Robust Generation Of Entangled State Via Ground-state Antiblockade Of Rydberg Atoms

Quantum information science is a product of quantum mechanics and information science,which is built depending on the entanglement of quantum states and the features of quantum mechanics.No matter how far apart two subsystems in entangled state are,the relation between them still exists.As the core of the development of quantum information,the study of quantum entanglement could realize the encoding,storage,extraction and transmission of the information via the operations on entangled states.Here we proposed a scheme to generate the entangled states via the ground state antiblockade of a three-level Rydberg atom and realize the generation of the maximally entangled state of two atoms with three kinds of pulse by the use of the present experimental technology.An atom in an excited state?high energy level?is unstable.Without the effect of external conditions,the electron will still spontaneous from the excited state to the lower energy state.Atomic spontaneous emission reduce the fidelity of entangled states.The introducing of the A-type three-level Rydberg atom could effectively inhibit the spontaneous radiation of high energy levels.Thus,the quantum information could be encoded on two ground states of ?-type three-level atoms.Between Rydberg atoms there are long distance dipole-dipole interaction and Van der Waals interaction.The large dipole moment of Rydberg atoms increasing the intensity of RRI?Rydberg-Rydberg interaction?which resulting the dipole blocking effect between Rydberg atoms.The blockade effect could prevent multiple atoms get to a Rydberg state at the same time.So the evolution of one atom could be determined by the state of another one.Strong dipole interactions between atoms propagated by pulse laser fields to excited states?Rydberg states?have been proposed and reported by with the properties.This strong dipole interactions form a mechanism to deal with the entanglement operations for neutral atomic states.Other scholars proposed to generate the entangled states via the ground state blocking effect.By encoding the quantum information on the ground states?the initial state is|??=?|gg>-|ee>?/2^1/2),the spontaneous emission of the Rydberg state could be effectively inhibited.Based on previous schemes,we realize the purpose of generating the entangled states with the ground states antiblocking effect of Rydberg atom and obtain the maximally entangled state by three pulse ways.Firstly,We first utilize the form of sin2?cos2?functions to prepare the maximally entangled state which needs the exactlly interaction time to obtain the target state.Secondly We choose parameters for the laser pulses suitably to fulfill the boundary condition of the STIRAP?Stimulated Raman adiabatic passage?,which does not restricted to an accurate interaction time but requires a relatively long time..Finally,In order to obtain the state|?)with STAP?Shortcuts to adiabatic passage?,Compared with the former two methods,this STAP-based entanglement generation requires neither a long time nor an acurate interaction time.The strictly numerical simulation reveals that the current scheme is robust against spontaneous emission of atoms due to the virtual excitation of Rydberg states,and all of the above methods favor a high fidelity with the present experimental technology.