Effect of photon quantum statistics on electrons in above-threshold ionization

Strong field physics and quantum optics, two prosperous fields in modern science, have recently been connected with each other. Here, we study the quantum effect of bright squeezed vacuum light and thermal light on above-threshold ionization. With quantum strong-field approximation theory, we reveal a decoherence phenomenon caused by the statistics of photons, in which above-threshold ionization could be degenerated into a classical-like picture under the effect of quantum light. This represents a direct transition from the wavelike nature to the particlelike behavior of photoelectrons. We also reveal the ionization enhancement effect of the bunched light in photoionization from the perspective of autocorrelation function <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msup><a:mi>g</a:mi><a:mrow><a:mo>(</a:mo><a:mi>n</a:mi><a:mo>)</a:mo></a:mrow></a:msup></a:math>. The number distributions of electrons ionized by different quantum light fields are studied, and it is shown that the photon number distribution can be mapped onto the photoelectron number distribution. This finding enables the production of bunched electrons with strong-field ionization with quantum light.