Many proposals exist for the implementation of quantum error correction. A popular approach is to compute with sets of entangled physical qubits, called 鈥渓ogical qubits鈥�, that enable the detection and correction of errors without breaking quantum physics鈥� rules about measurement and how it affects systems.
Copying quantum information is not possible due to the no cloning theorem. In classical computers, error correction often employs redundancy: for example, if you duplicate each bit 10 times then it is easy to detect and correct a single bit flip. To get around the no cloning theorem in quantum error correction you can spread the (logical) information of one logical qubit onto a highly entangled state of several (physical) qubits. .
Working with entangled units of qubits also allows one to circumvent quantum mechanics鈥� measurement problem: when a qubit is measured, its delicate quantum information is collapsed into a specific state and the richness of information is lost, therefore, one must measure the errors and not the qubits themselves.