Unpolarized, incoherent repumping light for prevention of dark states in a trapped and laser-cooled single ion

T. Lindvall, T. Fordell, I. Tittonen, M. Merimaa

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)

Abstract

Many ion species commonly used for laser-cooled ion-trapping studies have a low-lying metastable 2D3/2 state that can become populated due to spontaneous  emission from the 2P1/2 excited state. This requires a repumper laser to maintain the ion in the Doppler cooling cycle. Typically, the 2D3/2 state, or some of its hyperfine components if the ion has nuclear spin, has a higher multiplicity than the upper state of the repumping transition. This can lead to dark states, which have to be destabilized by an external magnetic field or by modulating the polarization of the repumper laser. We propose using unpolarized, incoherent amplified spontaneous emission (ASE) to drive the repumping transition. An ASE source offers several advantages compared to a laser. It prevents the buildup of dark states without external polarization modulation even in zero magnetic field, it can drive multiple hyperfine transitions simultaneously, and it requires no frequency stabilization. These features make it very compact and robust, which is essential for the development of practical, transportable optical ion clocks. We construct a theoretical model for the ASE radiation, including the possibility of the source being partially polarized. Using 88Sr+ as an example, the performance of the ASE source compared to a single-mode laser is analyzed by numerically solving the eight-level density-matrix equations for the involved energy levels. Finally, a reduced three-level system is derived, yielding a simple formula for the excited-state population and scattering rate, which can be used to optimize the experimental parameters. The required ASE power spectral density can be obtained with current technology.
Original languageEnglish
Article number013439
JournalPhysical Review A: Atomic, Molecular, and Optical Physics
Volume87
Issue number1
DOIs
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed

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spontaneous emission
lasers
ions
polarization modulation
laser modes
magnetic fields
nuclear spin
clocks
excitation
stabilization
energy levels
trapping
cooling
cycles
polarization
radiation
scattering

Cite this

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title = "Unpolarized, incoherent repumping light for prevention of dark states in a trapped and laser-cooled single ion",
abstract = "Many ion species commonly used for laser-cooled ion-trapping studies have a low-lying metastable 2D3/2 state that can become populated due to spontaneous  emission from the 2P1/2 excited state. This requires a repumper laser to maintain the ion in the Doppler cooling cycle. Typically, the 2D3/2 state, or some of its hyperfine components if the ion has nuclear spin, has a higher multiplicity than the upper state of the repumping transition. This can lead to dark states, which have to be destabilized by an external magnetic field or by modulating the polarization of the repumper laser. We propose using unpolarized, incoherent amplified spontaneous emission (ASE) to drive the repumping transition. An ASE source offers several advantages compared to a laser. It prevents the buildup of dark states without external polarization modulation even in zero magnetic field, it can drive multiple hyperfine transitions simultaneously, and it requires no frequency stabilization. These features make it very compact and robust, which is essential for the development of practical, transportable optical ion clocks. We construct a theoretical model for the ASE radiation, including the possibility of the source being partially polarized. Using 88Sr+ as an example, the performance of the ASE source compared to a single-mode laser is analyzed by numerically solving the eight-level density-matrix equations for the involved energy levels. Finally, a reduced three-level system is derived, yielding a simple formula for the excited-state population and scattering rate, which can be used to optimize the experimental parameters. The required ASE power spectral density can be obtained with current technology.",
author = "T. Lindvall and T. Fordell and I. Tittonen and M. Merimaa",
year = "2013",
doi = "10.1103/PhysRevA.87.013439",
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Unpolarized, incoherent repumping light for prevention of dark states in a trapped and laser-cooled single ion. / Lindvall, T.; Fordell, T.; Tittonen, I.; Merimaa, M.

In: Physical Review A: Atomic, Molecular, and Optical Physics, Vol. 87, No. 1, 013439, 2013.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Unpolarized, incoherent repumping light for prevention of dark states in a trapped and laser-cooled single ion

AU - Lindvall, T.

AU - Fordell, T.

AU - Tittonen, I.

AU - Merimaa, M.

PY - 2013

Y1 - 2013

N2 - Many ion species commonly used for laser-cooled ion-trapping studies have a low-lying metastable 2D3/2 state that can become populated due to spontaneous  emission from the 2P1/2 excited state. This requires a repumper laser to maintain the ion in the Doppler cooling cycle. Typically, the 2D3/2 state, or some of its hyperfine components if the ion has nuclear spin, has a higher multiplicity than the upper state of the repumping transition. This can lead to dark states, which have to be destabilized by an external magnetic field or by modulating the polarization of the repumper laser. We propose using unpolarized, incoherent amplified spontaneous emission (ASE) to drive the repumping transition. An ASE source offers several advantages compared to a laser. It prevents the buildup of dark states without external polarization modulation even in zero magnetic field, it can drive multiple hyperfine transitions simultaneously, and it requires no frequency stabilization. These features make it very compact and robust, which is essential for the development of practical, transportable optical ion clocks. We construct a theoretical model for the ASE radiation, including the possibility of the source being partially polarized. Using 88Sr+ as an example, the performance of the ASE source compared to a single-mode laser is analyzed by numerically solving the eight-level density-matrix equations for the involved energy levels. Finally, a reduced three-level system is derived, yielding a simple formula for the excited-state population and scattering rate, which can be used to optimize the experimental parameters. The required ASE power spectral density can be obtained with current technology.

AB - Many ion species commonly used for laser-cooled ion-trapping studies have a low-lying metastable 2D3/2 state that can become populated due to spontaneous  emission from the 2P1/2 excited state. This requires a repumper laser to maintain the ion in the Doppler cooling cycle. Typically, the 2D3/2 state, or some of its hyperfine components if the ion has nuclear spin, has a higher multiplicity than the upper state of the repumping transition. This can lead to dark states, which have to be destabilized by an external magnetic field or by modulating the polarization of the repumper laser. We propose using unpolarized, incoherent amplified spontaneous emission (ASE) to drive the repumping transition. An ASE source offers several advantages compared to a laser. It prevents the buildup of dark states without external polarization modulation even in zero magnetic field, it can drive multiple hyperfine transitions simultaneously, and it requires no frequency stabilization. These features make it very compact and robust, which is essential for the development of practical, transportable optical ion clocks. We construct a theoretical model for the ASE radiation, including the possibility of the source being partially polarized. Using 88Sr+ as an example, the performance of the ASE source compared to a single-mode laser is analyzed by numerically solving the eight-level density-matrix equations for the involved energy levels. Finally, a reduced three-level system is derived, yielding a simple formula for the excited-state population and scattering rate, which can be used to optimize the experimental parameters. The required ASE power spectral density can be obtained with current technology.

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