A coherent mechanism of robust population inversion in atomic and molecular systems by a chirped field is presented. It is demonstrated that a field of sufficiently high chirp rate imposes a certain relative phase between a ground and excited state wavefunction of a two-level system. The value of the relative phase angle is thus restricted to be negative and close to 0 or $-π$ for positive and negative chirp, respectively. This explains the unidirectionality of the population transfer from the ground to the excited state. In a molecular system composed of a ground and excited potential energy surface the symmetry between the action of a pulse with a large positive and negative chirp is broken. The same framwork of the coherent mechanism can explain the symmetry breaking and the population inversion due to a positive chirped field.
In this work, we exploit the idea of composite pulses to achieve robust population inversion in a three-level quantum system. The scheme is based on the modulation of the coupling strength, while the other physical parameters remain unchanged. The composite pulses sequence is designed by vanishing high-order error terms, and can compensate the systematic errors to any desired order. In particular, this scheme keeps a good performance under the disturbance of waveform deformations. This trait ensures that population inversion can be nearly obtained even when the pulse sequence has a short jump …
Polaron master equation theory of pulse driven phonon-assisted population inversion and single photon emission from quantum dot excitons
我们引入一个直观的半解析极化子主方程方法来模拟脉冲驱动的粒子数反转和从量子点激子发射的单光子。主方程理论允许一个确定重要的声子诱导散射率解析，并充分包括随时间变化的泵场的作用。作为该理论的应用，我们首先研究了由时变激光脉冲驱动的量子点的共振态和非共振态，发现声子发射引起的粒子数反转与Quilter { \em et al.}最近的实验直接一致，Phys Rev Lett { \bf 114}，137401（2015）。然后，我们在弱耦合腔中模拟量子点，并显示激子驱动和腔驱动系统之间的人口响应的差异。最后，我们评估的非共振声子辅助加载计划与一个量子点共振耦合到一个腔作为一个确定性的单光子源，并比较和对比的重要数字的优点与直接拉比振荡的人口使用共振$π$脉冲，后者被证明是更有效的。
We find that a suppression of the collapse and revival of population inversion occurs in response to insertion of Gaussian quenched disorder in atom-cavity interaction strength in the Jaynes-Cummings model. The character of suppression can be significantly different in the presence of non-Gaussian disorder, which we uncover by studying the cases when the disorder is uniform, discrete, and Cauchy-Lorentz. Interestingly, the quenched averaged atom-photon entanglement keeps displaying nontrivial oscillations even after the population inversion has been suppressed. Subsequently, we show that disor…
We present a blueprint for a maser with a single three-level transmon superconducting artificial atom. The system can be pumped coherently via a two-photon process, and to achieve high population inversion, the relaxation rate of the metastable state is increased via an auxiliary low-Q cavity coupled to a transition between the transmon excited states. We show numerically that such a maser can operate both in the intermediate coupling regime with super-Poissonian photon statistics and in the strong coupling regime, where the statistics is sub-Poissonian. For the former, the maser exhibits thre…
Starting from a quantum description of multiple Lambda-type 3-level atoms driven with a coherent microwave field and incoherent optical pumping, we derive a microscopic model of lasing from which we move towards a consistent macroscopic picture. Our analysis applies across the range of system sizes from nanolasers to the thermodynamic limit of conventional lasing. We explore the necessary conditions to achieve lasing without inversion by calculating the non-equilibrium steady state solutions of the model at, and between, its microscopic and macroscopic limits. For the macroscopic picture, we u…
Complete energy conversion between light beams carrying orbital angular momentum using coherent population trapping for a coherently driven double-Λatom-light coupling
A shortcut to adiabaticity (STA) is concerned with the fast and robust manipulation of the dynamics of a quantum system that reproduces the effect of an adiabatic process. A recently proposed method enables the generation of shortcuts from a prescribed slow dynamics by simply rescaling the time variable of the quantum evolution operator [B. L. Bernardo, Phys. Rev. Research 2, 013133 (2020)]. This time-rescaling method does not demand knowledge about the eigenvalues and eigenstates of the Hamiltonian, and in many cases no additional coupling fields. Here, we use this approach to study the probl…
