29 October 2012
Quantum Correlation in Space and Time in

*Nature Physics*Quantum predictions challenge Einstein's theory of relativity

Prof. Antonio Acín collaborates in a new test that demonstrates how quantum predictions challenge Einstein’s theory of relativity.
Physicists have proposed a test that shows that it is impossible to explain quantum correlations as hidden influences propagating continuously and at arbitrary, yet finite, speed in space-time. ICREA Professor at ICFO, Antonio Acín collaborated in the proposal with an international team of researchers from Switzerland, Belgium, and Singapore. The paper, “Quantum nonlocality based on finite-speed causal influences leads to superluminal signaling\", which appears in Nature Physics, is based on what the researchers call a ‘hidden influence inequality’.

The implications of quantum theory have been troubling physicists since the theory was invented in the early 20th Century. The problem is that quantum theory predicts bizarre nonlocal behavior of particles – such as two ‘entangled’ particles which behave as one even when far apart. This seems to violate our sense of cause and effect in space and time.

\"The non-local correlations between quantum particles are a counterintuitive phenomenon, since they seem to involve an influence between particles that propagate faster than speed of light. In our study, we demonstrated that models where these influences spread with an arbitrary speed, although finite, could only reproduce quantum physics if they violated Einstein’s theory of relativity\" explains Dr. Acín.

The implications of quantum theory have been troubling physicists since the theory was invented in the early 20th Century. The problem is that quantum theory predicts bizarre nonlocal behavior of particles – such as two ‘entangled’ particles which behave as one even when far apart. This seems to violate our sense of cause and effect in space and time.

\"The non-local correlations between quantum particles are a counterintuitive phenomenon, since they seem to involve an influence between particles that propagate faster than speed of light. In our study, we demonstrated that models where these influences spread with an arbitrary speed, although finite, could only reproduce quantum physics if they violated Einstein’s theory of relativity\" explains Dr. Acín.