22,980 research outputs found
Time evolution of Wigner function in laser process derived by entangled state representation
Evaluating the Wigner function of quantum states in the entangled state
representation is introduced, based on which we present a new approach for
deriving time evolution formula of Wigner function in laser process.
Application of this fomula to calculating time evolution of photon number is
also presented, as an example, the case when the initial state is photon-added
coherent state is discussed.Comment: 6 pages, revtex
The triangle-free graphs with rank 6
The rank of a graph G is defined to be the rank of its adjacency matrix A(G).
In this paper we characterize all connected triangle-free graphs with rank 6
Nonclassicality of photon-added squeezed vacuum and its decoherence in thermal environment
We study the nonclassicality of photon-added squeezed vacuum (PASV) and its
decoherence in thermal environment in terms of the sub-Poissonian statistics
and the negativity of Wigner function (WF). By converting the PASV to a
squeezed Hermite polynomial excitation state, we derive a compact expression
for the normalization factor of m-PASV, which is an m-order Legendre polynomial
of squeezing parameter r. We also derive the explicit expression of WF of
m-PASV and find the negative region of WF in phase space. We show that there is
an upper bound value of r for this state to exhibit sub-Poissonian statistics
increasing as m increases. Then we derive the explicit analytical expression of
time evolution of WF of m-PASV in the thermal channel and discuss the loss of
nonclassicality using the negativity of WF. The threshold value of decay time
is presented for the single PASV.Comment: 14 pages and 7 figure
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