Quantum electrodynamics experiments with colliding petawatt laser pulses

A new generation of high power laser facilities will provide laser pulses with extremely high powers of 10 petawatt (PW) and even 100 PW, capable of reaching intensities of 10(23) W/cm(2) in the laser focus. These ultra-high intensities are nevertheless lower than the Schwinger intensity I-S = 2.3 x 10(29) W/cm(2) at which the theory of quantum electrodynamics (QED) predicts that a large part of the energy of the laser photons will be transformed to hard Gamma-ray photons and even to matter, via electron-positron pair production. To enable the investigation of this physics at the intensities achievable with the next generation of high power laser facilities, an approach involving the interaction of two colliding PW laser pulses is being adopted. Theoretical simulations predict strong QED effects with colliding laser pulses of >= 10 PW focused to intensities >= 10(22) W/cm(2).