How Does a Quantum Computer Process Information?

Classical computers use bits — each fixed at 0 or 1. Quantum computers use quantum bits (qubits), which exploit two quantum-mechanical phenomena: superposition (a qubit can represent 0 and 1 at the same time) and entanglement (qubits can be correlated so the state of one instantly influences another). Together, these allow a quantum computer to explore many possible solutions simultaneously. For specific problems — like factoring large numbers (Shor's algorithm) or searching databases (Grover's algorithm) — this provides an exponential speed-up. Current leading platforms use superconducting circuits (IBM, Google), trapped ions (IonQ, Quantinuum), or photonic systems. In 2019, Google's 53-qubit Sycamore processor performed a calculation in 200 seconds that would take a classical supercomputer an estimated 10,000 years.