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Quantum cascade lasers are of high interest in the scientific community due to unique applications utilizing the emission in mid-IR range. The possible designs of QCL are quite limited and require careful engineering to overcome some…

In this work, we provide a simplified theoretical analytical estimation of the quantum cascade laser build-up time, accurately taking into account the main effects: the QCL overheating during the pump pulse and the photon mode filling…

n-type Ge/SiGe terahertz quantum cascade laser are investigated using non-equilibrium Green's functions calculations. We compare the temperature dependence of the terahertz gain properties with an equivalent GaAs/AlGaAs QCL design. In the…

Mesoscale and Nanoscale Physics · Physics 2019-05-01 T. Grange , D. Stark , G. Scalari , J. Faist , L. Persichetti , L. Di Gaspare , M. De Seta , M. Ortolani , D. J. Paul , G. Capellini , S. Birner , M. Virgilio

Quantum Cascade Lasers (QCLs) are generally designed to avoid negative differential conductivity (NDC) in the vicinity of the operation point in order to prevent instabilities. We demonstrate, that the threshold condition is possible under…

Mesoscale and Nanoscale Physics · Physics 2018-08-29 David O. Winge , Emmanuel Dupont , Andreas Wacker

Recent theoretical predictions hint at an implementation of a superradiant laser based on narrow optical clock transitions by using a filtered thermal beam at high density. Corresponding numerical studies give encouraging results but the…

Atomic Physics · Physics 2023-08-11 Martin Fasser , Christoph Hotter , David Plankensteiner , Helmut Ritsch

Extending the temperature limits of quantum coherence in the system representing a chain of coupled two-level systems (TLS) exposed to an electromagnetic field is complicated due to the adverse influence of noise. Such a system frequently…

Mesoscale and Nanoscale Physics · Physics 2024-07-16 Serhii Shafraniuk

We perform a quantitative analysis of the cooling dynamics of three-level atomic systems interacting with two distinct lasers. Employing sparse-matrix techniques, we find numerical solutions to the fully quantized master equation in steady…

Atomic Physics · Physics 2009-11-13 Josh W. Dunn , J. W. Thomsen , Chris H. Greene , Flavio C. Cruz

QCD at finite temperature and density is becoming increasingly important for various experimental programmes, ranging from heavy ion physics to astro-particle physics. The non-perturbative nature of non-abelian quantum field theories at…

High Energy Physics - Lattice · Physics 2009-11-02 Owe Philipsen

In this review the debated rapport between thermodynamics and quantum mechanics is addressed in the framework of the theory of periodically-driven/controlled quantum-thermodynamic machines. The basic model studied here is that of a…

Quantum Physics · Physics 2015-09-15 D. Gelbwaser-Klimovsky , Wolfgang Niedenzu , Gershon Kurizki

The current understanding of finite temperature phase transitions in QCD is reviewed. A critical discussion of refined phase transition criteria in numerical lattice simulations and of analytical tools going beyond the mean-field level in…

High Energy Physics - Lattice · Physics 2008-11-26 Hildegard Meyer-Ortmanns

We theoretically study the quantum speed limits (QSLs) of a qubit system coupled to a thermal dephasing environment with an Ohmic-like spectral density. Based on the geometric QSLs time bound, which is derived by employing the trace…

Quantum Physics · Physics 2025-04-08 Xiangji Cai , Yanyan Feng , Jing Ren , Kang Lan , Shuning Sun , Xiangjia Meng , Artur Czerwinski

The temperature dependence of the thermal rate constant for the reaction Cl($^2$P) + CH$_4$ $\rightarrow$ CH$_3$ + HCl is calculated using a Gaussian Process machine learning (ML) approach to train on and predict thermal rate constants over…

Chemical Physics · Physics 2022-08-23 Paul L. Houston , Apurba Nandi , Joel M. Bowman

Taking into account the temperature gradients in solar cells, it is shown that their efficiency can be increased beyond the Shockley-Queisser limit (J. Appl. Phys. 32 (1961) 510). The driving force for this gain is the temperature gradient…

Materials Science · Physics 2015-06-24 Stefan Kettemann , Jean-Francois Guillemoles

We discuss radiative corrections to how quark mass thresholds are crossed, as a function of the temperature, in basic thermodynamic observables such as the pressure, the energy and entropy densities, and the heat capacity of high…

High Energy Physics - Phenomenology · Physics 2011-08-01 M. Laine , Y. Schroder

Two parameters that have a strong influence on the finite temperature QCD transition, and play an important role in various physical scenarios are the quark density and the external magnetic field. The effect of these parameters on the…

High Energy Physics - Lattice · Physics 2015-06-17 G. Endrodi

We employ semiclassical theoretical analysis to study laser cooling of free atoms using three-level cascade transitions, where the upper transition is much weaker than the lower one. This represents an alternate cooling scheme, particularly…

Atomic Physics · Physics 2015-06-16 Flavio C. Cruz , Michael L. Sundheimer , Wictor C. Magno

One of the principal objectives of quantum thermodynamics is to explore quantum effects and their potential beneficial role in thermodynamic tasks like work extraction or refrigeration. So far, even though several papers have already shown…

Quantum Physics · Physics 2019-04-22 C. L. Latune , I. Sinayskiy , F. Petruccione

A laser can be understood as thermodynamic engine converting heat to a coherent single mode field close to Carnot efficiency. From this perspective spectral shaping of the excitation light generates a higher effective temperature on the…

Quantum Physics · Physics 2013-05-30 K. Sandner , H. Ritsch

The temporal pseudoscalar meson correlation function in a QCD plasma is investigated in a range of temperatures exceeding $T_c$ and yet of experimental interest. Only the flavour-singlet channel is considered and the imaginary time…

High Energy Physics - Phenomenology · Physics 2009-11-10 W. M. Alberico , A. Beraudo , A. Molinari

We investigate room temperature lasing of terahertz quantum cascade lasers using quantum dot chains as active material suitable for wireless communication and imaging technologies. Bandstructure calculations for such extended systems of…

Mesoscale and Nanoscale Physics · Physics 2021-03-10 Alexander Mittelstädt , Ludwig A. Th. Greif , Stefan T. Jagsch , Andrei Schliwa
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