小量子系统中的相干布居转移及脉冲传输特性研究
文献类型：学位论文
| 作者 | 姚海凤 |
| 学位类别 | 博士 |
| 答辩日期 | 2011 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 龚尚庆 ; 张敬涛 |
| 关键词 | 相干布居转移 前驱波 自感应透明 载波包络相位 固有偶极矩 |
| 其他题名 | Coherent population transfer and pulses propagation in small quantum systems |
| 中文摘要 | 自60年代激光问世以来，利用激光良好的相干性进行量子相干调控成为了量子光学和激光物理学等学科的前沿研究领域。在激光与原子、分子以及半导体等介质的相互作用中，产生了很多新现象，如相干布居捕获、电磁感应透明、自感应透明及光学电离等等。这些新现象不仅推动了量子光学的基础和应用研究的发展，而且促进了光物理、光化学、光生物学、量子信息科学等许多新兴或交叉学科的发展。 本学位论文主要就原子、分子以及半导体中激光脉冲的传输特性和相干布居转移进行系统研究，取得了一些创新性的研究结果，主要包括： 1. 提出了一种非对称双量子点分子中实现相干布居转移的方案。通过调节两个量子点之间的偏置电压可以控制量子点之间的电子隧穿耦合强度。在适当选择泵浦激光脉冲和隧穿耦合的条件下，可以实现系统从无激子态到间接激子态的完全转移，也可以得到无激子态与间接激子态的任意相干叠加态。 2. 研究了激光脉冲在二能级极性分子中的绝热自感应透明效应。发现由于固有偶极矩的存在，系统的跃迁频率受到与脉冲拉比频率成正比的动态修正。因此，通过调整脉冲拉比频率的峰值及脉冲宽度，能满足绝热自感应透明条件，脉冲在该介质中能无损耗无形变的透明传输，且对脉冲形状和面积均无严格要求。 3. 讨论了非线性啁啾脉冲在二能级原子介质中的传输动力学。跟一般的啁啾脉冲面积定理不同，在一定的啁啾强度和啁啾宽度条件下，入射的2π非线性啁啾脉冲在传输过程中将会分裂为光学前驱波和一个稳定的自感应透明孤子。傅里叶频谱分析表明，该非线性啁啾脉冲的频谱不仅包含中心共振的频率成分而且包含分立的高频和低频边带成分，其中共振的频率成分形成自感应透明孤子，而高频和低频边带成分则贡献于光学前驱波的形成。因此，这种脉冲分裂的现象可以推广到具有类似傅里叶频谱分布的其它形式的啁啾脉冲。另外，还讨论了啁啾参数对非线性啁啾脉冲传输演化的影响。 4. 探讨了少周期方波脉冲在子带间共振的半导体量子阱中的非线性传输。发现入射的2π方波脉冲分裂为前驱波和自感应透明孤子，且分裂产生的自感应透明孤子的脉冲宽度依赖于入射脉冲的载波包络相位。因为除了中心共振的频率成分之外还有一部分满足多光子共振条件的低频成分也对自感应透明孤子的产生有贡献，所以，孤子脉冲宽度的这种载波包络相位依赖效应源自于少周期方波脉冲频谱中高频和低频成分分布的相位依赖性。 |
| 英文摘要 | Since laser was constructed in the 1960s, the study on quantum coherent control based on its excellent coherent property has become the frontier of the cross-research area of quantum optics, laser physics and other disciplines. In the interaction of laser pulses with atoms, molecules and semiconductor, etc., many novel phenomena have been revealed, such as coherent population trapping, electromagnetic induced transparency, self-indecued transparency, photoionization, etc. These novel phenomena not only propel the development of quantum optics but also contribute to the advance of rising or cross disciplines such as optical physics, optical chemistry, optical biology, quantum information, and so on. In this thesis, we mainly investigate the quantum coherent control of population transfer and propagation properties of laser pulses in atoms, molecules and semiconductor nanostructures. The main innovative results are as follows: 1. We present a scheme for the coherent population transfer in an asymmetric quantum dot molecule by means of the interdot tunnel-coupling which can be controlled by a bias voltage. Under proper combination of the pump laser pulse and the tunnel-coupling pulse, a complete population transfer from the state without excitations to the indirect exciton state can be achieved. Additionally, by tuning the tunnel-coupling pulse, an arbitrary coherent superposition of the two states can also be prepared. 2. The adiabatic self-induced transparency in two-level polar molecules has been demonstrated. It is found that due to the presence of permanent dipole moment, the transition frequency obtains a dynamic correction which is proportional to the pulse Rabi frequency. By tuning the peak Rabi frequency of pulse and the duration of pulse, the condition for adiabatic self-induced transparency can be satisfied. Thus, pulse could propagate in a steady form without energy losses, and the phenomenon is independent of the pulse shape and its area. 3. We investigate the propagation dynamics of nonlinear chirped optical laser pulses in a two-level atom medium. It can be found that for certain chirp strength and chirp width, an incident 2π nonlinear chirped pulse will split into optical precursors and a stable self-induced transparency soliton during propagation. It results from the particular Fourier spectrum including not only central resonant frequency components but also high and low sidebands. The central resonant frequency components contribute to the formation of self-induced transparency soliton, while the high and low sidebands result in optical precursors. Thus, this phenomenon could be extended to other chirp forms which correspond to the similar Fourier spectrum. Moreover, the effects of chirp parameters on the evolution of nonlinear pulses are also discussed. 4. We study the nonlinear propagation of few-cycle rectangular laser pulses on resonant intersubband transitions in semiconductor quantum wells. An initial 2π rectangular pulse will evolve into precursors and a self-induced transparency soliton during the course of propagation. The duration of generated soliton depends on the carrier-envelope phase of the incident pulse. In our case, not only the near-resonant frequency components but also the low frequency components could contribute to the generation of the soliton pulse when the condition of muli-photon resonant is satisfied. The phase–sensitive property of the solitons results from the phase-dependent distribution of high and low frequency sidebands of few-cycle rectangular pulses. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15666]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 姚海凤. 小量子系统中的相干布居转移及脉冲传输特性研究[D]. 中国科学院上海光学精密机械研究所. 2011. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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