Dokument: Frequency metrology of HD+ by ultra-high resolution rotational spectroscopy
| Titel: | Frequency metrology of HD+ by ultra-high resolution rotational spectroscopy | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=56418 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20210602-080538-5 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Alighanbari, Soroosh [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Schiller, Stephan [Betreuer/Doktorvater] Prof. Dr. Schmitt, Michael [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibungen: | The hydrogen molecular ion (MHI) is the simplest three-body bound quantum mechanical system, and therefore, it is an interesting system for advanced atomic and molecular physics studies. The rotational and vibrational energy levels of the MHIs depend on fundamental constants of atomic and nuclear physics, and measurement of transition frequencies between these levels enables determination of: Rydberg constant, electron-proton mass ratio, proton-deuteron mass ratio, proton radius, deuteron radius, and quadrupole moment of the deuteron. Spectroscopy of the MHIs is a complementary independent approach to link between hydrogen spectroscopy and mass spectrometry of fundamental particles. Besides, precision spectroscopy of the MHIs can be used to search for new physics beyond the standard model of particle physics, through search for a hypothetical fifth force between the nuclei.
The ab initio theory of the MHIs has been improved significantly in last two decades, through a highly precise calculation of the energies and wave functions of the three-body Schrödinger problem together with perturbation calculation of the relativistic and QED corrections. Currently, the uncertainty of the ab initio theory of the MHIs is 13*10^-12 for rotational and 7.5*10^-12 for vibrational transitions. On the experimental side, laser spectroscopy of trapped and sympathetically cooled molecular ions enhanced spectroscopic resolution and accuracy. However, residual Doppler broadening in ion clusters limits the achievable resolution. Besides, unresolved hyperfine structure complicates interpretation of observed experimental transitions. Here, we invented and demonstrated a novel approach that enables sub-Doppler rotational spectroscopy. The strong radial spatial confinement of molecular ions in a linear Paul trap, with excitation direction transverse to the axis of trap, provides the Lamb-Dicke regime. This approach enables Doppler-free spectroscopy of transitions with wavelength larger than motional amplitude of the molecular ions. We measured the rotational transition of the HD+ ions at 1.3 THz, where we achieved a fractional uncertainty of 1.3*10^-11. Compared to previous experiments using the sympathetic cooling method, we achieve a 100 times higher precision. This enormous improvement has led to the most accurate verification of the three-body quantum problem to date. Theory and experiment agree within an uncertainty of 5*10^-11, where the agreement is limited by the uncertainty of the fundamental constants, required to specify the theoretical energy values. Our result confirms the most recent (CODATA2018) values of the relevant fundamental constants. The experimental results and theory also allow to precisely determine the combination of fundamental constants R_{\infty} m_{e} (1/m_{p}+1/m_{d}), with fractional uncertainty of 1.9*10^-11, which is in agreement but 2.4 times more precise than CODATA2018. Alternatively, we use the Rydberg constant, electron mass, deuteron mass, and charge radii from CODATA2018, and obtain the proton mass. We also deduce the value for the electric quadrupole moment of the deuteron by comparison of the theoretical and experimental spin averaged frequencies. We used the experiment-theory agreement to set an upper limit on a hypothetical spin-independent fifth force between proton and deuteron, with a factor of 21 improvement compared to previous bounds from MHI spectroscopy.The hydrogen molecular ion (MHI) is the simplest three-body bound quantum mechanical system, and therefore, it is an interesting system for advanced atomic and molecular physics studies. The rotational and vibrational energy levels of the MHIs depend on fundamental constants of atomic and nuclear physics, and measurement of transition frequencies between these levels enables determination of: Rydberg constant, electron-proton mass ratio, proton-deuteron mass ratio, proton radius, deuteron radius, and quadrupole moment of the deuteron. Spectroscopy of the MHIs is a complementary independent approach to link between hydrogen spectroscopy and mass spectrometry of fundamental particles. Besides, precision spectroscopy of the MHIs can be used to search for new physics beyond the standard model of particle physics, through search for a hypothetical fifth force between the nuclei. The ab initio theory of the MHIs has been improved significantly in last two decades, through a highly precise calculation of the energies and wave functions of the three-body Schrödinger problem together with perturbation calculation of the relativistic and QED corrections. Currently, the uncertainty of the ab initio theory of the MHIs is 13*10^-12 for rotational and 7.5*10^-12 for vibrational transitions. On the experimental side, laser spectroscopy of trapped and sympathetically cooled molecular ions enhanced spectroscopic resolution and accuracy. However, residual Doppler broadening in ion clusters limits the achievable resolution. Besides, unresolved hyperfine structure complicates interpretation of observed experimental transitions. Here, we invented and demonstrated a novel approach that enables sub-Doppler rotational spectroscopy. The strong radial spatial confinement of molecular ions in a linear Paul trap, with excitation direction transverse to the axis of trap, provides the Lamb-Dicke regime. This approach enables Doppler-free spectroscopy of transitions with wavelength larger than motional amplitude of the molecular ions. We measured the rotational transition of the HD+ ions at 1.3 THz, where we achieved a fractional uncertainty of 1.3*10^-11. Compared to previous experiments using the sympathetic cooling method, we achieve a 100 times higher precision. This enormous improvement has led to the most accurate verification of the three-body quantum problem to date. Theory and experiment agree within an uncertainty of 5*10^-11, where the agreement is limited by the uncertainty of the fundamental constants, required to specify the theoretical energy values. Our result confirms the most recent (CODATA2018) values of the relevant fundamental constants. The experimental results and theory also allow to precisely determine the combination of fundamental constants R_{\infty} m_{e} (1/m_{p}+1/m_{d}), with fractional uncertainty of 1.9*10^-11, which is in agreement but 2.4 times more precise than CODATA2018. Alternatively, we use the Rydberg constant, electron mass, deuteron mass, and charge radii from CODATA2018, and obtain the proton mass. We also deduce the value for the electric quadrupole moment of the deuteron by comparison of the theoretical and experimental spin averaged frequencies. We used the experiment-theory agreement to set an upper limit on a hypothetical spin-independent fifth force between proton and deuteron, with a factor of 21 improvement compared to previous bounds from MHI spectroscopy. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Experimentalphysik | |||||||
| Dokument erstellt am: | 02.06.2021 | |||||||
| Dateien geändert am: | 02.06.2021 | |||||||
| Promotionsantrag am: | 26.05.2020 | |||||||
| Datum der Promotion: | 14.10.2020 |
