ibm_quantum_simple.py

#!/usr/bin/env python3
"""
IBM Quantum Integration Simplificada - Simulador Cuantico
Version simplificada que funciona sin dependencias complejas
"""

import os
import time
import json
from typing import Dict, List, Optional, Tuple
import numpy as np

# Verificar disponibilidad de Qiskit
QISKIT_AVAILABLE = False
QuantumCircuit = None
transpile = None
IBMProvider = None

try:
    from qiskit import QuantumCircuit, transpile
    from qiskit_ibm_provider import IBMProvider
    QISKIT_AVAILABLE = True
    print("Qiskit disponible")
except ImportError as e:
    QISKIT_AVAILABLE = False
    print(f"Qiskit no disponible: {e}")

class IBMQuantumSimulatorSimple:
    """Simulador cuantico simplificado con IBM Quantum"""
    
    def __init__(self, api_token: Optional[str] = None):
        self.api_token = api_token or os.getenv('IBM_QUANTUM_TOKEN')
        self.provider = None
        self.backend = None
        self.available_backends = []
        
        if QISKIT_AVAILABLE and self.api_token:
            self._initialize_ibm_quantum()
        else:
            print("IBM Quantum no configurado. Usando simulador local.")
    
    def _initialize_ibm_quantum(self):
        """Inicializa la conexion con IBM Quantum"""
        try:
            print("Conectando a IBM Quantum...")
            
            # Guardar token si se proporciona
            if self.api_token:
                IBMProvider.save_account(token=self.api_token, overwrite=True)
                print("Token guardado")
            
            # Conectar a IBM Quantum
            self.provider = IBMProvider()
            self.available_backends = self.provider.backends()
            
            print(f"Conectado a IBM Quantum. Backends: {len(self.available_backends)}")
            
            # Seleccionar el mejor backend disponible
            self._select_best_backend()
            
        except Exception as e:
            print(f"Error conectando a IBM Quantum: {e}")
            self.provider = None
    
    def _select_best_backend(self):
        """Selecciona el mejor backend disponible"""
        if not self.available_backends:
            return
        
        # Priorizar backends reales sobre simuladores
        real_backends = [b for b in self.available_backends if not b.configuration().simulator]
        sim_backends = [b for b in self.available_backends if b.configuration().simulator]
        
        if real_backends:
            # Seleccionar el backend real con menos cola
            self.backend = min(real_backends, key=lambda b: b.status().pending_jobs)
            print(f"Usando hardware cuantico real: {self.backend.name}")
        else:
            # Usar simulador si no hay hardware disponible
            self.backend = min(sim_backends, key=lambda b: b.configuration().n_qubits)
            print(f"Usando simulador: {self.backend.name}")
    
    def simulate_molecule_ibm(self, molecule_name: str, parameters: Dict = None) -> Dict:
        """Simula una molecula usando IBM Quantum"""
        if not QISKIT_AVAILABLE:
            return self._fallback_simulation(molecule_name, parameters)
        
        try:
            # Crear circuito cuantico simple
            circuit = self._create_simple_circuit()
            
            # Ejecutar en IBM Quantum
            if self.backend and self.provider:
                result = self._execute_on_ibm_quantum(circuit)
            else:
                result = self._execute_local_simulation(circuit)
            
            return {
                'energy': result['energy'],
                'interaction_strength': self._classify_interaction(result['energy']),
                'computation_time': result['computation_time'],
                'molecule': molecule_name,
                'backend_used': result.get('backend', 'local'),
                'status': 'success',
                'quantum_circuit_depth': result.get('circuit_depth', 0),
                'shots': result.get('shots', 1024)
            }
            
        except Exception as e:
            print(f"Error en simulacion IBM Quantum: {e}")
            return self._fallback_simulation(molecule_name, parameters)
    
    def _create_simple_circuit(self):
        """Crea circuito cuantico simple"""
        circuit = QuantumCircuit(4, 4)
        
        # Aplicar puertas cuanticas basicas
        circuit.h(0)
        circuit.cx(0, 1)
        circuit.cx(1, 2)
        circuit.cx(2, 3)
        circuit.ry(np.pi/4, 0)
        circuit.rz(np.pi/8, 1)
        
        circuit.measure_all()
        return circuit
    
    def _execute_on_ibm_quantum(self, circuit) -> Dict:
        """Ejecuta circuito en IBM Quantum"""
        start_time = time.time()
        
        try:
            # Transpilar circuito para el backend
            transpiled_circuit = transpile(circuit, self.backend)
            
            # Ejecutar trabajo
            job = self.backend.run(transpiled_circuit, shots=1024)
            
            # Esperar resultados
            result = job.result()
            counts = result.get_counts()
            
            # Calcular energia (simulacion basica)
            energy = self._calculate_energy_from_counts(counts)
            
            computation_time = time.time() - start_time
            
            return {
                'energy': energy,
                'computation_time': computation_time,
                'backend': self.backend.name,
                'circuit_depth': transpiled_circuit.depth(),
                'shots': 1024,
                'counts': counts
            }
            
        except Exception as e:
            print(f"Error ejecutando en IBM Quantum: {e}")
            return self._execute_local_simulation(circuit)
    
    def _execute_local_simulation(self, circuit) -> Dict:
        """Ejecuta simulacion local como fallback"""
        start_time = time.time()
        
        try:
            from qiskit import Aer
            simulator = Aer.get_backend('qasm_simulator')
            
            # Ejecutar simulacion
            job = simulator.run(transpiled_circuit, shots=1024)
            result = job.result()
            counts = result.get_counts()
            
            # Calcular energia
            energy = self._calculate_energy_from_counts(counts)
            
            computation_time = time.time() - start_time
            
            return {
                'energy': energy,
                'computation_time': computation_time,
                'backend': 'qasm_simulator',
                'circuit_depth': circuit.depth(),
                'shots': 1024,
                'counts': counts
            }
            
        except Exception as e:
            print(f"Error en simulacion local: {e}")
            return self._fallback_simulation('LiH', {})
    
    def _calculate_energy_from_counts(self, counts: Dict) -> float:
        """Calcula energia a partir de los resultados del circuito"""
        # Simulacion basica de energia
        total_shots = sum(counts.values())
        if total_shots == 0:
            return -1.0
        
        # Calcular energia basada en distribucion de estados
        energy = 0.0
        for state, count in counts.items():
            # Convertir estado binario a energia
            state_energy = -len(state) * 0.1  # Energia basica
            probability = count / total_shots
            energy += state_energy * probability
        
        return energy
    
    def _classify_interaction(self, energy: float) -> str:
        """Clasifica la fuerza de interaccion"""
        if energy < -2.0:
            return "muy_fuerte"
        elif energy < -1.5:
            return "fuerte"
        elif energy < -1.0:
            return "moderada"
        elif energy < -0.5:
            return "debil"
        else:
            return "muy_debil"
    
    def _fallback_simulation(self, molecule_name: str, parameters: Dict) -> Dict:
        """Simulacion de fallback cuando IBM Quantum no esta disponible"""
        from quantum_simulator import simulate_molecule
        return simulate_molecule(molecule_name, parameters)
    
    def get_available_backends(self) -> List[Dict]:
        """Obtiene lista de backends disponibles"""
        if not self.provider:
            return []
        
        backends_info = []
        for backend in self.available_backends:
            try:
                status = backend.status()
                config = backend.configuration()
                
                backends_info.append({
                    'name': backend.name,
                    'status': status.status_msg,
                    'pending_jobs': status.pending_jobs,
                    'n_qubits': config.n_qubits,
                    'simulator': config.simulator,
                    'operational': status.operational
                })
            except Exception as e:
                print(f"Error obteniendo info del backend {backend.name}: {e}")
                continue
        
        return backends_info
    
    def get_backend_status(self) -> Dict:
        """Obtiene estado del backend actual"""
        if not self.backend:
            return {'status': 'no_backend'}
        
        try:
            status = self.backend.status()
            return {
                'name': self.backend.name,
                'status': status.status_msg,
                'pending_jobs': status.pending_jobs,
                'operational': status.operational
            }
        except Exception as e:
            return {'status': 'error', 'error': str(e)}

# Instancia global
ibm_quantum_simulator = IBMQuantumSimulatorSimple()

def simulate_molecule_ibm(molecule: str, parameters: Dict = None, api_token: str = None) -> Dict:
    """Funcion de conveniencia para simulacion con IBM Quantum"""
    if api_token:
        simulator = IBMQuantumSimulatorSimple(api_token)
        return simulator.simulate_molecule_ibm(molecule, parameters)
    else:
        return ibm_quantum_simulator.simulate_molecule_ibm(molecule, parameters)

if __name__ == "__main__":
    # Prueba del simulador IBM Quantum
    print("Probando simulador IBM Quantum...")
    
    # Simular LiH
    result = simulate_molecule_ibm('LiH')
    print(f"Resultado LiH: {result}")
    
    # Obtener backends disponibles
    simulator = IBMQuantumSimulatorSimple()
    backends = simulator.get_available_backends()
    print(f"Backends disponibles: {len(backends)}")
    
    for backend in backends[:3]:  # Mostrar solo los primeros 3
        print(f"  - {backend['name']}: {backend['n_qubits']} qubits, {backend['status']}")