Small Impacts

Paul Busch

Clemens Watzenböck, Markus Wallerberger, Laurenz Ruzicka +3 more

We study photoexcitations in small Hubbard clusters of up to 12 sites. After the electric field pulse some of these clusters show an increase of the double occupation through impact ionization. We treat the time-dependent electromagnetic field classically and calculate time evolution by exact diagonalization. As a tool for better analyzing the out-of-equilibrium dynamics, we generalize the Loschmidt amplitude. In this way we are able to resolve which many-body energy eigenstates are responsible for impact ionization and which ones show pronounced changes in the double occupation and spin energy. Our analysis reveals that the increase of spin energy is of little importance for impact ionization. We further demonstrate that, for one-dimensional chains, the optical conductivity has a characteristic peak structure originating solely from vertex corrections.

Taras Plakhotnik

Long Xiao-xia

Taking semiconductor GaAs optical micro-cavity for example,the impact of the optical micro-cavity on the temperature and heat capacity of Bose condensation in exciton-photon system are researched in this paper.It shows that critical temperature of Bose condensation increases with rising of micro-cavity's width,but it is significant only when the width of micro-cavity is small.There's not Bose condensation in the system when the width of micro-cavity is very small.The variety of Bose condensation's critical temperature is little with the position in micro-cavity.The critical temperature is high in the vicinity of in micro-cavity.Photon and exciton contribute on heat capacity nearly the same.They are both increasing with temperature,and decreasing with the width of micro-cavity.The impact of micro-cavity shape on the temperature and heat capacity of Bose condensation is little.The change of heat capacity with position is obvious only when the width of micro-cavity is very small.

Yan Chen, Yong Shen, Guang‐Zhao Tang +1 more

We calculate the magnitude of cross phase modulation (XPM) induced by classical channels, and analyze its impact on quantum secure key rate. The results show that the XPM induced by classical signals is small and its impact on the quantum key distribution can be neglected.

Siyi Wang, Anupam Chattopadhyay