Observation of Spin Flips with a Single Trapped Proton

Ulmer, S.; Rodegheri, Cricia C.; Blaum, Klaus; Kracke, Holger; Mooser, A.; Quint, W.; Walz, J.

doi:10.1103/physrevlett.106.253001

Cited by 82 publications

(93 citation statements)

References 18 publications

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“…changes in ν z,AT is the major challenge in measuring the antiproton magnetic moment. Only antiprotons with a cyclotron energy E + /k B below the threshold energy frequency fluctuations that are sufficiently small to clearly resolve single antiproton spin transitions 23,24 (Fig. 1c).…”

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confidence: 99%

A parts-per-billion measurement of the antiproton magnetic moment

Smorra

Sellner²,

Borchert

et al. 2017

Nature

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Precise comparisons of the fundamental properties of matterantimatter conjugates provide sensitive tests of charge-parity-time (CPT) invariance 1 , which is an important symmetry that rests on basic assumptions of the standard model of particle physics. Experiments on mesons 2 , leptons 3,4 and baryons 5,6 have compared different properties of matter-antimatter conjugates with fractional uncertainties at the parts-per-billion level or better. One specific quantity, however, has so far only been known to a fractional uncertainty at the parts-per-million level 7,8 : the magnetic moment of the antiproton, μ p . The extraordinary difficulty in measuring μ p with high precision is caused by its intrinsic smallness; for example, it is 660 times smaller than the magnetic moment of the positron 3 . Here we report a high-precision measurement of μ p in units of the nuclear magneton μ N with a fractional precision of 1.5 parts per billion (68% confidence level). We use a two-particle spectroscopy method in an advanced cryogenic multi-Penning trap system. Our result μ p = −2.7928473441(42)μ N (where the number in parentheses represents the 68% confidence interval on the last digits of the value) improves the precision of the previous best μ p measurement 8 by a factor of approximately 350. The measured value is consistent with the proton magnetic moment 9 , μ p = 2.792847350(9)μ N , and is in agreement with CPT invariance. Consequently, this measurement constrains the magnitude of certain CPT-violating effects 10 to below 1.8 × 10 −24 gigaelectronvolts, and a possible splitting of the protonantiproton magnetic moments by CPT-odd dimension-five interactions to below 6 × 10 −12 Bohr magnetons 11 .Within the physics programme at the Antiproton Decelerator of CERN, the properties of protons and antiprotons 5,6 , antiprotons and electrons 12 , and hydrogen 13 and antihydrogen 14,15 are compared with high precision. Such experiments, including those described here, provide stringent tests of CPT invariance. Our presented antiproton magnetic moment measurement reaches a fractional precision of 1.5 parts per billion (p.p.b.) at 68% confidence level, enabled by our new measurement scheme. Compared to the double-Penning trap technique 16 used in the measurement of the proton magnetic moment 9 , this new method eliminates the need for cyclotron cooling in each measurement cycle and increases the sampling rate.Our technique uses a hot cyclotron antiproton for measurements of the cyclotron frequency ν c , and a cold Larmor antiproton to determine the Larmor frequency ν L . By evaluating the ratio of the frequencies measured in the same magnetic field, the magnetic moment of the antiproton (in units of the nuclear magneton, the g-factor) ν ν μ μN is obtained. With this new technique we have improved the precision of the previous best antiproton magnetic moment measurement 8 by a factor of approximately 350 (Fig. 1a).Our experiment 17 is located in the Antiproton Decelerator facility, which provides bunches of 30 million antiprotons at a...

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confidence: 99%

A parts-per-billion measurement of the antiproton magnetic moment

Smorra

Sellner²,

Borchert

et al. 2017

Nature

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130

145

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“…6 to determine R in =8.5(5) MΩ. A more detailed discussion of the amplifiers which are used in our experiment is described in reference [20].…”

Section: Amplifiermentioning

confidence: 99%

“…We use custom-made cryogenic amplifiers based on Dual-gate GaAs MES-FET to amplify the particle signals [20]. They consist of a common-source circuit at the input and a source-follower circuit at the output.…”

Section: Amplifiermentioning

confidence: 99%

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Highly sensitive superconducting circuits at ∼700 kHz with tunable quality factors for image-current detection of single trapped antiprotons

Nagahama

Schneider

Mooser

et al. 2016

Review of Scientific Instruments

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We developed highly-sensitive image-current detection systems based on superconducting toroidal coils and ultra-low noise amplifiers for non-destructive measurements of the axial frequencies (550∼800 kHz) of single antiprotons stored in a cryogenic multi-Penning-trap system. The unloaded superconducting tuned circuits show quality factors of up to 500 000, which corresponds to a factor of 10 improvement compared to our previously used solenoidal designs. Connected to ultra-low noise amplifiers and the trap system, signal-to-noise-ratios of 30 dB at quality factors of > 20 000 are achieved. In addition, we have developed a superconducting switch which allows continuous tuning of the detector's quality factor, and to sensitively tune the particle-detector interaction. This allowed us to improve frequency resolution at constant averaging time, which is crucial for single antiproton spin-transition spectroscopy experiments, as well as improved measurements of the proton-to-antiproton charge-to-mass ratio.

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“…A challenging example of Penning trap precision measurements are single protons and antiprotons. Comparisons of the g-factor and q/m of single protons and antiprotons for testing the fundamental CPT symmetry have progressed rapidly [1][2][3][4][5][6][7]. These experiments employ IIC and the continuous Stern-Gerlach effect [8] for spin state detection and suffer from the difficulty to cool the particles efficiently below 4 K [2].…”

Section: Introductionmentioning

confidence: 99%