  According to the statistical distribution laws, all the elementary particles
in the real 3+1-dimensional world must and only be chosen as either bosons or
fermions, without exception and not both. Here, we experimentally verified that
a quantized current-biased Josephson junction (CBJJ), as an artificial
macroscopic "particle", can be served as either boson or fermion, depending on
its biased dc-current. By using the high vacuum two-angle electron beam
evaporations, we fabricated the CBJJ devices and calibrated their physical
parameters by applying low-frequency signal drivings. The microwave
transmission characteristics of the fabricated CBJJ devices are analyzed by
using the input-output theory and measured at 50mK temperature environment
under low power limit. The experimental results verify the theoretical
predictions, i.e., when the bias current is significantly lower than the
critical one of the junction, the device works in a well linear regime and thus
works as a harmonic oscillator, i.e., a "boson"; while if the biased current is
sufficiently large (especially approaches to its critical current), the device
works manifestly in the nonlinear regime and thus can be served as a two-level
artificial atom, i.e., a "fermion". Therefore, by adjusting the biased
dc-current, the CBJJ device can be effectively switched from the boson-type
macroscopic particle to the fermion-type one, and thus may open the new
approach of the superconducting quantum device application.
