Shedding light on electron–laser interactions
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One scenario Yuan Shi explored was what happens when a charged particle oscillates between two regions of constant acceleration.
When an electron encounters a laser pulse, it “wiggles” and radiates electromagnetic waves. As simple as this may sound, scientists have long struggled with an unresolved question: is the radiation energy provided by the laser or the electron? At low laser intensity, it has been experimentally confirmed that the radiation energy is entirely provided by the laser, while at higher laser intensity, it is expected that the electron will start to contribute. However, when and how the electron will contribute is still a matter of debate because the relevant laser intensity is too high to study experimentally.
Rather than waiting for the next generation of lasers, Yuan Shi (PHYS) has studied the essential physics through a complementary setup, in which the electron oscillates in an electrostatic trap rather than in a laser. Watching the trapped electron for a very long time is equivalent to making the electron wiggle with a very intense laser. Through these experiments, Shi identified experimental signatures that will indicate the electron is contributing to radiation: whether the electron contributes or not is indicated by whether the boundary between classical and quantum physics has been crossed.
This research was supported by the Laboratory Directed Research and Development Program (19-ERD-038).
[Y. Shi, Radiation reaction of classical hyperbolic oscillator: Experimental signatures, Annals of Physics 405, 130–154 (2019), doi: 10.1016/j.aop.2019.03.010.]
