Higher-order fluctuations and squeezing of supercurrents in mesoscopic Josephson junction with light in thermal states and squeezed coherent states

The supercurrents and their even order fluctuations in the mesoscopic Josephson junction in the presence of the light in thermal states (including displaced thermal states and squeezed thermal states) and squeezed coherent states are studied. The definition of even order squeezing of the supercurrent is introduced in this Letter. The supercurrents and their fluctuations exhibit oscillations with modulated frequency for displaced thermal states, modulated amplitude for squeezed thermal states, and modulated both frequency and amplitude for squeezed coherent states. Quantization of light field leads up to the fundamental quantum fluctuations of the supercurrents. With appropriate parameters of the field, the supercurrents can be squeezed to 2nd- and higher-order. In thermal states, raising temperature will reduce the supercurrents and increase their fluctuations. Deepening the squeezing degree of the field will weaken the squeezing degree of the supercurrent.