Measurement of Ultralow Heating Rates of a Single Antiproton in a Cryogenic Penning Trap

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Measurement of Ultralow Heating Rates of a Single Antiproton in a Cryogenic Penning Trap

M. J. Borchert, P. E. Blessing, J. A. Devlin, J. A. Harrington, T. Higuchi, J. Morgner, C. Smorra, E. Wursten, M. Bohman, M. Wiesinger, A. Mooser, K. Blaum, Y. Matsuda, C. Ospelkaus, W. Quint, J. Walz, Y. Yamazaki, and S. Ulmer

Phys. Rev. Lett. 122, 043201 – Published 28 January 2019

Abstract

We report on the first detailed study of motional heating in a cryogenic Penning trap using a single antiproton. Employing the continuous Stern-Gerlach effect we observe cyclotron quantum transition rates of $6 (1) quanta / h$ and an electric-field noise spectral density below $7.5 (3.4) \times 10^{- 20} V^{2} m^{- 2} {Hz}^{- 1}$ , which corresponds to a scaled noise spectral density below $8.8 (4.0) \times 10^{- 12} V^{2} m^{- 2}$ , results which are more than 2 orders of magnitude smaller than those reported by other ion-trap experiments.

Received 31 October 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.043201

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Penning traps

Exotic baryons Trapped ions

Angular momentum CPT symmetry

Atom & ion cooling Precision measurements Spectroscopy

Atomic, Molecular & OpticalAccelerators & BeamsParticles & FieldsQuantum Information, Science & Technology

Authors & Affiliations

M. J. Borchert^1,2,*, P. E. Blessing^1,3, J. A. Devlin¹, J. A. Harrington^1,4, T. Higuchi^1,5, J. Morgner^1,2, C. Smorra¹, E. Wursten^1,7, M. Bohman^1,4, M. Wiesinger^1,4, A. Mooser¹, K. Blaum⁴, Y. Matsuda⁵, C. Ospelkaus^2,8, W. Quint^3,9, J. Walz^6,10, Y. Yamazaki¹¹, and S. Ulmer¹

¹RIKEN, Ulmer Fundamental Symmetries Laboratory, Wako, Saitama 351-0198, Japan
²Institut für Quantenoptik, Leibniz Universität Hannover, 30167 Hannover, Germany
³GSI-Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
⁴Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
⁵Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan
⁶Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
⁷CERN, 1211 Geneva 23, Switzerland
⁸Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
⁹Ruprecht-Karls-Universität Heidelberg, 69047 Heidelberg, Germany
¹⁰Helmholtz-Institut Mainz, 55099 Mainz, Germany
¹¹Atomic Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan

^*matthias.joachim.borchert@cern.ch

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Vol. 122, Iss. 4 — 1 February 2019

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Figure 1
Experimental setup. The particle is confined inside a set of five cylindrical electrodes (golden/brown) with an inner diameter of 3.6 mm. The central ring electrode is made out of a cobalt-iron alloy generating the magnetic inhomogeneity used for application of the continuous Stern-Gerlach effect [20]. An ultrastable voltage source (UM 1-14 by Stahl electronics) is connected to the trap electrodes via multistage low-pass filters. The central electrode voltage is simultaneously recorded by a FLUKE F8505A reference voltmeter. For axial frequency measurements, a feedback-cooled (a) image current detection system (blue) is used, which is connected to an outer electrode [23]. The particles’ axial oscillation frequency is obtained from the fast Fourier transformed detector spectrum (b). A Rohde&Schwarz SMB 100A frequency generator equipped with high order low-pass and band-pass filters is used for particle manipulation (c).
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Figure 2
Axial frequency stability analysis for an antiproton at low radial energy. The differential Allan deviation $σ_{ν_{z}} (τ)$ is displayed in blue. Frequency measurement noise (FFT, dark red squares) and voltage fluctuations (dark red triangles) contribute to the observed frequency instability. Contributions from a simulated random walk of the cyclotron energy are displayed in orange. The dashed black line is given by the sum of random walk, FFT, and voltage contributions. For time spans larger than 250 s, the Allan deviation is dominated by random walks, $ζ_{+} = 6 (1) h^{- 1}$ . Transition rate uncertainties are extracted from the $σ_{ν_{z}} (τ)$ -error bars. For this data set, 900 frequency measurements were conducted over 12 h.
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Figure 3
Single particle stabilities as a function of the electrode-to-ion distance $d$ . Figure (a) displays the electric-field noise spectral density $S_{E} (ω)$ scaled by angular trap frequency $ω$ , Fig. (b) depicts heating rates $d \bar{n} / d t$ , and in Fig. (c) the energy increase $d E / d t$ is shown. The triangles represent measurements performed in cryogenic 2D-Paul traps [32, 33, 34, 35, 36, 37, 38]; squares denote measurements in Penning traps on single ions [21] and ion crystals [39, 40] conducted at room temperature. This work is plotted as a blue circle.
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Figure 4
Results of frequency stability measurements for particles at different magnetron radii $ρ_{-}$ . (a) Measured Allan deviation $σ_{ν_{z}} (τ)$ of the axial frequency for an averaging time of $τ = 250 s$ . The black line denotes calculated values for $σ_{ν_{z}} (τ)$ assuming transition rates are linked to trap voltage fluctuations. (b) Calculated electrode voltage fluctuations $S_{V}$ . The linear increase of $σ_{ν_{z}} (τ)$ is in good agreement with cyclotron transition rates driven by trapping voltage fluctuations. The extracted voltage fluctuation $S_{V} (ω_{+})$ (black lines) is constant for $6 μ m \leq ρ_{-} \leq 65 μ m$ , confirming that they can be regarded as the dominant source of electric-field fluctuations in the trap.
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