Entanglement entropy is one of the most important measures of quantum entanglement. Can entanglement entropy be measured in experiments? Is entanglement entropy related to some experimentally accessible observables? Here I will discuss a mathematical relation between quantum noise and entanglement entropy, known as the Klich-Levitov formula [1]. After a brief introduction to entanglement entropy and full counting statistics [2], I will prove the Klich-Levitov formula following Ref. [1]. I will then apply the Klich-Levitov formula to a simple quantum tunneling process and compute the entropy production in such a process.

Reference:

- Israel Klich and Leonid Levitov, "
*Quantum Noise as an Entanglement Meter*", Phys. Rev. Lett.**102**, 100502 (2009). - L. S. Levitov and G. B. Lesovik, "Charge distribution in quantum shot noise", JETP Lett.
**58**, 230 (1993). Translated from Pis'ma Zh. Eksp. Teor. Fiz.**58,**225 (1993).