Measuring the Boiling Point of the Vacuum of Quantum Electrodynamics

Abstract

It is a long-standing non-trivial prediction of quantum electrodynamics that its vacuum is unstable in the background of a static, spatially uniform electric field and, in principle, sparks with spontaneous emission of electron-positron pairs. However, an experimental verification of this prediction seems out of reach because a sizeable rate for spontaneous pair production requires an extraordinarily strong electric field strength $|\mathbf{E}|$ of order the Schwinger critical field, ${\mathrm{E}}_c=m_e^2/e\simeq 1.3\times 10^{18}V/m$, where $m_e$ is the electron mass and $e$ is its charge. Here, we show that the measurement of the rate of pair production due to the decays of high-energy bremsstrahlung photons in a high-intensity laser field allows for the experimental determination of the Schwinger critical field and thus the boiling point of the vacuum of quantum electrodynamics.

8 pages, 6 figures; extended discussion; corrected typos; corrected figure 5 and new figure 6; conclusions unchanged