Using High-Power Lasers for Detection of Elastic Photon-Photon Scattering

Abstract

The properties of four-wave interaction via the nonlinear quantum vacuum is investigated. The effect of the quantum vacuum is to generate photons with new frequencies and wave vectors, due to elastic photon-photon scattering. An expression for the number of generated photons is derived and using state-of-the-art laser data it is found that the number of photons can reach detectable levels. In particular, the prospect of using the high repetition Astra Gemini system at the Rutherford Appleton Laboratory is discussed. The problem of noise sources is reviewed, and it is found that the noise level can be reduced well below the signal level. Thus, detection of elastic photon-photon scattering may for the first time be achieved. PACS numbers: 12.20.Fv, 42.50.Xa Classically, elastic photon-photon scattering does not take place in vacuum. However, according to quantum electrodynamics (QED), such a process may occur owing to the interaction with virtual electron-positron pairs. Several suggestions to detect photon-photon scattering have been made, for example using harmonic generation in an inhomogeneous magnetic field [1], using resonant interaction between eigenmodes in microwave cavities [2,3], using ultra-intense fields occurring in plasma channels [4], as well as many others, see e.g. Refs. [5,6,7]. Related to, but physically different from, elastic photon-photon scattering is photon splitting [8] (see also [9]) and Delbrück scattering [10], the latter being detectable using high-Z atomic targets [10]. However, no suggestions have yet led to detection of elastic scattering among real photons.In the present Letter we will investigate the possibility to detect photon-photon scattering in vacuum using four-wave mixing, where three colliding laser pulses stimulate emission in a fourth direction with a new frequency. Four-wave mixing has the advantage of not being limited by the low cross section for photon-photon scattering [11]. A similar scheme was first studied by Ref. [12], and further theoretical [13,14,15] and experimental [16] studies of QED four-wave mixing have been performed since then. However, so far the available laser technology has not been sufficiently powerful to allow for successful detection of scattering events. Moreover, even with high laser power, the laser setup and geometry in such an experiment is important. In particular, we argue that a two-dimensional (2D) setup preferred in earlier literature is unlikely to produce a detectable signal. This is in contrast to the 3D setup presented in this Letter. We have calculated the coupling coefficient for four-wave mixing as a function of incident angles and laser polarization. For given data of the laser beams, together with the coupling coefficients, the number of scattered photons can be calculated. The analysis is then used * Currently at: Department of Physics, Stockholm University, SE-106 91, Sweden to suggest a novel concrete experiment, where the parameters are chosen to fit the Astra Gemini (AG) system (operational 2007) located at the Centr...

Extremely high-intensity laser interactions with fundamental quantum systems

“…In this laser-assisted setup the "signal" of photon-photon scattering is, of course, the remaining outgoing photon. In Lundin et al, 2007 andLundström et al, 2006 an experiment has been suggested to observe laser-assisted photon-photon scattering with the Astra-Gemini laser system (see Sec. II.A).…”

An addendum to the Heisenberg-Euler effective action beyond one loop

“…Recently, indications have been reported for the relevance of QED vacuum birefringence for optical polarimetry of a neutron star [36]. Other theoretical proposals for optical signatures of quantum vacuum nonlinearity have focused on photon-photon scattering in the form of laser-pulse collisions [37][38][39][40], interference effects [41][42][43][44], quantum reflection [45,46], photon merging [47][48][49][50][51], photon splitting [19,[52][53][54][55][56][57][58][59][60], and higher-harmonic generation from laser driven vacuum [61][62][63][64]. Finally, and perhaps most strikingly, strong electric fields can facilitate the spontaneous formation of real electron-position pairs from the QED vacuum via the Schwinger effect [2,14,15].…”

Quantum-electrodynamical parametric instability in the incoherent photon gas

“…Similar to the classic four-wave mixing process, the quantum vacuum effect can generate photons with new frequencies by four-wave interaction due to elastic photonphoton scattering [2]. Recently the matterless double slit was suggested to observe the photon-photon scattering and to realize the controlling of light with light [3,4].…”