The quantum vacuum plays a central role in physics. Quantum electrodynamics(QED) predicts that the properties of the fermionic quantum vacuum can be probed by extremely large electromagnetic fields. The typical field ...The quantum vacuum plays a central role in physics. Quantum electrodynamics(QED) predicts that the properties of the fermionic quantum vacuum can be probed by extremely large electromagnetic fields. The typical field amplitudes required correspond to the onset of the ‘optical breakdown’ of this vacuum, expected at light intensities>4.7×10^(29) W/cm^(2). Approaching this ‘Schwinger limit’ would enable testing of major but still unverified predictions of power lasers. To close this considerable gap, a promising paradigm consists of reflecting these laser beams off a mirror in relativistic motion, to induce a Doppler effect that compresses the light pulse in time down to the attosecond range and converts it to shorter wavelengths, which can then be focused much more tightly than the initial laser light. However, this faces a major experimental hurdle: how to generate such relativistic mirrors? In this article, we explain how this challenge could nowadays be tackled by using so-called ‘relativistic plasma mirrors’. We argue that approaching the Schwinger limit in the coming years by applying this scheme to the latest generation of petawatt-class lasers is a challenging but realistic objective.展开更多
基金financial support from the European Research Council(ERC Grant Agreement No.694596)supported by the French National Research Agency(ANR)T-ERC program(Grant No.ANR-18-ERC2-0002)。
文摘The quantum vacuum plays a central role in physics. Quantum electrodynamics(QED) predicts that the properties of the fermionic quantum vacuum can be probed by extremely large electromagnetic fields. The typical field amplitudes required correspond to the onset of the ‘optical breakdown’ of this vacuum, expected at light intensities>4.7×10^(29) W/cm^(2). Approaching this ‘Schwinger limit’ would enable testing of major but still unverified predictions of power lasers. To close this considerable gap, a promising paradigm consists of reflecting these laser beams off a mirror in relativistic motion, to induce a Doppler effect that compresses the light pulse in time down to the attosecond range and converts it to shorter wavelengths, which can then be focused much more tightly than the initial laser light. However, this faces a major experimental hurdle: how to generate such relativistic mirrors? In this article, we explain how this challenge could nowadays be tackled by using so-called ‘relativistic plasma mirrors’. We argue that approaching the Schwinger limit in the coming years by applying this scheme to the latest generation of petawatt-class lasers is a challenging but realistic objective.
