Two-photon interference spectra induced by a bichromatic field in the excited state of a single three-level ion

1992 ◽  
Vol 70 (1) ◽  
pp. 1-23 ◽  
Author(s):  
Constantine Mavroyannis
Keyword(s):  
Excited State ◽  
Ground State ◽  
Correlation Functions ◽  
Stark Effect ◽  
Stimulated Emission ◽  
Laser Fields ◽  
Two Photon ◽  
Dynamic Stark Effect ◽  
Two Peaks ◽  
Photon Resonance

We consider the interference spectra arising from the competition between a spontaneous process and two processes induced by two laser fields, which are coupled with a three-level atom in the "Λ" configuration. In the low-intensity limit of both laser fields and on two-photon resonance, the frequency profiles of the two peaks, which arise from the spontaneous and induced processes, cancel each other out completely at the center of the line for zero detuning and at the finite values of the detuning as well. At high intensities of the laser fields and on two-photon resonance, the dynamic Stark effect dominates the spectra of the excited state of the atom. Expressions for the interference spectra and correlation functions are derived, which describe the physical process of the absorption of a laser photon at two different times by the ground state of the atom. Interference spectra and correlation functions are calculated for the two-photon off-resonance and for the proces of the absorption of a photon by the ground state of the atom. In this case, the intensities of the frequency dips take negative values indicating that stimulated emission prevails for certain values of the detunings. Using values for the parameters involved close to those for Ba+, the computed two-photon resonance and off-resonance spectra are graphically presented and discussed.

Interference spectra in a two-level atom

1990 ◽  
Vol 68 (12) ◽  
pp. 1389-1395 ◽  
Author(s):  
Constantine Mavroyannis
Keyword(s):  
Excited State ◽  
High Intensity ◽  
Laser Field ◽  
Stark Effect ◽  
Ground States ◽  
Spectral Functions ◽  
Laser Photon ◽  
Level Atom ◽  
Dynamic Stark Effect ◽  
Two Peaks

We have considered the interference spectra arising from the competition between a spontaneous process and one induced by a laser field in a two-level atom. Expressions for the spectral functions have been derived describing the spectra of the excited and ground states of the atom in the low- and high-intensity limit of the laser field. For the excited-state spectra in the low-intensity limit, the frequency profiles of the two peaks, which arise from the spontaneous and the induced processes, cancel each other out completely near the center of the line, while for the ground state the induced process dominates. For finite values of the detuning, the spectra of the excited state consist of two peaks, which have positive and negative frequency profiles, respectively. The computed spectra have been graphically presented and discussed. In the high-intensity limit, the dynamic Stark effect dominates the spectra of the excited and ground states of the atom. Expressions for the correlation functions have been derived that describe the emission or the absorption of a laser photon at two different times. The derived expressions for the corresponding delay functions in the low- and high-intensity limits have been found to be identical to those recently proposed in the literature. The laser field has been treated as a classical as well as a quantized entity.

Resonance fluorescence spectra from a three level atom interacting with a strong bichromatic field: induced two photon transitions

1983 ◽  
Vol 61 (1) ◽  
pp. 15-29 ◽  
Author(s):  
Douglas A. Hutchinson ◽  
Christine Downie ◽  
Constantine Mavroyannis
Keyword(s):  
Ground State ◽  
Rabi Frequency ◽  
Resonance Fluorescence ◽  
Excitation Spectra ◽  
Laser Fields ◽  
Two Photon ◽  
Photon Transition ◽  
Level Atom ◽  
Photon Excitation ◽  
The One

This investigation describes the interaction of a three level atom with two laser fields. One of the transitions from the ground state is in resonance with twice the frequency of the first laser and the other transition from the ground state is in resonance with the second laser. The Green's function formalism is used to derive expressions from which the induced two photon and one photon excitation spectra are computed. Also, approximate expressions are derived for the excitation spectra in the appropriate frequency regions. These results agree well with the numerical computations based upon the precise expressions. The interference between the two transitions produce some splittings; these splittings depend upon the Rabi frequency of the one photon transition. The intensities of the weak peaks depend upon the ratio of the Rabi frequency of the two photon transition to the frequency of the first laser. Some features of the excitation spectra are interpreted in terms of previous knowledge about the behavior of two level atoms in strong laser fields.

ELECTRON CORRELATION AND PHOTO PHYSICS OF PHENYL SUBSTITUTED POLYACETYLENES

2001 ◽  
Vol 15 (19n20) ◽  
pp. 2793-2798 ◽  
Author(s):  
HARANATH GHOSH ◽  
S. MAZUMDAR ◽  
Alok SHUKLA
Keyword(s):  
Excited State ◽  
Electron Correlation ◽  
Ground State ◽  
Transverse Direction ◽  
Longitudinal Direction ◽  
High Energy ◽  
Electron Interaction ◽  
Many Body ◽  
Photon State ◽  
Two Photon

We investigate theoretically photoluminescence (PL) properties of mono and di-phenyl substituted trans-polyacetylene (t-PA), namely, poly-phenylacetylene (PPA) and poly-diphenylacetylene (PDPA), respectively. PL is a consequence of the occurrence of the two-photon state ( 2Ag ) above the optically excited state ( 1Bu ). Usually, electron correlation leads to confinement of 1Bu as well as the ground state. We show, in contrast, that in phenyl-substituted polyacetylenes electron–electron interactions cause enhanced delocalization of quasiparticles in the optically excited state from the backbone polyene chain into the phenyl groups. This coulomb enhanced delocalization in the transverse direction leads to confinement in the longitudinal direction and causes crossover between the 1Bu and 2Ag . We further show that in the absence of electron repulsion the low energy absorption is x-polarized whereas the high energy absorpion is predominantly y-polarized. In contrast, in presence of many body electron interaction both of them (low and high energy absorptions) are x-polarized. Thus photophysics of PPA/PDPA etc. are consequences of true many body effects.

Induced absorption and stimulated emission in a driven two-level atom

1992 ◽  
Vol 70 (6) ◽  
pp. 427-431 ◽  
Author(s):  
Constantine Mavroyannis
Keyword(s):  
Excited State ◽  
Ground State ◽  
Laser Field ◽  
Low Frequency ◽  
Ultrashort Pulses ◽  
Stimulated Emission ◽  
Spectral Lines ◽  
Laser Photon ◽  
Induced Absorption ◽  
Level Atom

We have considered the induced processes that occur in a driven two-level atom, where a laser photon is absorbed and emitted by the ground and by the excited states of the atom, respectively. In the low-intensity limit of the laser field, the induced spectra arising when a laser photon is absorbed by the ground state of the atom consist of two peaks describing induced-absorption and stimulated-emission processes, respectively, where the former prevails over the latter. Asymmetry of the spectral lines occurs at off-resonance and its extent depends on the detuning of the laser field. The physical, process where a laser photon is emitted by the excited state is the reverse of that arising from the absorption of a laser photon by the ground state of the atom. The former differs from the latter in that the emission of a laser photon by the excited state occurs in the low-frequency regime and that the stimulated-emission process prevails over that of the induced absorption. In this case, amplification of ultrashort pulses is likely to occur without the need of population inversion between the optical transitions. The computed spectra are graphically presented and discussed.

scholarly journals Superadiabatic population transfer in a three-level superconducting circuit

2019 ◽  
Vol 5 (2) ◽  
pp. eaau5999 ◽  
Author(s):  
Antti Vepsäläinen ◽  
Sergey Danilin ◽  
Gheorghe Sorin Paraoanu
Keyword(s):  
Excited State ◽  
Ground State ◽  
Microwave Pulse ◽  
Quantum Information Processing ◽  
Quantum Circuit ◽  
Population Transfer ◽  
Adiabatic Passage ◽  
Two Photon ◽  
Superconducting Circuit ◽  
Stimulated Raman Adiabatic Passage

Adiabatic manipulation of the quantum state is an essential tool in modern quantum information processing. Here, we demonstrate the speedup of the adiabatic population transfer in a three-level superconducting transmon circuit by suppressing the spurious nonadiabatic excitations with an additional two-photon microwave pulse. We apply this superadiabatic method to the stimulated Raman adiabatic passage, realizing fast and robust population transfer from the ground state to the second excited state of the quantum circuit.

scholarly journals Influence of Giant Nuclear-spin Polarisation on Resonant Gamma-ray Absorption and Emission

1998 ◽  
Vol 51 (2) ◽  
pp. 339
Author(s):  
R. N. Shakhmuratov
Keyword(s):  
Excited State ◽  
Nuclear Spin ◽  
Ground State ◽  
Gamma Ray ◽  
Stimulated Emission ◽  
Laser Pumping ◽  
Nuclear Excited State ◽  
Spin Polarisation ◽  
Subsequent Quenching ◽  
Amplification Without Inversion

We propose a new scheme of gamma-quanta amplification without inversion. Laser pumping of electron states creates giant nuclear-spin polarisation via the hyperfine interaction. This results in extreme cooling of the ground-state nuclear spin in a projection which does not absorb both laser pump and gamma-quanta according to selection rules for these transitions. Induced emission from the nuclear excited state is not influenced by the pump. Therefore gamma-quanta travelling inside the pump beam have an opportunity to induce stimulated emission without subsequent quenching by ground state nuclei.

scholarly journals Нелинейное просветление InAs нитевидных нанокристаллов в видимом диапазоне

2020 ◽  
Vol 128 (1) ◽  
pp. 128
Author(s):  
А.С. Кулагина ◽  
А.И. Хребтов ◽  
А.А. Рыжов ◽  
В.В. Данилов ◽  
И.В. Штром ◽  
...  
Keyword(s):  
Room Temperature ◽  
Molecular Beam ◽  
Stark Effect ◽  
Visible Range ◽  
Bohr Radius ◽  
Two Photon ◽  
Photon Excitation ◽  
Dynamic Stark Effect ◽  
Inas Nanowires ◽  
Characteristic Maximum

The spectral and nonlinear optical properties of InAs nanowires suspensions in isopropanol were studied at room temperature. InAs nanowires were synthesized by molecular beam epitaxy. The absorption spectra of suspensions with a characteristic maximum at a wavelength of 235 nm were obtained, as well as Raman spectra in the range 180–280 cm – 1. The nonlinear transmission of InAs nanowires with a diameter less than the Bohr radius of the exciton upon two-photon excitation in the transparency region in the visible range (λ = 468 nm) was studied firstly. The effect of cumulative bleaching was discovered, the manifestation of which is associated with the dynamic Stark effect.

Red to Green Upconversion in Er3+-Doped BaTiO3 Nanorods

2008 ◽  
Vol 8 (12) ◽  
pp. 6564-6568 ◽  
Author(s):  
Márcio A. R. C. Alencar ◽  
Glauco S. Maciel ◽  
Cid B. de Araújo ◽  
Amitava Patra
Keyword(s):  
Excited State ◽  
Excitation Spectrum ◽  
Ground State ◽  
Laser Power ◽  
Excited State Absorption ◽  
Photon Absorption ◽  
Absorption Process ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Upconversion Emissions

We investigated the frequency upconversion (UC) process in BaTiO3:Er3+ nanocrystals for excitation wavelengths in the range 638 to 660 nm. Green upconversion emissions at 526 and 547 nm corresponding to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 to transitions of the Er3+ were observed. The excitation spectrum for UC emissions presented three bands, due to ground state and excited state absorption of Er3+ ions. The UC intensity as a function of the laser power was investigated and it was found this a two-photon absorption process.

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