Theory of Spontaneous and Stimulated Emission in Two Band Intrinsic Semiconductor

1997 ◽  
Vol 11 (11) ◽  
pp. 493-502
Author(s):  
Vladislav Cheltsov
Keyword(s):  
Evolution Operator ◽  
Chemical Potential ◽  
Operator Method ◽  
Single Mode ◽  
Excitation Level ◽  
Stimulated Emission ◽  
Quasi Equilibrium ◽  
Intrinsic Semiconductor ◽  
Einstein Distribution ◽  
Bose Einstein

The behavior of a single mode of radiation field coupled to an excited two band intrinsic semiconductor has been investigated with the help of the commutator version of evolution operator method. As dependent on the excitation level three states of the field has been shown to exist: the equilibrium with the number of photons determined by the Bose–Einstein distribution with nonzero chemical potential; the quasi-equilibrium with the average number of photons equal to unity and accompanied by fluctuations; the state of photon avalanche.

scholarly journals Stimulated emission of relic gravitons and their super-Poissonian statistics

2019 ◽  
Vol 34 (23) ◽  
pp. 1950185 ◽  
Author(s):  
Massimo Giovannini
Keyword(s):  
Coherent State ◽  
Second Order ◽  
Stimulated Emission ◽  
Initial State ◽  
Einstein Distribution ◽  
Hubble Radius ◽  
Initial States ◽  
Bose Einstein ◽  
Final Degree ◽  
Poissonian Statistics

The degree of second-order coherence of the relic gravitons produced from the vacuum is super-Poissonian and larger than in the case of a chaotic source characterized by a Bose–Einstein distribution. If the initial state does not minimize the tensor Hamiltonian and has a dispersion smaller than its averaged multiplicity, the overall statistics is by definition sub-Poissonian. Depending on the nature of the sub-Poissonian initial state, the final degree of second-order coherence of the quanta produced by stimulated emission may diminish (possibly even below the characteristic value of a chaotic source) but it always remains larger than one (i.e. super-Poissonian). When the initial statistics is Poissonian (like in the case of a coherent state or for a mixed state weighted by a Poisson distribution) the degree of second-order coherence of the produced gravitons is still super-Poissonian. Even though the quantum origin of the relic gravitons inside the Hubble radius can be effectively disambiguated by looking at the corresponding Hanbury Brown–Twiss correlations, the final distributions caused by different initial states maintain their super-Poissonian character which cannot be altered.

Bose–Einstein condensation of spin wave quanta at room temperature

2011 ◽  
Vol 369 (1951) ◽  
pp. 3575-3587 ◽  
Author(s):  
O. Dzyapko ◽  
V. E. Demidov ◽  
G. A. Melkov ◽  
S. O. Demokritov
Keyword(s):  
Room Temperature ◽  
Chemical Potential ◽  
Spin Waves ◽  
Einstein Condensation ◽  
Quasi Equilibrium ◽  
Magnetic Media ◽  
Bose Einstein Condensation ◽  
Garnet Films ◽  
Iron Garnet ◽  
Bose Einstein

Spin waves are delocalized excitations of magnetic media that mainly determine their magnetic dynamics and thermodynamics at temperatures far below the critical one. The quantum-mechanical counterparts of spin waves are magnons, which can be considered as a gas of weakly interacting bosonic quasi-particles. Here, we discuss the room-temperature kinetics and thermodynamics of the magnon gas in yttrium iron garnet films driven by parametric microwave pumping. We show that for high enough pumping powers, the thermalization of the driven gas results in a quasi-equilibrium state described by Bose–Einstein statistics with a non-zero chemical potential. Further increases of the pumping power cause a Bose–Einstein condensation documented by an observation of the magnon accumulation at the lowest energy level. Using the sensitivity of the Brillouin light scattering spectroscopy to the degree of coherence of the scattering magnons, we confirm the spontaneous emergence of coherence of the magnons accumulated at the bottom of the spectrum, occurring if their density exceeds a critical value.

scholarly journals On the Chemical Potential of Ideal Fermi and Bose Gases

2019 ◽  
Vol 197 (5-6) ◽  
pp. 412-444 ◽  
Author(s):  
Brian Cowan
Keyword(s):  
Chemical Potential ◽  
Arbitrary Order ◽  
Distribution Functions ◽  
Temperature Series ◽  
Quantum Gases ◽  
Series Expansions ◽  
Bose Gases ◽  
Chemical Potentials ◽  
Einstein Distribution ◽  
Bose Einstein

Abstract Knowledge of the chemical potential is essential in application of the Fermi–Dirac and the Bose–Einstein distribution functions for the calculation of properties of quantum gases. We give expressions for the chemical potential of ideal Fermi and Bose gases in 1, 2 and 3 dimensions in terms of inverse polylogarithm functions. We provide Mathematica functions for these chemical potentials together with low- and high-temperature series expansions. In the 3d Bose case we give also expansions about $$T_{{{{\mathrm {B}}}}}$$ T B . The Mathematica routines for the series allow calculation to arbitrary order.

scholarly journals On the Existence of Bright Solitons in Cubic-Quintic Nonlinear Schrödinger Equation with Inhomogeneous Nonlinearity

2008 ◽  
Vol 2008 ◽  
pp. 1-14 ◽  
Author(s):  
Juan Belmonte-Beitia
Keyword(s):  
Schrödinger Equation ◽  
Nonlinear Schrödinger Equation ◽  
Bifurcation Theory ◽  
Schrodinger Equation ◽  
Chemical Potential ◽  
Soliton Solutions ◽  
Nonlinear Schrodinger Equation ◽  
Nonlinear Schrödinger ◽  
Bose Einstein ◽  
Quintic Nonlinear Schrödinger Equation

We give a proof of the existence of stationary bright soliton solutions of the cubic-quintic nonlinear Schrödinger equation with inhomogeneous nonlinearity. By using bifurcation theory, we prove that the norm of the positive solution goes to zero as the parameterλ, called chemical potential in the Bose-Einstein condensates' literature, tends to zero. Moreover, we solve the time-dependent cubic-quintic nonlinear Schrödinger equation with inhomogeneous nonlinearities by using a numerical method.

scholarly journals Chemical potential standard for atomic Bose–Einstein condensates

2003 ◽  
Vol 5 ◽  
pp. 94-94 ◽  
Author(s):  
Sigmund Kohler ◽  
Fernando Sols
Keyword(s):  
Chemical Potential ◽  
Bose Einstein

scholarly journals Evidence for spin current driven Bose-Einstein condensation of magnons

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Divinskiy ◽  
H. Merbouche ◽  
V. E. Demidov ◽  
K. O. Nikolaev ◽  
L. Soumah ◽  
...  
Keyword(s):  
Room Temperature ◽  
Chemical Potential ◽  
Spin Current ◽  
Einstein Condensation ◽  
Electronic Control ◽  
Spintronic Devices ◽  
Bose Einstein Condensation ◽  
Magnetic Insulators ◽  
Spatially Extended ◽  
Bose Einstein

AbstractThe quanta of magnetic excitations – magnons – are known for their unique ability to undergo Bose-Einstein condensation at room temperature. This fascinating phenomenon reveals itself as a spontaneous formation of a coherent state under the influence of incoherent stimuli. Spin currents have been predicted to offer electronic control of Bose-Einstein condensates, but this phenomenon has not been experimentally evidenced up to now. Here we show that current-driven Bose-Einstein condensation can be achieved in nanometer-thick films of magnetic insulators with tailored nonlinearities and minimized magnon interactions. We demonstrate that, above a certain threshold, magnons injected by the spin current overpopulate the lowest-energy level forming a highly coherent spatially extended state. We quantify the chemical potential of the driven magnon gas and show that, at the critical current, it reaches the energy of the lowest magnon level. Our results pave the way for implementation of integrated microscopic quantum magnonic and spintronic devices.

Sign in / Sign up

Export Citation Format

Share Document