Quantum Correlation And Dissipative Dynamics Of Magnetic-resonance Force Microscopy

In this paper we derive the Lindblad and Redfield forms with and without secular approximation from the Born-Markov master equation for open quantum systems.The spectral correlation tensor of bath(the Fourier transform of the bath correlation function)and then the coefficients in the two forms of the master equation are reevaluated according to the scheme in Ref.[Phys.Rev.A99,022118(2019)] They are complex numbers rather than the real numbers getting from traditional simplified methods.The dynamics of two models(one is an open three-level quantum system model,and the other is the model of phycoerythrin 545(PE545)of modeling a photosynthesis reaction center)are studied by using the obtained equations.The non-secular Lindblad and Redfield equations with the complex coefficients predict almost the same dynamical results from the Born-Markov master equation.However,the results obtained from the traditional Lindblad and Redfield equations deviate the actual dynamics of the open quantum systems.Then,we study the dynamics of a time-dependent quantum dissipative system,the magnetic resonance force microscope(MRFM).We analyze the relationship between the amplitude of a cantilever and the state of spins in the magnetic resonance force microscopy(MRFM).It has been shown that the polarization of a single spin can be read out from the amplitude of the oscillating cantilever through moving cantilever on spins of a small ensemble.Based on the idea we propose a scheme for detecting the entanglement evolution of two coupling spins in this small ensemble.The relationship between the oscillating amplitude of the cantilever and the entanglement of the two coupling spins is carefully analyzed.This scheme may make the measurement of entanglement become more convenient.