All-optical Quantum Simulation Of Ultrastrong Optomechanics

The realization of single-photon ultrastrong-coupling regime in cavity optomechanics is a particularly significant task in this field,because various interesting and important few-photon optomechanical effects have been found in this regime,including photon blockade effect,phonon sideband spectrum,and macroscopic quantum superposition.These physical phenomena are based on the radiation pressure interaction between electromagnetic fields and mechanical vibrations.However,the current single-photon optomechanical coupling achieved in experiments is too weak to observe the few-photon optomechanical effects.Therefore,how to enhance the optomechancial coupling strength is still a desired task in this field.Inspired by one of the most important motivations for quantum simulation is to simulate the experimentally inaccessible physical effects based on the experimentally accessible systems.In this thesis,we present an all-optical scheme to simulate ultrastrong optomechanical coupling based on a Fredkin-type interaction,which consists of two exchange-coupled modes with the coupling strength depending on the photon number in another controller mode.By utilizing a strong driving to pump one of the two exchanging modes and using the physical idea of Bogoliubov approximation,we can obtain the coupling enhancement assisted by the displacement amplitude.Our numerical simulations demonstrate that the enhanced optomechanical coupling can enter the single-photon strongcoupling and even ultrastrong-coupling regimes.We also show the creation of macroscopic quantum superposed states,the implementation of a weak-tostrong transition for quantum measurement,and the observation of photon blockade effect in this system.Our work will pave the way to quantum simulation of single-photon optomechanical effects with current experimental platforms.This thesis consists of five chapters:In the first chapter,we introduce the research background and significance of cavity ulstrastrong optomechanics,and then briefly introduce several methods for enhancing the optomechanical coupling strength.In the second chapter,we introduce the basic knowledge of cavity optomechanics,quantum simulation,the Schr(?)dinger cat states,quantum weak measurement,and photon blockade effect.In the third chapter,we derive the generalized optomechanical interaction Hamiltonian(approximate Hamiltonian)based on the Frendkin-type interaction,and analyze the validity of the approximate Hamiltonian by calculating the fidelity in both closed-and open-system cases.Finally,by showing the the three important ratios in cavity optomechanics,we see that the enhanced optomechanical coupling strength can be more clearly observed.In the fourth chapter,based on the enhanced optomechanical interaction strength,we show the generation of the Schr(?)dinger cat states in the mechanical-like mode.By tuning the coupling strength from weak to strong,we can realize the quantum measurement transition from weak-value limit to the expectation-value limit.In addition,we can observe the photon blockade effect by pumping an extra weak driving on the system.Finally,we give some discussions on the experimental implementation of this scheme.In the fifth chapter,we summarize this thesis and look forward to the future work in this field.