We study the propagation properties of a probe field in an aligned asymmetric triple quantum dot molecule with both sides inter-dot tunneling coupling effect. It is shown that the probe field can form optical soliton due to the destructive quantum interference induced by the quantum inter-dot tunneling coupling effect. Interestingly, these optical solitons can be stored and retrieved by adjusting single or double inter-dot tunneling coupling effect, different from that light memory in the ultra-cold atom system. Furthermore, we also find that the amplitude of the stored optical soliton can be adjusted by the strength of the single or double inter-dot tunneling coupling. It is possible to improve the stability and the fidelity of the optical information in the process of the storage and retrieval in semiconductor quantum dots devices.
We study the propagation properties of a probe field in an aligned asymmetric triple quantum dot molecule with both sides inter-dot tunneling coupling effect. It is shown that the probe field can form optical soliton due to the destructive quantum interference induced by the quantum inter-dot tunneling coupling effect. Interestingly, these optical solitons can be stored and retrieved by adjusting single or double inter-dot tunneling coupling effect, different from that light memory in the ultra-cold atom system. Furthermore, we also find that the amplitude of the stored optical soliton can be adjusted by the strength of the single or double inter-dot tunneling coupling. It is possible to improve the stability and the fidelity of the optical information in the process of the storage and retrieval in semiconductor quantum dots devices.
Soliton, which can travel over long distance without attenuation or shape change due to the balance of the interplay between dispersion (or diffraction) and nonlinearity in nonlinear medium, becomes a good information carrier in quantum information processing and transmission. Up to now, the study on the optical solitons mainly focuses on ultra-cold atomic electromagnetic induction transparency (EIT) medium. This is mainly because ultra-cold atomic system can generate strong nonlinear effect under low light excitation. However, for the practical application, it is a big challenge to control accurately the optical soliton dynamics in the atomic EIT medium due to its low temperature (which approaches to absolute zero) and rarefaction. Fortunately, with the maturity of semiconductor quantum production technology, quantum dots have extensive application prospect in quantum information processing and transmission. So, in the paper, we study the optical soliton dynamics in a four-level asymmetric array-type three-quantum-dot EIT medium. Based on the current experimental results, we first propose a four-level asymmetric array-type three-quantum-dot EIT model. Subsequently, by using amplitude variable approach combined with multi-scale method, we study analytically the propagation of a probe pulse in this system. It is shown that when one (the another) inter-dot tunneling coupling is turned on (off), only a single transparency window appears in the center range of the probe field detuning. Only if two inter-dot tunneling couplings are turned on will two transparent windows be distributed on both sides of the central region of the probe field detuning. And the width of the single transparent window or the widths of two transparent windows become wider with the strength of the inter-dot tunneling coupling increasing. For the nonlinear case, by choosing appropriate parameters in the area of the transparency window, the stable propagation of soliton can be realized. Interestingly, we find that the strength of the inter-dot tunneling coupling has an important effect on the soliton dynamic behaviors. In the case that one (the another) inter-dot tunneling coupling is turned on (off), with the increase of strength of the inter-dot tunneling coupling, the velocity of the soliton exhibits a trend of first increasing and then decreasing, and the amplitude of the soliton presents a increasing trend for ever. For the case that two inter-dot tunneling couplings are turned on, with the strength of the two inter-dot tunneling coupling increasing, the velocity of the soliton presents a decreasing trend for ever, while the amplitude of the soliton exhibits a trend of first decreasing and then increasing. Thus, the amplitude modulation effect of optical soliton can be realized in semiconductor quantum dot devices.
The best carrier for quantum information transmission is light signal, which has a fast propagation speed and can carry a large amount of information. However, during the propagation of light, dispersion effect and diffraction effect can cause quantum information to be distorted to a certain extent. On the contrary, optical solitons are formed due to the balance between the system’s dispersion (diffraction) effect and nonlinear effect, and they exhibit very high stability and fidelity. Therefore, they have received widespread attention in electromagnetically induced transparency (EIT) media with ultracold atoms. However, cold atomic gas media require extremely low operating temperatures, and the performances of the materials are difficult to control precisely. These factors are unfavorable for the miniaturization and integration of future information devices, thus significantly limiting their practical applications. Semiconductor quantum dot media, on the other hand, possess advantages such as discrete energy level structures and spectral properties similar to those of cold atomic gases, longer decoherence times, larger electric dipole moments, more significant nonlinear optical effects, and easy integration, making them an ideal alternative to cold atomic media. In this work, semiconductor quantum dots are coupled with optical fibers, the most common carrier in optical communication, to explore the formation, storage, and retrieval of temporal optical solitons in the coupled system. The results show that due to the tunneling-induced transparency effect between dots in semiconductor quantum dot molecules, light absorption in the system is greatly suppressed. At the same time, the transverse confinement of the nanofiber can enhance the interaction between light and the system, and the enhanced nonlinear response of the system can balance the dispersion effect, resulting in stable temporal optical solitons. Further research indicates that by turning on and off the inter-dot tunneling coupling, the high-efficiency and high-fidelity storage and retrieval of optical solitons can be realized in the system. These findings have certain guiding significance and potential application value for the processing all-optical information in solid quantum materials.
The tunneling-induced optical properties in weak probe pulse propagation are investigated through a quadruple quantum dot (QQD) molecule composed of a center dot and three satellite dots. The dynamic control of pulse propagation is addressed by solving the Maxwell–Bloch equations for the QQD medium and field simultaneously in space and time. It is found that by properly adjusting the system parameters, an absorptive case for the probe pulse can be switched to a case in which the light pulse propagates without significant absorption for quite a long propagation distance. An analytical solution is presented to comprehend such a controllable switch. Finally, it is shown that it is possible to store and retrieve the probe pulse in such a QQD system through adiabatically varying the tunneling couplings. The proposed scheme may provide a guideline to develop a new type of optical storage device.
We consider the coupling effect between interdot tunneling coupling and external optical control field to study the linear optical property and the formation of temporal optical solitons in a quantum dot molecules system, analytically. The results show that the double tunneling induced transparency (TIT) windows are appeared in the absorption curve of probe field because of the formation of dynamic Stark splitting and quantum destructive interference effect from the two upper levels. Interestingly, the width of the TIT window becomes wider with the increasing intensity of the optical control field. We also find that the Kerr nonlinear effect of the probe field can be modulated effectively through coherent control both the control field and the interdot tunneling coupling in this system. Meanwhile, we demonstrate that the formation of dark or bright solitons can be practical regulated by varying the intensity of the optical control field.
We investigated the steady optical properties of the triple quantum dots, which obtain a tunneling-induced effect by using the external electric field. Our numerical results shown that the electromagnetically induced transparency can be achieved via the tunneling-induced effect. In addition, we examined the propagation dynamics of a probe field in this system and found that the probe field group velocities and their absorption were related to the tunneling coupling intensities. This finding allowed us to control the probe field to obtain ultraslow group velocities and a tunable optical switch. Finally, using this scheme it was possible to store and release the probe field by modulating the tunneling coupling sequences.
We investigate the dynamic propagation of a probe field via the tunneling-induced interference effect in a triple model of quantum dot molecules. By theoretical analysis and numerical simulation, we find that the number of transparency window relate to the energy splitting and the group velocity of probe field can be effectively controlled by the tunneling coupling intensity. In addition, in the process of light storage and retrieval, when the excited states have no energy splitting in the storage stage but opposite values of the energy splitting in the retrieval stage, the beating signals can be generated.