Quantum entanglement is a phenomenon in quantum physics where two or more particles become connected in such a way that the state of one particle is instantly correlated with the state of the other, regardless of the distance between them. While this instantaneous correlation seems to violate the classical notion of causality, it does not allow for faster-than-light communication.
Quantum entanglement cannot be used to transmit information faster than the speed of light because the process of measuring the state of an entangled particle is random and unpredictable. This property is known as the no-communication theorem. Even though the entangled particles are correlated, there is no way to control the outcome of a measurement on one particle and use it to communicate information to the other entangled particle faster than the speed of light.
The random and unpredictable nature of quantum measurements prevents the use of entangled particles for faster-than-light communication. Any attempt to use them for such purposes would result in random and uncorrelated outcomes upon measurement, making reliable communication impossible.
So, while entangled particles can be used for secure quantum key distribution or other quantum information processing tasks, they do not provide a means for instantaneous communication over great distances. The speed of light remains the fundamental limit for transmitting information across vast distances in our current understanding of physics.