Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation
In quantum field theory, bare particles are dressed by a cloud of virtual particles to form physical particles. The virtual particles affect properties such as the mass and charge of the physical particles, and it is only these modified properties that can be measured in experiments, not the propert...
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IOP Publishing
2017-01-01
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| Series: | New Journal of Physics |
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| Online Access: | https://doi.org/10.1088/1367-2630/aa6cd7 |
| _version_ | 1797750814537678848 |
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| author | Omar Di Stefano Roberto Stassi Luigi Garziano Anton Frisk Kockum Salvatore Savasta Franco Nori |
| author_facet | Omar Di Stefano Roberto Stassi Luigi Garziano Anton Frisk Kockum Salvatore Savasta Franco Nori |
| author_sort | Omar Di Stefano |
| collection | DOAJ |
| description | In quantum field theory, bare particles are dressed by a cloud of virtual particles to form physical particles. The virtual particles affect properties such as the mass and charge of the physical particles, and it is only these modified properties that can be measured in experiments, not the properties of the bare particles. The influence of virtual particles is prominent in the ultrastrong-coupling regime of cavity quantum electrodynamics (QED), which has recently been realised in several condensed-matter systems. In some of these systems, the effective interaction between atom-like transitions and the cavity photons can be switched on or off by external control pulses. This offers unprecedented possibilities for exploring quantum vacuum fluctuations and the relation between physical and bare particles. We consider a single three-level quantum system coupled to an optical resonator. Here we show that, by applying external electromagnetic pulses of suitable amplitude and frequency, each virtual photon dressing a physical excitation in cavity-QED systems can be converted into a physical observable photon, and back again. In this way, the hidden relationship between the bare and the physical excitations can be unravelled and becomes experimentally testable. The conversion between virtual and physical photons can be clearly pictured using Feynman diagrams with cut loops. |
| first_indexed | 2024-03-12T16:38:20Z |
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| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:38:20Z |
| publishDate | 2017-01-01 |
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| series | New Journal of Physics |
| spelling | doaj.art-392bb9ccf1b141b8b043427e40ae7cd82023-08-08T14:37:11ZengIOP PublishingNew Journal of Physics1367-26302017-01-0119505301010.1088/1367-2630/aa6cd7Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitationOmar Di Stefano0https://orcid.org/0000-0002-3054-272XRoberto Stassi1Luigi Garziano2Anton Frisk Kockum3Salvatore Savasta4Franco Nori5MIFT—Dipartimento di Scienze Matematiche e Informatiche Scienze Fisiche e Scienze della Terra, Università di Messina , I-98166 Messina, Italy; CEMS, RIKEN, Saitama 351-0198, JapanCEMS, RIKEN, Saitama 351-0198, JapanUniversity of Southampton , Southampton, SO17 1BJ, United KingdomCEMS, RIKEN, Saitama 351-0198, JapanMIFT—Dipartimento di Scienze Matematiche e Informatiche Scienze Fisiche e Scienze della Terra, Università di Messina , I-98166 Messina, Italy; CEMS, RIKEN, Saitama 351-0198, JapanCEMS, RIKEN, Saitama 351-0198, Japan; Physics Department, The University of Michigan , Ann Arbor, Michigan 48109-1040, United States of AmericaIn quantum field theory, bare particles are dressed by a cloud of virtual particles to form physical particles. The virtual particles affect properties such as the mass and charge of the physical particles, and it is only these modified properties that can be measured in experiments, not the properties of the bare particles. The influence of virtual particles is prominent in the ultrastrong-coupling regime of cavity quantum electrodynamics (QED), which has recently been realised in several condensed-matter systems. In some of these systems, the effective interaction between atom-like transitions and the cavity photons can be switched on or off by external control pulses. This offers unprecedented possibilities for exploring quantum vacuum fluctuations and the relation between physical and bare particles. We consider a single three-level quantum system coupled to an optical resonator. Here we show that, by applying external electromagnetic pulses of suitable amplitude and frequency, each virtual photon dressing a physical excitation in cavity-QED systems can be converted into a physical observable photon, and back again. In this way, the hidden relationship between the bare and the physical excitations can be unravelled and becomes experimentally testable. The conversion between virtual and physical photons can be clearly pictured using Feynman diagrams with cut loops.https://doi.org/10.1088/1367-2630/aa6cd7ultrastrong-coupling regimevirtual particlesFeynman diagramscavity-QEDquantum vacuum fluctuationsthree-level quantum system |
| spellingShingle | Omar Di Stefano Roberto Stassi Luigi Garziano Anton Frisk Kockum Salvatore Savasta Franco Nori Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation New Journal of Physics ultrastrong-coupling regime virtual particles Feynman diagrams cavity-QED quantum vacuum fluctuations three-level quantum system |
| title | Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation |
| title_full | Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation |
| title_fullStr | Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation |
| title_full_unstemmed | Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation |
| title_short | Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation |
| title_sort | feynman diagrams approach to the quantum rabi model for ultrastrong cavity qed stimulated emission and reabsorption of virtual particles dressing a physical excitation |
| topic | ultrastrong-coupling regime virtual particles Feynman diagrams cavity-QED quantum vacuum fluctuations three-level quantum system |
| url | https://doi.org/10.1088/1367-2630/aa6cd7 |
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