Abstract The competition and coexistence between linear and nonlinear multiphoton optical responses in multidressing fields; these exhibit shaping temporal waveforms is investigated. In the group delay regime, the width of the rectangular profile in double‐dressing fields is reduced compared to that of the single‐dressing field. In the Rabi oscillation regime, the number of periods in double‐dressing fields increases relative to the single‐dressing field, and the tri‐ and quadphotons are observed to feature six and nine coherent channels, respectively. Finally, changing the optical depth and power of the dressing field can alter the optical response. Compared with the single‐dressing field, cascaded and nested double‐dressing fields reduce the linear coherence time and increase the number of periods; this is useful for photon storage and long‐distance communication. Moreover, increasing the number of dressing coherent channels increases the high‐dimensional entangled information capacity, which is more conducive to the realization of quantum communication and quantum networks.
Abstract The competition and coexistence between linear and nonlinear multiphoton optical responses in multidressing fields; these exhibit shaping temporal waveforms is investigated. In the group delay regime, the width of the rectangular profile in double‐dressing fields is reduced compared to that of the single‐dressing field. In the Rabi oscillation regime, the number of periods in double‐dressing fields increases relative to the single‐dressing field, and the tri‐ and quadphotons are observed to feature six and nine coherent channels, respectively. Finally, changing the optical depth and power of the dressing field can alter the optical response. Compared with the single‐dressing field, cascaded and nested double‐dressing fields reduce the linear coherence time and increase the number of periods; this is useful for photon storage and long‐distance communication. Moreover, increasing the number of dressing coherent channels increases the high‐dimensional entangled information capacity, which is more conducive to the realization of quantum communication and quantum networks.
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.
Abstract Here, a method to generate and shape the tri‐photon entanglement in the temporal domain via simplified single step of six‐wave mixing processes of hot atomic gas media is proposed. The effect of dressing fields on shaping the tri‐photon temporal waveform is discussed. Cascade double dressing fields will reduce the width of rectangular profile of tri‐photon waveform when compared to the single dressing field. Conversely, nested double dressing fields will widen the width of rectangular profile of tri‐photon waveform. The double dressing field will affect the coherence time of linear optical response. The relationship between phase matching bandwidth and electromagnetically induced transparency bandwidth will decide the shape of temporal waveform and coherence time in linear optical response. The transition of nonlinear optical response to linear optical response can be completed by regulating the dressing fields. The results of this proposed study have potential impact on long‐distance quantum communication, high‐dimensional entanglement, and photon storage.
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 The nonclassical states of light serve as potential candidates for emerging quantum information processes. A quantum information unit with higher information capacity is interesting and useful in large quantum information systems, such as quantum computations. The most mature way to increase information capacity is to employ a post‐selection or cascaded method with the biphoton state and polarizing beam splitters to increase the qubits of the entangled state. Another promising processing is shaping the temporal correlations of entangled state to high‐dimensional entangled states to increase the superposed states of each qubit. Based on the photon pair state in a hot atomic ensemble, experiments are conducted to shape its temporal correlations to multi‐periodic Rabi oscillations and nonlinear phase shifts. By employing the external dressing field to quantum transitions, the nonlinear interaction produces multiple frequency modes, shaping the temporal correlation of photon pairs to multi‐periodic Rabi oscillation and proposing a 3D energy–time‐entangled qubit for photon pair state. Interestingly, the maximum peak of the periodic Rabi oscillation can migrate with a longer correlation time because of a nonlinear phase shift. Wave shaping of the photon pair state, therefore, has the potential for applications in quantum information processes with higher information capacity and quantum memory.
The fifth-order nonlinear polarizability has been extensively studied in the field of quantum communication due to its ease of manipulation. By adjusting the relative size of the Rabi frequency and dephasing rate of the dressing field, natural non-Hermitian exceptional points can be generated, and further evolution can be achieved by varying the types of dressing fields. However, as the demand for information capacity in quantum communication continues to increase, research on the higher-order seventh-order nonlinear polarizability, based on four-photon states, and the number of coherent channels and resonance positions has gradually come to the forefront. This paper focuses on the simultaneous generation of a seventh-order nonlinear polarizability through a spontaneous eight-wave mixing (SEWM) process in an atomic medium involving four photons. Compared to the fifth-order nonlinear polarizability, the seventh-order polarizability shows an exponential increase in coherent channels and resonance positions due to its strong dressing effect. Additionally, the interaction between the four photons is stronger than that between three photons, making it possible for even the difficult-to-dress eigenvalues to be influenced by the dressing field and dephasing rate, resulting in more complex coherent channels. These are manifested as more complex, damped Rabi oscillations, with periods that can be controlled by the dressing field. These findings may contribute to a promising new method for quantum communication.
The biphoton states have served as one of the candidates for most quantum‐enabled technologies. Moreover, with the benefit of photon–atom interactions, biphotons with controllable wave functions are particularly interesting in quantum information processes. Herein, an experimental realization of the shaping temporal correlation of biphotons from the four‐wave mixing process in a hot Rb atomic ensemble is presented. Based on the slow‐light effect and electromagnetically induced transparency in the group delay region, the precursor‐like propagation is observed and separated from the rising edge of the delayed wave packets of biphotons temporal correlation. In addition, the application of an additional dressing field enriches the features of the biphotons temporal correlation such as the manipulation of the dispersion experienced by the generated photons and controllable coherent time. Furthermore, with a higher optical depth and stronger dressing coupling effect, the temporal correlation of biphotons is shaped from the group delay region to the Rabi oscillation region and even superposed of them.