Understanding Quantum Entanglement and Non-Locality
Quantum entanglement occurs when two or more particles become linked such that the quantum state of each cannot be described independently, even when separated by vast distances. This demonstrates non-locality in particle physics by showing that measuring one particle instantly influences the state of its entangled partner, defying classical notions of locality where influences are limited by the speed of light.
Key Principles of Entanglement and Non-Locality
The principle stems from quantum superposition and the EPR paradox proposed by Einstein, Podolsky, and Rosen in 1935, who argued it implied 'spooky action at a distance.' Bell's theorem in 1964 provided a testable prediction: entangled particles violate local hidden variable theories, as confirmed by experiments measuring correlations that exceed classical limits.
A Practical Example: The Bell Test Experiment
In a typical Bell test, two entangled photons are sent to distant detectors. Measuring the polarization of one photon (e.g., horizontal or vertical) instantly determines the other's, regardless of separation. Experiments like those by Alain Aspect in 1982 showed correlation strengths violating Bell inequalities, proving non-local influences without direct communication.
Importance and Applications in Modern Physics
Non-locality via entanglement underpins quantum information science, enabling technologies like quantum cryptography and teleportation. It challenges our understanding of reality, supporting interpretations like the many-worlds theory, and drives research in quantum computing, where entangled qubits process information non-locally for exponential speedups.