Quantum measurement outcomes are fundamentally random, making quantum computers perfect for generating true random numbers.

The Concept

Prepare a qubit in equal superposition using a Hadamard gate, then measure. Each measurement yields 0 or 1 with exactly 50% probability — genuine quantum randomness.

Implementation with Qiskit

from qiskit import QuantumCircuit
from qiskit_aer import AerSimulator

def quantum_random_bits(num_bits):
    circuit = QuantumCircuit(num_bits, num_bits)
    circuit.h(range(num_bits))  # Superposition
    circuit.measure(range(num_bits), range(num_bits))
    
    simulator = AerSimulator()
    result = simulator.run(circuit, shots=1).result()
    counts = result.get_counts()
    bitstring = list(counts.keys())[0]
    return bitstring

# Generate 8 random bits
random_value = quantum_random_bits(8)
print(f'Random byte: {random_value}')

Verification

Run the generator many times and verify the distribution is uniform. Classical PRNGs can pass statistical tests but are deterministic — only quantum measurement provides true randomness.