Create grover_circuit.py

quantum/circuits/grover_circuit.py

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+# grover_circuit.py
+import numpy as np
+from qiskit import QuantumCircuit, Aer, execute
+from qiskit.visualization import plot_histogram
+from qiskit.quantum_info import Statevector
+
+def create_grover_circuit(num_qubits, marked_element):
+    """
+    Create a quantum circuit for Grover's algorithm.
+    
+    Parameters:
+    - num_qubits: Number of qubits in the circuit
+    - marked_element: The index of the marked element to search for (0 to 2^num_qubits - 1)
+    
+    Returns:
+    - QuantumCircuit: The constructed Grover's algorithm circuit
+    """
+    circuit = QuantumCircuit(num_qubits, num_qubits)
+
+    # Initialize qubits in superposition
+    circuit.h(range(num_qubits))
+
+    # Grover's iterations
+    num_iterations = int(np.pi / 4 * np.sqrt(2**num_qubits))  # Optimal number of iterations
+    for _ in range(num_iterations):
+        # Oracle: Flip the sign of the marked element
+        circuit.x(marked_element)
+        circuit.h(marked_element)
+        circuit.z(marked_element)
+        circuit.h(marked_element)
+        circuit.x(marked_element)
+
+        # Diffusion operator
+        circuit.h(range(num_qubits))
+        circuit.x(range(num_qubits))
+        circuit.h(num_qubits - 1)
+        circuit.cx(range(num_qubits - 1), num_qubits - 1)
+        circuit.h(num_qubits - 1)
+        circuit.x(range(num_qubits))
+        circuit.h(range(num_qubits))
+
+    # Measure the qubits
+    circuit.measure(range(num_qubits), range(num_qubits))
+
+    return circuit
+
+def run_grover_simulation(num_qubits, marked_element):
+    """
+    Run the Grover's algorithm simulation and return the results.
+    
+    Parameters:
+    - num_qubits: Number of qubits in the circuit
+    - marked_element: The index of the marked element to search for
+    
+    Returns:
+    - counts: Measurement results
+    - statevector: State vector of the quantum system
+    """
+    # Create the Grover circuit
+    circuit = create_grover_circuit(num_qubits, marked_element)
+
+    # Use the Aer's qasm_simulator
+    simulator = Aer.get_backend('qasm_simulator')
+
+    # Execute the circuit on the qasm simulator
+    job = execute(circuit, simulator, shots=1024)
+    result = job.result()
+
+    # Get measurement counts
+    counts = result.get_counts(circuit)
+
+    # Get the state vector for visualization
+    statevector = Statevector.from_dict(counts)
+
+    return counts, statevector
+
+def visualize_results(counts):
+    """
+    Visualize the results of the Grover's algorithm simulation.
+    
+    Parameters:
+    - counts: Measurement results
+    """
+    print("Counts:", counts)
+    plot_histogram(counts).show()
+
+if __name__ == "__main__":
+    num_qubits = 3  # Number of qubits (for 8 possible elements)
+    marked_element = 5  # The index of the marked element (e.g., 5)
+
+    # Run the Grover simulation
+    counts, statevector = run_grover_simulation(num_qubits, marked_element)
+
+    # Visualize the results
+    visualize_results(counts)