Under the squeezed vacuum state, the quantum zero point fluctuations for both the charge and current of a non-dissipation mesoscopic coupled circuit in the presence of source are given. The quantum mechanical effects of this circuit at zero temperature are studied.
Starting from the classical motion equation of a non\|dissipative mesoscopic inductance coupled circuit with source, it investigates the fluctuations of the charge and current in the mesoscopic inductance coupled circuit at the squeezed vacuum state, and study especially the influences of the squeezed angle on the fluctuations. The results indicate if the system is in the squeezing vacuum state, the quantum fluctuations of both circuits are related reciprocally but the fluctuations are independent with the source.Also,the squeezed effect of the charge and current is depended on the squeezing parameter γ and the squeezing angle θ as well. Moreover, the fluctuation of the charge and current does not monotonously decrease in an arbitrary squeezed angle θ , instead of has a minimum. [
We study the quantum fluctuations of the charge and current of two L-C dissipative mesoscopic circuit with the mutual inductance in the vacuum state. Our results show that the system state will evolve to a squeezed coherent state under the effect of external source. We find that the squeezing amplitude parameter is relative to the parameters of circuit and the mutual-inductance coefficient in the existence of dissipation. When the circuit has no dissipation or there is complete coupling between two meshes, the squeezing amplitude parameter only depends on the capacitance's ratio.
The quantum fluctuations of the charge and current in a non-dissipative mesoscopic circuit with coupled inductors and capacitors are studied for the squeezed vacuum state. The influence of the phase angle upon the quantum fluctuations is discussed in particular. Our results indicate that when the circuit parameters remain constant and the phases θ of the two circuits are equal, the squeezing of the charge or its conjugate variable increases. When the difference of the two phases equals π, the squeezing will deteriorate. Therefore, if we want to decrease the quantum noise, we should not only control the amplitude r , but also control the phase θ carefully.