Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review Letters

Intrinsically Irreversible Multiphoton Laser Gain Mechanisms

Peter B. Sellin, Chung‐Chieh Yu, Jason R. Bochinski, THOMAS W. MOSSBERG

Published Feb 24, 1997• 22 citations
Publisher

Abstract

Single-photon stimulated radiative interactions are universally symmetric relative to emission and absorption. We point out that certain multiphoton stimulated processes, whose completion is dependent on the spontaneous emission of at least one photon, do not behave analogously. The broken symmetry found in such cases invalidates simple correlations between population inversion and laser gain.

DOI
10.1103/physrevlett.78.1432

Related papers

Quantum theory of multiphoton lasers. I. Systems in detailed balance

K. J. McNeil, Daniel F. Walls

A quantum-mechanical model for a multiphoton laser is proposed by an obvious generalization of the usual one-photon laser model. The authors consider a class of lasers which preserve detailed balance. This condition is ensured by assuming a multiphoton loss mechanism for the laser light of the same order as the multiphoton gain from the stimulated emission process. Solutions for the stationary density operator of the light field are obtained by a straightforward generalization of the techniques of Scully and Lamb. The multiphoton laser around threshold exhibits behaviour analogous to a second-order phase transition. A non-thermal distribution of multiphoton laser light is achieved above threshold.

Journal of Physics A Mathematical and General•Jan 1, 1975•68 citations

The thermodynamics of multiphoton processes

G. J. Pert

By considering the thermodynamic equilibrium of a radiation field with matter through multiphoton processes, generalized expressions equivalent to the Einstein and Milne relations for single photon interactions are derived. Mixed stimulated spontaneous effects are predicted with an integral intensity power law index less then n, the order of the process.

Journal of Physics B Atomic and Molecular Physics•Sep 1, 1971•0 citations

Lasers without inversion: one-photon stimulated emission in a three-level atom

Constantine Mavroyannis

I consider light amplification arising from the competition between absorption and stimulated emission of an excitation, which is induced by a laser field at low intensities interacting with a three-level atom. The lifetime of the induced excitation is 105–106 times longer than those of spontaneously emitted excitations. Conditions are established under which the stimulated emission prevails over the induced absorption, and the net negative intensity is 102–103 times greater than those of spontaneously emitted excitations, indicating that significant amplification occurs near the frequency of the laser field. PACS numbers: 32.80-t, 42.50.-p, 42.50H2

Journal of the Optical Society of America B•Dec 1, 1993•3 citations

Symmetries in the optical Bloch equations and multiphoton processes

Bruno Zambon

The optical Bloch equations exhibit symmetries that are directly related to the probabilities of the processes of absorption and stimulated emission. As a matter of fact, a picture similar to that holding for a two-level system can be recovered also in multilevel systems and, in particular, for any multiphoton process tuned between a given couple of levels. Thus, new quantities, such as the generalized Einstein B coefficients, directly related to the probabilities of the involved process, and atomic level indicators, whose inversion signals the existence of gain for that given process, can be defined. It is shown how these lead to valuable conceptual simplifications and to the disclosure of new insights into some popular problems of quantum optics. In particular, the issue of an efficient gain process to be realized within a multilevel atom-field configuration, a problem closely related to the widely investigated problem of lasing configurations without population inversion, can be viewed entirely as a rate problem and therefore analyzed with increased confidence.

Physical Review A•Apr 19, 2001•0 citations

Non-Reciprocity of Autoionizing Interferences: Lasers Without Inversion

Stephen E. Harris

Interferences of autoionizing lines may reduce or eliminate absorption of lower level atoms. Stimulated emission shows no such interferences, thereby allowing laser gain without population inversion.

Short Wavelength Coherent Radiation: Generation and Applications•Jan 1, 1988•0 citations

Spontaneous emission from driven polar quantum systems

Piotr Gładysz, Karolina Słowik, Francesco V. Pepe

We investigate spontaneous radiative processes in a driven polar two-level system whose interaction with the laser field is dominated by broken inversion symmetry rather than by the usual transition dipole coupling. Using a polaron transformation, we derive the dressed eigenstates of the atom-laser system and show that their longitudinal coupling reshapes the spectrum into two displaced harmonic ladders. We then analyze spontaneous transitions induced by a bosonic reservoir, and obtain transition rates that depend on both the laser parameters and the overlap between displaced field states. In the few-photon regime, we identify conditions under which spontaneous emission from the excited state can be strongly suppressed, thereby extending its lifetime, as well as regimes where the ladder structure enables spontaneous absorption from the ground state. In the semiclassical limit of a strong coherent drive, we derive compact analytical expressions for the total transition rates and show that they are governed by Bessel-function weights associated with multiphoton channels. Our results show how broken inversion symmetry qualitatively modifies decay dynamics and radiative cascades, and they establish driven polar quantum systems as a platform for controlling spontaneous light emission beyond the standard inversion-symmetric setting.

quant-pharXiv:2604.18763•Physical Review Research•Apr 22, 2026•0 citations
Single-photon stimulated radiative interactions are universally symmetric relative to emission and absorption. We point out that certain multiphoton stimulated processes, whose completion is dependent on the spontaneous emission of at least one photon, do not behave analogously. The broken symmetry found in such cases invalidates simple correlations between population inversion and laser gain.
A quantum-mechanical model for a multiphoton laser is proposed by an obvious generalization of the usual one-photon laser model. The authors consider a class of lasers which preserve detailed balance. This condition is ensured by assuming a multiphoton loss mechanism for the laser light of the same order as the multiphoton gain from the stimulated emission process. Solutions for the stationary density operator of the light field are obtained by a straightforward generalization of the techniques of Scully and Lamb. The multiphoton laser around threshold exhibits behaviour analogous to a second-order phase transition. A non-thermal distribution of multiphoton laser light is achieved above threshold.
I consider light amplification arising from the competition between absorption and stimulated emission of an excitation, which is induced by a laser field at low intensities interacting with a three-level atom. The lifetime of the induced excitation is 105–106 times longer than those of spontaneously emitted excitations. Conditions are established under which the stimulated emission prevails over the induced absorption, and the net negative intensity is 102–103 times greater than those of spontaneously emitted excitations, indicating that significant amplification occurs near the frequency of the laser field. PACS numbers: 32.80-t, 42.50.-p, 42.50H2
The optical Bloch equations exhibit symmetries that are directly related to the probabilities of the processes of absorption and stimulated emission. As a matter of fact, a picture similar to that holding for a two-level system can be recovered also in multilevel systems and, in particular, for any multiphoton process tuned between a given couple of levels. Thus, new quantities, such as the generalized Einstein B coefficients, directly related to the probabilities of the involved process, and atomic level indicators, whose inversion signals the existence of gain for that given process, can be defined. It is shown how these lead to valuable conceptual simplifications and to the disclosure of new insights into some popular problems of quantum optics. In particular, the issue of an efficient gain process to be realized within a multilevel atom-field configuration, a problem closely related to the widely investigated problem of lasing configurations without population inversion, can be viewed entirely as a rate problem and therefore analyzed with increased confidence.
We investigate spontaneous radiative processes in a driven polar two-level system whose interaction with the laser field is dominated by broken inversion symmetry rather than by the usual transition dipole coupling. Using a polaron transformation, we derive the dressed eigenstates of the atom-laser system and show that their longitudinal coupling reshapes the spectrum into two displaced harmonic ladders. We then analyze spontaneous transitions induced by a bosonic reservoir, and obtain transition rates that depend on both the laser parameters and the overlap between displaced field states. In the few-photon regime, we identify conditions under which spontaneous emission from the excited state can be strongly suppressed, thereby extending its lifetime, as well as regimes where the ladder structure enables spontaneous absorption from the ground state. In the semiclassical limit of a strong coherent drive, we derive compact analytical expressions for the total transition rates and show that they are governed by Bessel-function weights associated with multiphoton channels. Our results show how broken inversion symmetry qualitatively modifies decay dynamics and radiative cascades, and they establish driven polar quantum systems as a platform for controlling spontaneous light emission beyond the standard inversion-symmetric setting.