text: A 2014 experiment conducted by Gabriela Barreto Lemos used this phenomenon to create images of cats.
full_question: A 2014 experiment conducted by Gabriela Barreto Lemos used this phenomenon to create images of cats. It occurs when one of the eigenvalues of the joint density matrix's partial transpose is negative, a criterion named for Peres and Horodecki. The entropy of this phenomenon is given by the Von Neumann entropy for one of its reduced density matrices. The CHSH inequality can be used to prove a theorem holding that the effects of this phenomenon cannot be explained by local hidden variable theories, because it violates Bell's inequality. A thought experiment using this phenomenon led to the conclusion that quantum mechanics is an incomplete theory, according to the EPR paradox. For 10 points, name this phenomenon in which the states of two spatially separated particles are intrinsically related.
first_sentence: A 2014 experiment conducted by Gabriela Barreto Lemos used this phenomenon to create images of cats.
raw_answer: quantum entanglement [prompt on "spooky action at a distance"]