Entanglement in Tavis-Cummings model with Kerr nonlinearity induced by a thermal noise
The exact dynamics of a system of two identical qubits, resonantly interacting with a quantum field of an ideal microwave resonator in the presence of Kerr nonlinearity, is considered. To solve the quantum Liouville equation for the full density matrix, we used the representation of "dressed" states, that is, the eigenfunctions of the Hamiltonian. The complete set of "dressed" states of the considered model is found. On its basis, the solution of the evolution equation was found The two-qubit density matrix is used to calculate the parameter of qubit entanglement -- concurrence. The most interesting result seems to be that taking into account the initial coherence of qubits in the model with Kerr nonlinearity leads to a decrease in the maximum degree of entanglement of qubits induced by the thermal field. At the same time, in one- and multi-photon resonant two-qubit models without a nonlinear medium, the coherence of qubits leads to a significant increase in the degree of their entanglement.
Eugene K. Bashkirov
Samara National Research University
File with report