In a spontaneous process, laser-polarized dressings produce characteristic triphoton waveforms regarding the oscillation period and coherence time. Correspondingly, circularly polarized dressings make it have longer oscillation periods compared to the effect of linearly polarized dressings attributed to dispersion relation changes, and shorter coherence times owing to the larger dressing field. Given that the optical response of the polarization state of incident light is the dressing field, we can control the averaged three-photon coincidence count rate by adjusting the polarization of the incident light. By performing quantum tomography, we can obtain W and W-like polarization entanglement states. Accordingly, strong and weak visibilities can be evoked for circularly and linearly polarized dressings.
In a spontaneous process, laser-polarized dressings produce characteristic triphoton waveforms regarding the oscillation period and coherence time. Correspondingly, circularly polarized dressings make it have longer oscillation periods compared to the effect of linearly polarized dressings attributed to dispersion relation changes, and shorter coherence times owing to the larger dressing field. Given that the optical response of the polarization state of incident light is the dressing field, we can control the averaged three-photon coincidence count rate by adjusting the polarization of the incident light. By performing quantum tomography, we can obtain W and W-like polarization entanglement states. Accordingly, strong and weak visibilities can be evoked for circularly and linearly polarized dressings.
Abstract We research the polarized dressing control of biphotons interference and quantum tomography. Different biphotons counting rates are obtained by different polarization dressings of incident beams of lights. We calculated the counting rates of all polarized dressing schemes. The counting rate of circularly polarized dressing has been observed with shorter period of oscillation and a longer coherence time when compared with linear polarization. Since, the different polarization dressings result in different modules of third-order nonlinear susceptibilities and different linewidths. Thus, we can adjust the dressing field by changing the polarization of the incident beam of light to obtain controlled pair of photons with desired longer coherence time. Based on that, we study the impact of the two dressing fields which cause the third-order nonlinear susceptibility to be different. In the absence and presence of external dressing field, the biphoton coincidence rate is completely different. By performing quantum tomography, we get various Werner-states and the polarization states of incident lights, this also helps in comprehensive characterization of output state. Further, we define the interference visibility for different polarized dressed states. The visibility of the circularly polarized dressing field is found to be larger when compared with linearly polarized dressing field. Thus, we can obtain photons with controllable coherence time and desired visibility with different polarization schemes to uncover the indistinguishability of photon interference and promote the study of quantum optics.
Abstract The generation of a nonclassical multi-photon has aroused renewed interest in recent years. Here, we propose a new method to generate tri-photon and quad-photon correlations in time via a double-dressing spontaneous six-wave mixing and eight-wave mixing process in an atomic ensemble, respectively. When we only consider the nonlinear optical response, the coincidence counts of tri and quad photon serves as damped coherent Rabi oscillation. The coincident count of tri (quad) photon contains three (four) conditional two-photon correlation with 10 or 30 (26, 28 or 38) periods, corresponding to 11 or 19 (18 or 20) modes. These mode and periods of tri and quad photon result from destructive interference from the possible 4 or 8 six wave and 18 eight wave coherent channels, respectively. In addition, for tri-photon, the greater double-dressing field strength is, the fewer the number of periods are. The coherent times are also controlled by the double-dressing effect. Such results have potential applications in multi-mode quantum communication and quantum network.
Abstract Triphotons have a more abundant energy structure compared to biphotons. Furthermore, as the number of photons increases, excellent properties such as entangled multi-qubit states, high security, flexibility, and information capacity are observed. This leads to a growing demand for multi-body quantum information processing. Here, a method is proposed to generate a three-photon entangled state using a single six-wave mixing process in an atomic ensemble. The research examines the temporal correlation characteristics of the triphoton produced in photon coincidence counting measurements, with a focus on the linear and nonlinear susceptibilities of the six-wave mixing process. These properties primarily depend on the fifth-order nonlinear coupling coefficients responsible for the damping Rabi oscillations and the group delay determined by the longitudinal detuning function. To enhance the nonlinear interaction between the optical field and the atomic ensemble, placing the atomic ensemble in a high-quality cavity and utilizing laser cooling techniques to eliminate the internal Doppler broadening effect in the atomic gas hold promise.
Narrow-band multiphoton entanglement sources serve as a core enabling resource for advanced quantum information technologies. Recently, researchers have directly generated energy-time entangled triphoton W states in a hot atomic medium via spontaneous six-wave mixing for the first time. However, a rigorous theoretical framework for this process remains lacking to date, confining our understanding to a mere extension of the biphoton model. Here, we analytically investigate the generation mechanism of energy-time entangled triphotons and their classically controllable optical properties in an electromagnetically induced transparency-assisted five-level cold atomic system. Notably, triphoton generation follows strict temporal ordering, resulting in asymmetric quantum interference in triple coincidence counts--unreplicable and unexplainable by the inherently symmetric biphoton model. These results establish a rigorous physical framework for spontaneous six-wave mixing-generated triphotons, clarify their distinctions from states produced via cascaded nonlinear models, and substantially advance their utility in quantum information protocols.
Abstract Nonclassical multiphoton have attracted extensive attention to serve as entangled resources for quantum information technology. Here, the continuous‐mode hyper‐entangled W‐class triphotons are theoretically generated through spontaneous six‐wave mixing (SSWM) in 85Rb. In nonlinear optical response, Zeeman sub‐states are high‐dimensionally quantized by polarized dressing. High‐dimensional entanglement is structured via atomic non‐Hermitian nature. Through linear optical response, the temporal correlations are shaped via diverse polarized dressing. SSWM‐based triphoton is a genuine triphoton possessing non‐Gaussian tripartite entanglement. The high production rate is due to co‐action of three strong input fields, electromagnetically induced transparency (EIT) protection, and slow light effect. Non‐Hermitian nature endows the system with sensitive adjustability around exceptional points (EP). Eventually, the results demonstrate multiple SSWMs causing oscillations with multiple periods in three‐photon temporal correlations for the nonlinear region, build a high‐dimensional three‐body entangled quantum network and transform multifarious profiles of the three‐photon temporal correlations for the linear region. Especially, both high‐dimensional and hyper entanglements are obtained, contributing to high quantum information capacity. Further, the system is switched among multiple states when non‐Hermitian nature is manipulated by polarized dressing. The research opens a broad prospect for generating the hyper‐entangled multiphoton with potential application in adjustable quantum networks of high information capacity.
Research on entangled multipartite systems with controllable wave functions has attracted significant interest in the field of quantum optics. For quantum communications and quantum information processing, linear and nonlinear optical susceptibilities govern high-order correlations and entangled multiple-photon resources. In single- and double-dressing quadphoton correlations, we have observed the evolution of linear and nonlinear optical responses in the group delay and Rabi oscillation regimes. In the group delay regime, when linear susceptibility is evident, the quadphoton coincidence counting rate exhibits a rectangular profile. In the Rabi oscillation regime, the enhanced nonlinear susceptibility induced by strong laser dressing effects control quadphoton wave packets based on damped Rabi oscillation. Additionally, at different delay times, some photons exist in the group delay regimes, while others exist in the Rabi oscillation regimes, suggesting a coexistence mechanism. Additionally, there is a transition regime in which a portion of the photons are in both the group delay and Rabi oscillation regimes. By varying the power of the dressing field and optical depth, we realized the evolution between these two regimes for entangled quadphotons. Additionally, we demonstrate the shortening of coherence times under double-dressing conditions compared to single-dressing conditions. These results can help improving the length of coherence time and information capacity, which have great significance for the future development of long-distance and long coherent time quantum communication and quantum storage.