• Simulation = software implementation of a mathematical model

• Why? Study algorithms, experiment with parameters and noise

• Advantages: see all state amplitudes, probabilities, entanglement

• Disadvantage: need O(2ⁿ) space and time for n qubits

  Simulation limit: n ≈ 30 on single node, n ≈ 50 distributed on 65000 nodes

• Pure states (state vector) vs. mixed states (density matrix) vs. unentangled (separable)