Quantum State Control And Light Intensity Correlation

Quantum state control is an hot topic in quantum information.Its appearance has profoundly changed the way of preparing and transferring information and greatly pro-moted the development of modern information technology.Thereinto,quantum state transfer and quantum steering are two representative types.The goal of quantum state transfer is to transfer or distribute quantum state between different devices.Many dif-ferent transfer schemes has been proposed and implemented in different system such as light-atom system,optomechanical system,light-quantum dot system,superconducting system and so on.These researches laid a solid foundation for realizing future quantum networks.On the other hand,quantum steering demonstrates the nonlocal ability that by measuring the state of one part of two entangled particles,one can infer or influ-ence the state of the other part.By probing into quantum steering,we can understand quantum mechanics more clearly.Meanwhile,quantum steering has vast application in quantum information such as one-sided device-independent quantum key distribution,se-cure quantum teleportation.In actual quantum state control,an unavoidable factor is the dissipation effect from the environment.Especially,how to minimize the negative effects of environmental noise in the quantum state transfer process has become the focus of many researches.Recently,it is shown that the dissipation from engineered reservoir can also be utilized to generate quantum correlation.When interac ting with the collective mode(the Bogoliubov mode)of two other particles,a particle would exert the dissipation effect on the Bogoliubov mode just as an engineered reservoir.Due to this dissipation effect,two individual particles of the Bogoliubov mode would be correlated.In this pa-per,we investigate the quantum state control under the dissipation effect from the heat reservoir or the engineered reservoir.At first,we investigate the quantum state transfer between two mechanical oscillators in coupled cavities for the case that the cavity fields are not in the steady state.Three different schemes are presented.The first one is the double swapping scheme,i.e.,one of the two collective cavity modes interacts with one mechanical oscillator first and later with the other mechanical oscillator.The second one is to use the mechanical dark mode,which decouples from the cavity fields and evolves adiabatically from one mechanical mode to the other.The third one depends on the interactions of the two oscillators with the same continuous,collective cavity mode.In comparison,the first scheme is more robust to the mechanical thermal noise,while the second one can depress the effect of the cavity damping and the third one merges the merits of the two former schemes.Next,we study EPR steering of two entangled fields,one of which is dissipated by the atoms while the other is amplified.It is shown that the one-way steering happens from one mode to the other for different cavity decay rates and not too small cooperation parameters.An increase in the cooperation parameters leads to an increase both in the parameter region and in the degree for the one-way steering.Depending on the adiabatic and nonadiabatic conditions,the one-way steering occurs in different detuning parameter regions when the cooperation parameters are relatively small.Then we present a generalization of our system to the cases of the bright and/or collective fields.Finally,we present an optical switching of cross intensity correlation in cavity elec-tromagnetically induced transparency configuration.For the symmetrical case,the cross intensity correlation switches from negative to positive as the atom-field detunings change from negative to positive.In terms of the dressed atomic states and the Bogoliubov modes,we analyze the atom-photon interaction mechanism for the switching behavior and present a numerical verification.As a by-product,we show the existence of the intensity sum or difference squeezing in a limited region of parameters.