Cosmological stimulated emission
Abstract We study stimulated emission and absorption of gravitons in a squeezed vacuum state immersed in a thermal radiation bath. Employing one-loop interaction-picture perturbation theory, we track the time evolution of the graviton number operator and its expectation value in the squeezed vacuum,...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2025-07-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-025-14523-0 |
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| _version_ | 1849761386944528384 |
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| author | Atsuhisa Ota |
| author_facet | Atsuhisa Ota |
| author_sort | Atsuhisa Ota |
| collection | DOAJ |
| description | Abstract We study stimulated emission and absorption of gravitons in a squeezed vacuum state immersed in a thermal radiation bath. Employing one-loop interaction-picture perturbation theory, we track the time evolution of the graviton number operator and its expectation value in the squeezed vacuum, which characterizes the inflationary graviton state. In a Minkowski background with a thermal bath as a toy example, we demonstrate that the net graviton emission or absorption rate depends sensitively on the initial squeezing parameters. As a thought experiment, we consider LIGO/Virgo-like detectors operating in radiation at temperatures of order 0.1 GeV and find that graviton occupation numbers at frequencies of order 100 Hz can be significantly enhanced, suggesting a novel mechanism for amplifying gravitational-wave signals. Although these conditions exceed current experimental capabilities, they point toward potential future advances in detection. Extending our analysis to an expanding, radiation-dominated universe, we show that subhorizon gravitons undergo stimulated absorption, while superhorizon modes exhibit secular logarithmic growth, indicating the breakdown of perturbative methods and motivating further investigation. These findings open a new direction for exploring graviton coherence effects in realistic cosmological and laboratory settings. |
| format | Article |
| id | doaj-art-3ff69f762716448f96f2faeda13ee2b0 |
| institution | DOAJ |
| issn | 1434-6052 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj-art-3ff69f762716448f96f2faeda13ee2b02025-08-20T03:06:02ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522025-07-0185711610.1140/epjc/s10052-025-14523-0Cosmological stimulated emissionAtsuhisa Ota0Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics, Chongqing UniversityAbstract We study stimulated emission and absorption of gravitons in a squeezed vacuum state immersed in a thermal radiation bath. Employing one-loop interaction-picture perturbation theory, we track the time evolution of the graviton number operator and its expectation value in the squeezed vacuum, which characterizes the inflationary graviton state. In a Minkowski background with a thermal bath as a toy example, we demonstrate that the net graviton emission or absorption rate depends sensitively on the initial squeezing parameters. As a thought experiment, we consider LIGO/Virgo-like detectors operating in radiation at temperatures of order 0.1 GeV and find that graviton occupation numbers at frequencies of order 100 Hz can be significantly enhanced, suggesting a novel mechanism for amplifying gravitational-wave signals. Although these conditions exceed current experimental capabilities, they point toward potential future advances in detection. Extending our analysis to an expanding, radiation-dominated universe, we show that subhorizon gravitons undergo stimulated absorption, while superhorizon modes exhibit secular logarithmic growth, indicating the breakdown of perturbative methods and motivating further investigation. These findings open a new direction for exploring graviton coherence effects in realistic cosmological and laboratory settings.https://doi.org/10.1140/epjc/s10052-025-14523-0 |
| spellingShingle | Atsuhisa Ota Cosmological stimulated emission European Physical Journal C: Particles and Fields |
| title | Cosmological stimulated emission |
| title_full | Cosmological stimulated emission |
| title_fullStr | Cosmological stimulated emission |
| title_full_unstemmed | Cosmological stimulated emission |
| title_short | Cosmological stimulated emission |
| title_sort | cosmological stimulated emission |
| url | https://doi.org/10.1140/epjc/s10052-025-14523-0 |
| work_keys_str_mv | AT atsuhisaota cosmologicalstimulatedemission |