  Entanglement entropy, which is a measure of quantum correlations between
separate parts of a many-body system, has emerged recently as a fundamental
quantity in broad areas of theoretical physics, from cosmology and field theory
to condensed matter theory and quantum information. The universal appeal of the
entanglement entropy concept is related, in part, to the fact that it is
defined solely in terms of the many-body density matrix of the system, with no
relation to any particular observables. However, for the same reason, it has
not been clear how to access this quantity experimentally. Here we derive a
universal relation between entanglement entropy and the fluctuations of current
flowing through a quantum point contact (QPC) which opens a way to perform a
direct measurement of entanglement entropy. In particular, by utilizing
space-time duality of 1d systems, we relate electric noise generated by opening
and closing the QPC periodically in time with the seminal S = 1/3 log L
prediction of conformal field theory.
