Lyman-α source for laser cooling antihydrogen

Gabrielse, Gerald; Głowacz, B.; Grzonka, D.; Hamley, Chris; Hessels, E. A.; Jones, Nathan B.; Khatri, G.; Lee, S. A.; Meisenhelder, Cole; Morrison, T P; Nottet, E.; Rasor, Cory; Ronald, Sam; Skinner, T. D. G.; Storry, C. H.; Tardiff, E. R.; Zambrano, Daniel; Zieliński, Marcin

doi:10.1364/ol.43.002905

Cited by 14 publications

(11 citation statements)

References 25 publications

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“…The pulsed THG scheme was chosen 28 over other alternatives 37 , 38 for its technical advantages, including the robustness in operation. A similar laser system has been reported by another group 39 . The 121.6-nm pulses were linearly polarized, and had a duration of 15 ns (full-width at half-maximum of laser intensity) at a 10-Hz repetition rate; hence the duty factor was 1.5 × 10 −7 .…”

Section: Methodssupporting

confidence: 57%

Laser cooling of antihydrogen atoms

Baker

Bertsche

Capra

et al. 2021

Nature

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The photon—the quantum excitation of the electromagnetic field—is massless but carries momentum. A photon can therefore exert a force on an object upon collision1. Slowing the translational motion of atoms and ions by application of such a force2,3, known as laser cooling, was first demonstrated 40 years ago4,5. It revolutionized atomic physics over the following decades6–8, and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen9, the antimatter atom consisting of an antiproton and a positron. By exciting the 1S–2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-α laser radiation10,11, we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude—with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S–2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic11–13 and gravitational14 studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules.

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Section: Methodssupporting

confidence: 57%

Laser cooling of antihydrogen atoms

Baker

Bertsche

Capra

et al. 2021

Nature

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“…Spectroscopy in the vacuum ultraviolet range is challenging even for ordinary atoms, owing in part to the lack of convenient laser sources and optical components [26][27][28] . Our pulsed, coherent 121.6-nm radiation was produced by generating the third harmonic of 365-nm pulses in a Kr/Ar gas mixture at a repetition rate of 10 Hz (ref.…”

Section: Investigation Of the Fine Structure Of Antihydrogenmentioning

confidence: 99%

Investigation of the fine structure of antihydrogen

Ahmadi¹,

Alves²,

Baker³

et al. 2020

Nature

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At the historic Shelter Island Conference on the Foundations of Quantum Mechanics in 1947, Willis Lamb reported an unexpected feature in the fine structure of atomic hydrogen: a separation of the 2S1/2 and 2P1/2 states1. The observation of this separation, now known as the Lamb shift, marked an important event in the evolution of modern physics, inspiring others to develop the theory of quantum electrodynamics2–5. Quantum electrodynamics also describes antimatter, but it has only recently become possible to synthesize and trap atomic antimatter to probe its structure. Mirroring the historical development of quantum atomic physics in the twentieth century, modern measurements on anti-atoms represent a unique approach for testing quantum electrodynamics and the foundational symmetries of the standard model. Here we report measurements of the fine structure in the n = 2 states of antihydrogen, the antimatter counterpart of the hydrogen atom. Using optical excitation of the 1S–2P Lyman-α transitions in antihydrogen6, we determine their frequencies in a magnetic field of 1 tesla to a precision of 16 parts per billion. Assuming the standard Zeeman and hyperfine interactions, we infer the zero-field fine-structure splitting (2P1/2–2P3/2) in antihydrogen. The resulting value is consistent with the predictions of quantum electrodynamics to a precision of 2 per cent. Using our previously measured value of the 1S–2S transition frequency6,7, we find that the classic Lamb shift in antihydrogen (2S1/2–2P1/2 splitting at zero field) is consistent with theory at a level of 11 per cent. Our observations represent an important step towards precision measurements of the fine structure and the Lamb shift in the antihydrogen spectrum as tests of the charge–parity–time symmetry8 and towards the determination of other fundamental quantities, such as the antiproton charge radius9,10, in this antimatter system.

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“…For the 121 nm we will use specifications that have been achieved in Ref. [56] of a laser energy of 190 nJ at a pulse duration of 16 ns, which results in a line width of δν L ≈ 27 MHz. For the other two lasers we will fix the pulse duration to typical 10 ns giving line widths of ≈44 MHz.…”

Section: A H − Excitation To Rydberg Hmentioning

confidence: 99%

Pulsed production of cold protonium in Penning traps

2019

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Precision comparison experiments on bound states of matter and antimatter rely on the production of corresponding systems at low temperatures and in sufficient numbers. In this paper we propose a scheme for the pulsed production of highly excited protonium (Pn) in a Penning-Malmberg trap at low kinetic energies of tens of meV. The scheme relies on the resonant-charge-exchange reaction H * +p → Pn * + e − where Rydberg excited hydrogen and antiprotons (p) interact to form Pn *. The reagent H(n = 30, l = 2) is created from laser photodetached and excited hydrogen anions (H −), which are initially trapped and mixed in a plasma together with electrons and antiprotons at low kinetic energies. We discuss a three-step pulsed laser excitation using rate equations. A semiclassical Monte Carlo approach leads to a formation rate of 10 5 Pn per 20 s when assuming a production temperature of 100 K. The formed Pn are internally excited in states with average principal quantum number n ≈ 1200 having lifetimes that can reach seconds. The proposed scheme is therefore particularly interesting for experiments aiming at the study of cold antimatter and purely baryonic systems for precision experiments (charge neutrality, gravity, spectroscopy), as performed at the antiproton decelerator facility at CERN.

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Lyman-α source for laser cooling antihydrogen

Cited by 14 publications

References 25 publications

Laser cooling of antihydrogen atoms

Laser cooling of antihydrogen atoms

Investigation of the fine structure of antihydrogen

Pulsed production of cold protonium in Penning traps

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