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

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)×10 −20 V 2 m −2 Hz −1 , which corresponds to a scaled noise spectral density below 8.8(4.0) × 10 −12 V 2 m −2 , results which are more than two orders of magnitude smaller than those reported by other ion trap experiments.Quantum control techniques applied to trapped charged particles, well-isolated from environmental influences, have very versatile applications in metrology and quantum information processing. For example, elegant experiments on co-trapped laser cooled ions in Paul traps have provided highly precise state-of-the-art quantum logic clocks [1], enabled the development of exquisite atomic precision sensors [2] and the implementation of quantum information algorithms applied with highly entangled ion-crystals [3]. Decoherence effects from noise driven quantum transitions, commonly referred to as anomalous heating [4,5], affect the scalability of multiion systems, which would enable even more powerful algorithms. Trapped particles are also highly sensitive probes to test fundamental symmetries, and to search for physics beyond the standard model [6,7]. The most precise values of the mass of the electron [8] and the most stringent tests of bound-state quantum electrodynamics [9] are based on precise frequency measurements on highly-charged ions in Penning traps. Measurements of the properties of trapped electrons [10] and positrons [11] provide the most sensitive tests of quantum electrodynamics and of the fundamental charge-parity-time (CPT) invariance in the lepton sector [12,13]. Our experiments [14] make high-precision comparisons of the fundamental properties of protons and antiprotons, and provide stringent tests of CPT invariance in the baryon sector. We recently reported on an improved determination of the proton magnetic moment with a fractional precision of 300 parts in a trillion [16] and the * matthias.joachim.borchert@cern.ch first high-precision determination of the antiproton magnetic moment with a fractional precision of 1.5 parts in a billion [15]. This measurement, based on a newly invented multi-trap method, improves the fractional precision achieved in previous studies [17,18] by more than a factor of 3000. These multi-trap based high-precision magnetic moment measurements on protons and antiprotons require low-noise conditions much more demanding than in any other ion trap experiment. Compared to experiments on electrons and positrons [10,11], the 660fold smaller proton/antiproton magnetic moment makes it much more challenging to apply high-fidelity single particle spin-quantum spectroscopy techniques [19]. Our experiments become possible only in cryogenic ultra-lownoise Penning-trap instruments, which provide energy stabilities of the particle motion on the peV/s range, effectively corresponding to a para...

Sympathetic cooling of a trapped proton mediated by an LC circuit

“…We have previously performed higher precision temperature measurements using a dedicated, spatially distant trap with a ferromagnetic ring electrode that uses the shift of equation ( 25 ) to obtain a cyclotron energy resolution of up to 80 Hz K −1 (refs. 15 , 49 ) and have developed a similar trap to reach 10 mK temperature resolution in future cooling measurements.…”

Sympathetic cooling schemes for separately trapped ions coupled via image currents

“…The dip widths are defined by the trap size, the number of ions in the trap and the ion masses [29]. additional heating effects besides the one stemming from the resonator [51]. Fig.…”

“…In case of the common-endcap coupling, the heating by the resonator noise is strongly suppressed due to the resonator detuning of several hundred kHz. Additionally, other sources of heating are negligibly small [51]. We investigate the lower limit that can be achieved in the simulations by repeating the procedure for the cooling time constant, but initializing the proton at 1.5 mK, shown in Fig.…”

Millicharged dark matter detection with ion traps

“…By analyzing time sequences of axial frequency measurements ν z (t), the average radial quantum transition rates are obtained. With a highly optimized trap setup with which the antiproton magnetic moment was measured with 1.5 parts per billion precision, the BASE experiment at CERN reports on the observation of absolute cyclotron transition rates of 6(1) quanta per hour [44].…”