Photon/Phonon Correlation In Cavity QED System And Its Application

The investigation of photon/phonon correlation in cavity quantum electrodynamics(QED)system is one of the main topics of modern science.The characterization of the quantum properties of the field through quantum correlation has very important applications in quantum precision measurement and quantum information.In the 1960 s,Glauber proposed the quantum theory of optical coherence,and successfully explained the bunching phenomenon observed in the experiments of Hanbury-Brown and Twist by the properties of light field described by photon correlation function.Glauber's theory not only describes the nature of light,but also establishes the theoretical basis of quantum optics.Glauber's first-and second-order correlation functions characterize the classical properties(e.g.,the intensity of the field)and quantum statistical properties(e.g.,bunching and antibunching behaviors)of field,respectively.By using these correlation functions,we can further study the properties of quantum field and explore novel physical phenomena in various systems.For example,single-photon/phonon blockade effect can be described by observing the second-order photon/phonon correlation function,where there is a very strong antibunching behavior between photons/phonons.The correlation functions can even be a spectroscopic technique used in high-precision measurements.The response of the photons/phonons statistics spectrum to the system parameters can be used in the measurement of weak values(e.g.,weak coupling and weak mass).In addition,the quantum statistics spectrum can also be used as a witness for quantum coherence of system.This broadens the realm of optical spectroscopy,and has potential applications in precision measurement and quantum coherence of biochemical processes.Here,we investigate the photon/phonon correlation in cavity QED system and its application in describing some special physical phenomena and weak value measurements.The thesis mainly consists of four parts:1.We apply a spectroscopic technique—photon statistics spectrum—to detect the weak light-matter interaction strength in a cavity QED system.We find that the photon statistics spectrum has a strong sensitivity on the light-matter coupling strength compared with the traditional excitation spectrum.Specially,the photon statistic spectrum occurs obvious shifts,when the cavity QED system is driven by the strong correlated photons from the halfway between the central peak and each side peak of the excitation spectrum of the source system.We show that the weak light-matter interaction strength can be measured with high accuracy even when the strong system dissipation is included.2.We study multi-photon blockade effect in a cavity QED system under the weak coupling regime by using usual photon correlation.By observing the statistical properties of the system photons described by the second-order and third-order photon correlation functions,we find that the two-photon blockade with two-photon bunching and three-photon antibunching can be obtained even when the strong system dissipation is included.Moreover,the unconventional photon blockade effect with suppression of two-photon correlation and enhancement of three-photon correlation can be realized in our proposal.3.We present a method for implementing multi-phonon bundle emission with high purity based on the electron-phonon coupling in an acoustic cavity QED system.The mechanism relies on Stokes resonances that generate super-Rabi oscillations between states with a large difference in their number of excitation,which,combined with dissipation,transform coherently pure n-phonon states into strongly correlated phonons outside of the cavity.This process is tunable optically with well-resolved operation conditions,and is robust to varying electron-phonon coupling strengths and/or driving strengths.We find close to 99% two-phonon and 97% three-phonon emission with today's figures of merit.Moreover,by extending the standard correlation function to the bundle correlation function,we demonstrate that the antibunched,uncorrelated,or bunched bundles emission can be obtained from our devise.This broadens the realm of quantum phononics,with potential applications for on-chip quantum information processing,quantum metrology,and engineering of new types of quantum devices,such as optically heralded n-phonon lasers and guns.4.We extend the collective radiance theory to the ultrastrong coupling regime and investigate the collective radiance characteristics of qubits.We rewrite the radiance witness in terms of the resonator-qubit dressed basis,which is valid for any resonator-qubit coupling strength.We find that ultrastrong resonator-qubit coupling could significantly enhance the collective radiance of qubits under the condition of resonantly driving the dressed state of the system,which leads to the emergence of enhanced hyperradiance.Interestingly,we show that the parity-symmetry-breakinginduced cascade transition can also significantly enhance the collective radiance of the qubits,which allows us to manipulate the transitions between subradiance,superradiance,hyperradiance via adjusting the parity symmetry of the system with an external magnetic field.This work is fundamentally interesting in building the collective radiance theory in the ultrastrong coupling regime,and offers potential applications in the engineering of laser devices.