Quantum systems maintain entanglement across qubits through a combination of physical isolation from the environment and the use of error correction techniques. Entanglement is a fundamental quantum property where the state of one qubit is dependent on the state of another, even when they are separated by large distances. To keep this fragile state intact, qubits must be shielded from external interference known as decoherence, which can cause entangled states to break down.
One common method to maintain entanglement is by using superconducting qubits, which operate at extremely low temperatures and are housed in a vacuum environment. This extreme isolation limits thermal noise and other external factors that could disrupt their states. Additionally, techniques like coupling qubits through a shared resonant cavity allow them to interact without direct contact, further preserving their entangled states. These techniques are critical in quantum computing setups, such as those developed by companies like IBM and Google.
Furthermore, researchers employ quantum error correction codes, which are designed to detect and correct errors that occur without measuring the qubits directly. These codes use additional physical qubits to store a logical qubit representation, which helps preserve entanglement even if one qubit experiences noise. For example, the surface code is a popular choice in quantum computing architectures as it can correct multiple errors in a scalable way. By combining isolation techniques and error correction, quantum systems can maintain entanglement across qubits, which is essential for effective quantum computation and communication.