Fixed the examples

Author: stephen2ml

examples/module1_fundamentals/02_quantum_gates_circuits.py

@@ -137,27 +137,59 @@ def visualize_gate_effects(single_qubit_circuits):
     print("=== GATE EFFECTS VISUALIZATION ===")
     print()
 
-    # Create Bloch sphere plots
-    n_gates = len(single_qubit_circuits)
-    fig, axes = plt.subplots(1, n_gates, figsize=(3*n_gates, 3))
-    if n_gates == 1:
-        axes = [axes]
-    
+    # Create individual Bloch sphere plots for each gate
     for i, (gate_name, circuit) in enumerate(single_qubit_circuits.items()):
         state = Statevector.from_instruction(circuit)
 
-        ax = axes[i]
-        # plot_bloch_multivector no longer accepts ax parameter in Qiskit 2.x
+        print(f"{gate_name}:")
+        print(f"  State vector: {state}")
+        print(f"  Probabilities: |0⟩: {abs(state[0])**2:.3f}, |1⟩: {abs(state[1])**2:.3f}")
+        
+        # Create individual Bloch sphere plots
         try:
-            bloch_fig = plot_bloch_multivector(state, title="Qubit State")
-            # Save individual figure instead of using subplot
+            bloch_fig = plot_bloch_multivector(state, title=f"{gate_name} - Qubit State")
+            plt.savefig(f'module1_02_bloch_{i+1}.png', dpi=300, bbox_inches='tight')
+            plt.show()
         except Exception as e:
-            print(f"⚠️ Could not create Bloch sphere: {e}")
-        ax.set_title(gate_name, fontsize=10, pad=10)
+            print(f"⚠️ Could not create Bloch sphere for {gate_name}: {e}")
+            # Provide alternative visualization information
+            print(f"  Alternative: State components - α=({state[0].real:.3f}+{state[0].imag:.3f}i), β=({state[1].real:.3f}+{state[1].imag:.3f}i)")
+        
+        print()
 
-    plt.tight_layout()
-    plt.savefig('module1_02_gate_effects.png', dpi=300, bbox_inches='tight')
-    plt.show()
+    # Create a summary visualization with state information
+    try:
+        fig, ax = plt.subplots(1, 1, figsize=(12, 8))
+        
+        gate_names = list(single_qubit_circuits.keys())
+        prob_0 = []
+        prob_1 = []
+        
+        for gate_name, circuit in single_qubit_circuits.items():
+            state = Statevector.from_instruction(circuit)
+            prob_0.append(abs(state[0])**2)
+            prob_1.append(abs(state[1])**2)
+        
+        x = range(len(gate_names))
+        width = 0.35
+        
+        ax.bar([i - width/2 for i in x], prob_0, width, label='|0⟩ probability', alpha=0.8)
+        ax.bar([i + width/2 for i in x], prob_1, width, label='|1⟩ probability', alpha=0.8)
+        
+        ax.set_xlabel('Quantum Gates')
+        ax.set_ylabel('Probability')
+        ax.set_title('Gate Effects: Measurement Probabilities')
+        ax.set_xticks(x)
+        ax.set_xticklabels(gate_names, rotation=45, ha='right')
+        ax.legend()
+        ax.grid(True, alpha=0.3)
+        
+        plt.tight_layout()
+        plt.savefig('module1_02_gate_effects.png', dpi=300, bbox_inches='tight')
+        plt.show()
+        
+    except Exception as e:
+        print(f"⚠️ Could not create gate effects summary: {e}")
 
 
 def create_quantum_circuit_examples():
@@ -193,25 +225,49 @@ def create_quantum_circuit_examples():
     qc3.h(0)
     circuits['Circuit 3: GHZ preparation'] = qc3
 
-    # Display circuit diagrams
-    fig, axes = plt.subplots(len(circuits), 1, figsize=(12, 3*len(circuits)))
-    if len(circuits) == 1:
-        axes = [axes]
-    
+    # Display circuit information and create diagrams
     for i, (name, circuit) in enumerate(circuits.items()):
         print(f"{name}:")
         print(f"  Depth: {circuit.depth()}")
         print(f"  Gates: {circuit.count_ops()}")
 
-        # Draw circuit
-        circuit_drawer(circuit, output='mpl', ax=axes[i], style={'backgroundcolor': '#EEEEEE'})
-        axes[i].set_title(f'{name} (Depth: {circuit.depth()})', fontsize=12, pad=20)
+        # Draw circuit - create individual figures to avoid ax parameter issues
+        try:
+            fig = circuit.draw(output='mpl', style={'backgroundcolor': '#EEEEEE'})
+            fig.suptitle(f'{name} (Depth: {circuit.depth()})', fontsize=12)
+            # Save individual circuit diagrams
+            plt.figure(fig.number)
+            plt.savefig(f'module1_02_circuit_{i+1}.png', dpi=300, bbox_inches='tight')
+            plt.show()
+        except Exception as e:
+            print(f"⚠️ Could not create circuit diagram: {e}")
+            print(f"  Circuit structure: {circuit.data}")
 
         print()
 
-    plt.tight_layout()
-    plt.savefig('module1_02_circuit_examples.png', dpi=300, bbox_inches='tight')
-    plt.show()
+    # Create combined figure with all circuits
+    try:
+        fig, axes = plt.subplots(len(circuits), 1, figsize=(12, 3*len(circuits)))
+        if len(circuits) == 1:
+            axes = [axes]
+        
+        for i, (name, circuit) in enumerate(circuits.items()):
+            # Use text representation instead of circuit_drawer with ax parameter
+            axes[i].text(0.5, 0.5, f'{name}\nDepth: {circuit.depth()}\nGates: {circuit.count_ops()}', 
+                        ha='center', va='center', transform=axes[i].transAxes, 
+                        fontsize=10, bbox=dict(boxstyle="round,pad=0.3", facecolor="lightgray"))
+            axes[i].set_xlim(0, 1)
+            axes[i].set_ylim(0, 1)
+            axes[i].set_xticks([])
+            axes[i].set_yticks([])
+            axes[i].set_title(f'{name} (Depth: {circuit.depth()})', fontsize=12, pad=20)
+        
+        plt.tight_layout()
+        plt.savefig('module1_02_circuit_examples.png', dpi=300, bbox_inches='tight')
+        plt.show()
+        
+    except Exception as e:
+        print(f"⚠️ Could not create combined circuit diagram: {e}")
 
     return circuits
 

examples/module1_fundamentals/07_no_cloning_theorem.py

@@ -25,7 +25,18 @@
 import matplotlib.pyplot as plt
 from qiskit import QuantumCircuit, ClassicalRegister, transpile
 from qiskit.visualization import plot_bloch_multivector, plot_histogram
-from qiskit.quantum_info import Statevector, random_statevector, fidelity
+from qiskit.quantum_info import Statevector, random_statevector
+# Handle different Qiskit versions for fidelity
+try:
+    from qiskit.quantum_info import fidelity
+except ImportError:
+    # For older Qiskit versions, use state_fidelity
+    try:
+        from qiskit.quantum_info import state_fidelity as fidelity
+    except ImportError:
+        # Fallback implementation
+        def fidelity(state1, state2):
+            return abs(np.vdot(state1.data, state2.data))**2
 from qiskit_aer import AerSimulator
 import sys
 from pathlib import Path

examples/module3_programming/06_quantum_debugging_guide.py

@@ -22,7 +22,18 @@
 import matplotlib.pyplot as plt
 from qiskit import QuantumCircuit, ClassicalRegister, transpile
 from qiskit.visualization import plot_histogram, plot_bloch_multivector
-from qiskit.quantum_info import Statevector, DensityMatrix, fidelity
+from qiskit.quantum_info import Statevector, DensityMatrix
+# Handle different Qiskit versions for fidelity
+try:
+    from qiskit.quantum_info import fidelity
+except ImportError:
+    # For older Qiskit versions, use state_fidelity
+    try:
+        from qiskit.quantum_info import state_fidelity as fidelity
+    except ImportError:
+        # Fallback implementation
+        def fidelity(state1, state2):
+            return abs(np.vdot(state1.data, state2.data))**2
 from qiskit_aer import AerSimulator
 import warnings
 import sys

examples/module6_machine_learning/03_quantum_neural_networks.py

@@ -12,7 +12,22 @@
 from qiskit import QuantumCircuit, ClassicalRegister, ClassicalRegister
 from qiskit.quantum_info import Statevector
 from qiskit_aer import AerSimulator
-from sklearn.datasets import make_regression, make_classification, load_boston
+# Handle sklearn dataset changes
+from sklearn.datasets import make_regression, make_classification
+try:
+    from sklearn.datasets import load_boston
+except ImportError:
+    # Boston dataset removed in sklearn 1.2+, create alternative
+    def load_boston():
+        print("ℹ️  Boston housing dataset removed from sklearn, using synthetic regression data")
+        X, y = make_regression(n_samples=506, n_features=13, noise=10, random_state=42)
+        # Return in format similar to original boston dataset
+        return type('Dataset', (), {
+            'data': X,
+            'target': y,
+            'feature_names': [f'feature_{i}' for i in range(13)],
+            'DESCR': 'Synthetic regression dataset (replacing Boston housing)'
+        })()
 from sklearn.preprocessing import StandardScaler
 from sklearn.model_selection import train_test_split
 from sklearn.metrics import mean_squared_error, accuracy_score

examples/module7_hardware/04_real_hardware_errors.py

@@ -11,7 +11,22 @@
 import argparse
 from qiskit import QuantumCircuit, ClassicalRegister, transpile, QuantumRegister, ClassicalRegister
 from qiskit_aer import AerSimulator
-from qiskit_aer.noise import NoiseModel, depolarizing_error, thermal_relaxation_error, readout_error
+# Handle different Qiskit Aer versions for noise models
+try:
+    from qiskit_aer.noise import NoiseModel, depolarizing_error, thermal_relaxation_error, readout_error
+except ImportError:
+    try:
+        from qiskit_aer.noise import NoiseModel, depolarizing_error, thermal_relaxation_error
+        from qiskit_aer.noise import ReadoutError as readout_error
+    except ImportError:
+        try:
+            from qiskit_aer.noise import NoiseModel, depolarizing_error, thermal_relaxation_error
+            # Create a simple readout error class for compatibility
+            def readout_error(probabilities):
+                from qiskit_aer.noise import ReadoutError
+                return ReadoutError(probabilities)
+        except ImportError:
+            print("ℹ️  Noise models not fully available, using simplified simulation")
 from qiskit.quantum_info import state_fidelity, process_fidelity, Statevector
 from qiskit.result import marginal_counts
 from qiskit.circuit.library import XGate, HGate, CXGate

examples/module8_applications/01_quantum_chemistry_drug_discovery.py

@@ -13,7 +13,17 @@
 from qiskit.circuit.library import TwoLocal, EfficientSU2
 from qiskit_aer import AerSimulator
 from qiskit.quantum_info import SparsePauliOp, Statevector
-from qiskit.algorithms.optimizers import SPSA, COBYLA
+# Handle different Qiskit versions for algorithms
+try:
+    from qiskit.algorithms.optimizers import SPSA, COBYLA
+except ImportError:
+    try:
+        from qiskit_algorithms.optimizers import SPSA, COBYLA
+    except ImportError:
+        # Fallback: use scipy optimizers only
+        print("ℹ️  Qiskit optimizers not available, using scipy.optimize only")
+        SPSA = None
+        COBYLA = None
 from scipy.optimize import minimize
 from scipy.spatial.distance import cdist
 import json

examples/module8_applications/02_financial_portfolio_optimization.py

@@ -13,7 +13,17 @@
 from qiskit.circuit.library import QAOAAnsatz
 from qiskit_aer import AerSimulator
 from qiskit.quantum_info import SparsePauliOp
-from qiskit.algorithms.optimizers import COBYLA, SPSA
+# Handle different Qiskit versions for algorithms
+try:
+    from qiskit.algorithms.optimizers import COBYLA, SPSA
+except ImportError:
+    try:
+        from qiskit_algorithms.optimizers import COBYLA, SPSA
+    except ImportError:
+        # Fallback: use scipy optimizers only
+        print("ℹ️  Qiskit optimizers not available, using scipy.optimize only")
+        COBYLA = None
+        SPSA = None
 from scipy.optimize import minimize
 import pandas as pd
 import yfinance as yf

examples/module8_applications/05_materials_science_manufacturing.py

@@ -13,7 +13,17 @@
 from qiskit.circuit.library import TwoLocal, EfficientSU2
 from qiskit_aer import AerSimulator
 from qiskit.quantum_info import SparsePauliOp, Statevector
-from qiskit.algorithms.optimizers import SPSA, COBYLA
+# Handle different Qiskit versions for algorithms
+try:
+    from qiskit.algorithms.optimizers import SPSA, COBYLA
+except ImportError:
+    try:
+        from qiskit_algorithms.optimizers import SPSA, COBYLA
+    except ImportError:
+        # Fallback: use scipy optimizers only
+        print("ℹ️  Qiskit optimizers not available, using scipy.optimize only")
+        SPSA = None
+        COBYLA = None
 from scipy.optimize import minimize
 from scipy.spatial.distance import cdist
 import pandas as pd