Proving the existence of entangled particles outside the laboratory, as per the laws of quantum mechanics (QM), requires experimental verification and theoretical understanding. Here are some key aspects that contribute to the evidence for the existence of entangled particles in the broader context:
Bell's Inequality: One of the foundational experiments supporting the existence of entanglement is the Bell's inequality test. Proposed by physicist John Bell in the 1960s, this test provides a way to experimentally verify whether a system violates the principles of classical physics. Numerous experiments have been conducted, both in laboratory settings and in real-world scenarios, that demonstrate violations of Bell's inequality. These violations imply that entangled particles exist and exhibit correlations that cannot be explained by classical physics.
Quantum Information Processing: The development of quantum technologies, such as quantum computing, quantum cryptography, and quantum communication, relies on the principles of entanglement. These applications have been tested and implemented in various real-world scenarios. For example, quantum key distribution (QKD), a quantum cryptographic technique based on entanglement, has been successfully deployed in real-world networks to ensure secure communication over long distances.
Space-based Experiments: The field of quantum optics has seen significant advancements in satellite-based experiments. Satellites equipped with photon sources have been used to generate and distribute entangled photons over long distances. These experiments, such as the Chinese satellite Micius in the Quantum Experiments at Space Scale (QUESS) mission, have demonstrated entanglement between particles separated by several hundred kilometers. These achievements provide evidence that entanglement exists beyond the confines of a laboratory environment.
Fundamental Quantum Field Theory: The theoretical framework of quantum field theory, which unifies quantum mechanics and special relativity, incorporates the existence of entangled particles. The predictions and calculations based on this framework have been extensively tested and validated through experimental observations, supporting the fundamental principles of quantum mechanics.
While it may be challenging to directly observe entanglement in everyday situations due to the delicate nature of quantum states, the accumulated experimental evidence, technological applications, and theoretical consistency of quantum mechanics provide strong support for the existence of entangled particles outside the laboratory.