_data: Test feature vectors
kernel_type: Type of quantum kernel
gamma: Kernel parameter
Returns:
Quantum kernel classification results
"""
logger.info(f"Running quantum kernel method with {kernel_type} kernel")
try:
import pennylane as qml
from pennylane import numpy as pnp
X_train = np.array(training_data)
y_train = np.array(training_labels)
X_test = np.array(test_data)
n_features = X_train.shape[1]
n_qubits = min(n_features, 4) # Limit for simulation
# Adjust feature dimension
if n_features > n_qubits:
X_train = X_train[:, :n_qubits]
X_test = X_test[:, :n_qubits]
# Normalize
X_train = X_train / (np.linalg.norm(X_train, axis=1, keepdims=True) + 1e-8)
X_test = X_test / (np.linalg.norm(X_test, axis=1, keepdims=True) + 1e-8)
dev = qml.device('default.qubit', wires=n_qubits)
def feature_map(x):
"""Quantum feature map."""
if kernel_type == "basic":
for i in range(n_qubits):
qml.RY(x[i] * np.pi, wires=i)
for i in range(n_qubits - 1):
qml.CNOT(wires=[i, i + 1])
elif kernel_type == "pauli":
# Pauli feature map
for i in range(n_qubits):
qml.RY(x[i] * np.pi, wires=i)
for i in range(n_qubits):
for j in range(i + 1, n_qubits):
qml.CNOT(wires=[i, j])
qml.RZ(x[i] * x[j] * gamma, wires=j)
qml.CNOT(wires=[i, j])
else:
# Default feature map
for i in range(n_qubits):
qml.RY(x[i] * np.pi, wires=i)
@qml.qnode(dev)
def kernel_circuit(x1, x2):
\"\"\"Compute quantum kernel between two data points.\"\"\"\n feature_map(x1)\n qml.adjoint(feature_map)(x2)\n return qml.probs(wires=range(n_qubits))\n \n def quantum_kernel(x1, x2):\n \"\"\"Quantum kernel function.\"\"\"\n probs = kernel_circuit(x1, x2)\n # Kernel is the probability of measuring |0...0⟩\n return probs[0]\n \n # Compute kernel matrix\n logger.info(\"Computing kernel matrix...\")\n n_train = len(X_train)\n n_test = len(X_test)\n \n K_train = np.zeros((n_train, n_train))\n for i in range(n_train):\n for j in range(i, n_train):\n k_val = quantum_kernel(X_train[i], X_train[j])\n K_train[i, j] = k_val\n K_train[j, i] = k_val # Kernel is symmetric\n \n K_test = np.zeros((n_test, n_train))\n for i in range(n_test):\n for j in range(n_train):\n K_test[i, j] = quantum_kernel(X_test[i], X_train[j])\n \n # Solve kernel ridge regression\n # K * alpha = y\n regularization = 1e-6\n K_reg = K_train + regularization * np.eye(n_train)\n \n try:\n alpha = np.linalg.solve(K_reg, y_train)\n except np.linalg.LinAlgError:\n # Fallback to pseudo-inverse\n alpha = np.linalg.pinv(K_reg) @ y_train\n \n # Make predictions\n test_predictions = K_test @ alpha\n test_classes = (test_predictions > 0.5).astype(int)\n \n # Training predictions\n train_predictions = K_train @ alpha\n train_classes = (train_predictions > 0.5).astype(int)\n train_accuracy = np.mean(train_classes == y_train)\n \n return {\n 'success': True,\n 'kernel_type': kernel_type,\n 'n_qubits': n_qubits,\n 'training_samples': n_train,\n 'test_samples': n_test,\n 'train_accuracy': float(train_accuracy),\n 'test_predictions': test_classes.tolist(),\n 'test_scores': test_predictions.tolist(),\n 'kernel_matrix_rank': np.linalg.matrix_rank(K_train),\n 'kernel_trace': float(np.trace(K_train))\n }\n \n except Exception as e:\n logger.error(f\"Error in quantum kernel method: {e}\")\n return {'success': False, 'error': str(e)}\n\nasync def quantum_generative_model(\n training_data: List[List[float]],\n n_qubits: int = 4,\n n_layers: int = 3,\n learning_rate: float = 0.1,\n epochs: int = 100\n) -> Dict[str, Any]:\n \"\"\"\n Train a quantum generative model.\n \n Args:\n training_data: Training data samples\n n_qubits: Number of qubits\n n_layers: Number of layers in generator\n learning_rate: Learning rate\n epochs: Training epochs\n \n Returns:\n Generative model results\n \"\"\"\n logger.info(f\"Training quantum generative model with {n_qubits} qubits\")\n \n try:\n import pennylane as qml\n from pennylane import numpy as pnp\n \n X_train = np.array(training_data)\n n_samples, n_features = X_train.shape\n \n # Limit features to n_qubits\n if n_features > n_qubits:\n X_train = X_train[:, :n_qubits]\n n_features = n_qubits\n \n # Normalize to [0, 1]\n X_train = (X_train - X_train.min()) / (X_train.max() - X_train.min() + 1e-8)\n \n dev = qml.device('default.qubit', wires=n_qubits)\n \n def generator_circuit(params):\n \"\"\"Quantum generator circuit.\"\"\"\n # Initialize in superposition\n for i in range(n_qubits):\n qml.Hadamard(wires=i)\n \n # Variational layers\n for layer in range(n_layers):\n for i in range(n_qubits):\n qml.RY(params[layer * n_qubits * 2 + i], wires=i)\n qml.RZ(params[layer * n_qubits * 2 + n_qubits + i], wires=i)\n \n for i in range(n_qubits - 1):\n qml.CNOT(wires=[i, i + 1])\n \n @qml.qnode(dev)\n def generate_sample(params):\n generator_circuit(params)\n return qml.probs(wires=range(n_features))\n \n # Initialize parameters\n n_params = n_layers * n_qubits * 2\n params = pnp.random.uniform(0, 2 * pnp.pi, n_params, requires_grad=True)\n \n def target_distribution(x):\n \"\"\"Target distribution based on training data.\"\"\"\n # Empirical distribution\n closest_idx = np.argmin(np.sum((X_train - x)**2, axis=1))\n return 1.0 / n_samples # Uniform over training samples\n \n def kl_divergence_loss(params):\n \"\"\"KL divergence between generated and target distributions.\"\"\"\n generated_probs = generate_sample(params)\n \n # Calculate empirical target probabilities\n n_states = 2**n_features\n target_probs = np.zeros(n_states)\n \n for sample in X_train:\n # Convert continuous sample to discrete state\n state_idx = 0\n for i, val in enumerate(sample[:n_features]):\n if val > 0.5:\n state_idx += 2**i\n target_probs[state_idx] += 1.0 / n_samples\n \n # Add small epsilon to avoid log(0)\n epsilon = 1e-8\n target_probs += epsilon\n generated_probs += epsilon\n \n # Normalize\n target_probs /= np.sum(target_probs)\n generated_probs /= np.sum(generated_probs)\n \n # KL divergence\n kl_div = np.sum(target_probs * np.log(target_probs / generated_probs))\n return kl_div\n \n # Training loop\n optimizer = qml.AdamOptimizer(stepsize=learning_rate)\n losses = []\n \n for epoch in range(epochs):\n params, loss = optimizer.step_and_cost(kl_divergence_loss, params)\n losses.append(float(loss))\n \n if epoch % 20 == 0:\n logger.info(f\"Epoch {epoch}: Loss = {loss:.4f}\")\n \n # Generate samples\n generated_probs = generate_sample(params)\n \n # Sample from the learned distribution\n n_generate = min(50, n_samples)\n generated_samples = []\n \n for _ in range(n_generate):\n # Sample a quantum state\n state_idx = np.random.choice(len(generated_probs), p=generated_probs)\n \n # Convert state index to binary representation\n binary = format(state_idx, f'0{n_features}b')\n sample = [int(bit) for bit in binary]\n generated_samples.append(sample)\n \n return {\n 'success': True,\n 'n_qubits': n_qubits,\n 'n_layers': n_layers,\n 'epochs': epochs,\n 'final_loss': float(losses[-1]),\n 'loss_history': losses,\n 'generated_samples': generated_samples,\n 'generated_probabilities': generated_probs.tolist(),\n 'training_samples': len(X_train),\n 'optimal_parameters': params.tolist()\n }\n \n except Exception as e:\n logger.error(f\"Error in quantum generative model: {e}\")\n return {'success': False, 'error': str(e)}"