The quantum vacuum in electromagnetic fields: From the Heisenberg-Euler effective action to vacuum birefringence

Understand

The focus of these lectures is on the quantum vacuum subjected to classical electromagnetic fields.

• To this end we explicitly derive the renowned Heisenberg-Euler effective action in constant electromagnetic fields in a rather pedagogical and easy to conceive way.
• As an application, we use it to study vacuum birefringence constituting one of the most promising optical signatures of quantum vacuum nonlinearity.