相关论文: Population Inversion Induced by Resonant States in…
The build-up of exciton populations in resonantly laser excited semiconductors is studied microscopically. For excitation at the $2s$-exciton resonance, it is shown that polarization with a strict $s$-type radial symmetry can be efficiently…
Bare-state population inversion is demonstrated in a two-level system with all dipole matrix elements nonzero. A laser field is resonantly driving the sample whereas a second weaker and lower frequency coherent field additionally pumps it…
We predict a mechanism for achieving complete population inversion in a continuously driven InAs/GaAs semiconductor quantum dot featuring $V$-type transitions. This highly nonequilibrium steady state is enabled by the interplay between…
Motivated by recent experiments, which demonstrated lasing and cooling of the electromagnetic modes in a resonator coupled to a superconducting qubit, we describe the specific mechanisms creating the population inversion, and we study the…
We show how population inversion (PI) occurs in a two-level system (TLS) while measuring its charge using a capacitively coupled superconducting single-electron transistor (SSET), biased in the subgap regime, where the current through the…
Microwave resonances between discrete macroscopically distinct quantum states with single photon and multiphoton absorption are observed in a strongly driven radio frequency superconducting quantum interference device flux qubit. The…
In two-dimensional (2D) electron systems, an off-resonant high-frequency circularly polarized electromagnetic field can induce the quasi-stationary bound electron states of repulsive scatterers. As a consequence, the resonant scattering of…
The semi-classical solution of the three state system is considered to study the population inversion at and away from resonance. At resonance, it is shown that if the system is initially populated either in the upper or in the lower level,…
We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP and Ge in THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of…
We study a double quantum dot system coherently coupled to an electromagnetic resonator. A current through the dot system can create a population inversion in the dot levels and, within a narrow resonance window, a lasing state in the…
Landau level lasers have the advantage of tunability of the laser frequency by means of the external magnetic field. The crucial prerequisite of such a laser is a population inversion between optically coupled Landau levels. Efficient…
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…
We distinguish different mechanisms for population inversion in flux qubits driven by dc+ac magnetic fields. We show that for driving amplitudes such that there are Landau-Zener-St\"uckelberg intereferences, it is possible to have…
Quantum systems with sublevel structures prevent full population inversion from one manifold of sublevels to the other using strong ultrafast resonant pulses. In this work we explain the mechanism by which this population transfer is…
Semi-analytical predictions for the transients of spin-dependent transport and recombination rates through localized states in semiconductors during coherent electron spin excitation are made for the case of weakly spin-coupled charge…
The generation of an out-of-equilibrium population of spin-polarized carriers is a keystone process for quantum technologies and spintronics alike. It can be achieved through the so-called optical spin orientation by exciting the material…
Coherent population trapping is shown to occur in a driven symmetric double-well potential in the strong-field regime. The system parameters have been chosen to reproduce the $0^{-}\leftrightarrow 3^{+}$ transition of the inversion mode of…
We study a double quantum dot system coherently coupled to an electromagnetic resonator. By suitably biasing the system, a population inversion can be created between the dot levels. The resulting lasing state exists within a narrow…
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…
It is shown that the traditional approach for consideration of recombination under condition of steady-state current in the absence of external carrier generation is internally contradictory. Sometimes the approach leads to obviously…