qiskit

Create a QuantumCircuit object, add gates like h() and cx(), then run it with AerSimulator and call result.get_counts() to retrieve measurement outcomes. A two-qubit Bell state requires only a Hadamard gate followed by a CNOT gate.

Install Qiskit with pip install qiskit, and add qiskit-aer for simulators and matplotlib for visualization. Python 3.8 or higher is required on Windows, macOS, or Linux.

Qiskit Aer provides a statevector simulator for exact state evolution, a QASM simulator for shot-based sampling, and a unitary simulator for matrix tracking. GPU acceleration is available for larger simulations.

Yes, Qiskit connects to IBM Quantum processors ranging from 5 to 127 qubits through cloud-based job submission. It supports job status tracking, result retrieval, and noise models derived from real hardware.

Qiskit supports realistic noise models including depolarizing, amplitude damping, and phase damping errors, plus gate and measurement errors. Custom error channels can be defined for simulation.

Classical simulation of quantum circuits scales exponentially with qubit count, so statevector simulation is practical only up to roughly 30 qubits depending on memory. Larger circuits require real quantum hardware or approximation methods.