Yes, it is possible for three particles to be entangled. Entanglement is a fundamental concept in quantum mechanics that describes the correlation of quantum states between particles, resulting in nonclassical connections that cannot be explained by classical physics.
In the case of three particles, the entanglement can take various forms depending on the specific quantum states involved. One common scenario is known as tripartite entanglement, where all three particles are correlated with one another. The quantum state of the three-particle system cannot be expressed as a simple product of individual particle states but requires a more complex description that accounts for the entanglement.
Tripartite entanglement has been experimentally observed in various physical systems. For example, in quantum optics, entangled states of three photons have been generated and studied. In atomic physics, three atoms can be entangled through their interactions with one another or with an external field. Superconducting circuits, trapped ions, and other quantum systems have also been used to demonstrate tripartite entanglement.
The study of entanglement in multi-particle systems, including three or more particles, is an active area of research in quantum physics. Understanding and harnessing the properties of such complex entangled states can have implications for quantum information processing, quantum communication, and other quantum technologies.