Quantum Fluctuations

WU Hai-bo

For different states of the mesoscopic capacitive coupled electric circuit, reduction of quantum fluctuations induced by the coupling was studied. If the coupled circuit is at its ground state, or initially the system is decoupled, quantum fluctuations of the electric charge everywhere can be reduced, but that of the electric current can not. If initially the coupling part is open, quantum fluctuations of the current in the component circuits can not be squeezed; but quantum fluctuations of the current in the coupling part and quantum fluctuations of the charge everywhere can be reduced.

EDWARD B. NELSON

Michael I. Sobel

YI Shi-guang

The quantization of the generalized mesoscopic RLC parallel circuit,the quantum fluctuations of the current and the voltage of each branch in vacuum state were studied.The influences on the quantum fluctuations of the dissipative resistances in the inductance and capacitance branches were discussed.The results show that the quantum fluctuations in each branch are related to the parameters of the elements and decay with time.The quantum fluctuations in the two branches are influenced by the dissipative resistances both in the decaying factor and in the coefficients.They have the same behavior in the decaying factor but having difference in the coefficients.The quantum fluctuations of the voltage are affected by the dissipative resistances in the two branches,but the quantum fluctuations of the current are not affected by them when the values of the two dissipative resistances are same.

Wei 伟 Qi 漆, Liangwei Dong, Hai-Feng 海凤 Li 李

Abstract Considering the quantum fluctuation effects, the existence and stability of solitons in a Bose-Einstein condensate subjected in a P T -symmetric potential are discussed. Using the variational approach, we investigate how the quantum fluctuation affects the self-localization and stability of the condensate with attractive two-body interactions. The results show that the quantum fluctuation dramatically influences the shape, width, and chemical potential of the condensate. Analytical variational computation also predicts there exists a positive critical quantum fluctuation strength q c with each fixed attractive two-body interaction g 0 , if the quantum fluctuation strength q 0 is bigger than q c , there is no bright soliton solution existence. We also study the effects of the quantum fluctuations on the stability of solitons using the Vakhitov-Kolokolov (VK) stability criterion. A robust stable bright soliton will always exist when the quantum fluctuation strength q 0 belongs to the parameter regimes q c ≥ q 0 > 0.

Z. Ficek, R. Tanaś