Example Concept: Quantum error correction uses redundancy by encoding a logical qubit into multiple physical qubits to detect and correct errors without directly measuring the quantum state. This is achieved by using stabilizer codes, which involve measuring a set of operators that commute with the logical qubit's state, allowing for error detection and correction without collapsing the superposition. Unlike classical codes, QEC must preserve quantum coherence and entanglement, making it more complex but essential for reliable quantum computation.