Project B06: Quantum metrology with trapped (anti-)protons

Frequency measurements on single trapped (anti-)protons allow sensitive tests of the fundamental CPT symmetry. Present efforts within the BASE collaboration progress at a rapid pace, but are extremely challenging because of the difficulty of achieving sufficiently low temperatures of the particles. The aim of this project is to advance precision measurements with single (anti-)protons through sympathetic laser cooling and detection with a laser-cooled atomic ion.

Introduction

We aim to apply laser-based quantum logic techniques developed in the context of ion-trap quantum computing for cooling and readout of single (anti-)protons. The quantum logic approach relies on manipulating and detecting the (anti-)proton indirectly through a co-trapped atomic “logic” ion (Be+ in our case). This allows for ground state cooling of (anti-)protons, with a corresponding gain of more than 3 orders of magnitude in terms of particle localisation and a much faster readout speed (by two to three orders of magnitude). Both will be highly beneficial in the identification, characterisation and suppression of systematic effects and in achieving lower statistical uncertainties. The system offers the intriguing possibility of using the “logic” ion as a flywheel for the magnetic field stabilisation in a g-factor comparison. This project contributes directly to the DQ-mat core goals of composing quantum systems, enhancing quantum sensors & metrology and testing fundamental physics.

Results

We have built and commissioned a cryogenic 5 T superconducting magnet Penning trap system, loaded single Be+ ions and demonstrated laser cooling and mode coupling. We have proposed a method for elementary quantum logic gates on (anti-)protons in Penning traps and, based on this, an implementation of quantum logic spectroscopy (QLS) of (anti-)protons to test CPT symmetry. We have analyzed the implications for constraining Standard Model Extension (SME) coefficients and CPT tests. A key milestone for the implementation of these methods was to demonstrate two complementary methods for stimulated-Raman optical control of ions using a UV femtosecond frequency comb and 140 GHz offset phase-locked CW UV lasers. Using the latter, we have implemented single-ion resolved-sideband spectroscopy, which has culminated in the demonstration of single-ion ground state cooling, one of only two experiments worldwide to achieve this essential prerequisite for the implementation of quantum logic spectroscopy.

We were also able to demonstrate, for the first time in Penning traps, another key prerequisite – fast adiabatic transport without a detectable energy increase, which is required to connect trap zones of different functionality for QLS. Ongoing experiments explore Coulomb coupling of Be+ ions in a double-well potential so that, in a second step, the required (anti-)proton– Be+ coupling for sympathetic cooling and QLS can be demonstrated.

We have contributed to a series of ground-breaking measurements of the BASE (Baryon-Antibaryon Symmetry Experiment) collaboration on antiproton g-factor measurements and CPT symmetry tests. The BASE measurements have placed limits on potential interactions between axion-like dark matter on the one hand and antimatter and photons on the other hand. We have collaborated with BASE-Mainz on the demonstration of a complementary resonator-based sympathetic laser cooling technique with protons.


Publications

Showing results 1 - 4 out of 4

Mielke J, Pick J, Coenders J-A, Meiners T, Niemann M, Cornejo JM et al. 139 GHz UV phase-locked Raman laser system for thermometry and sideband cooling of 9Be+ ions in a Penning trap. Journal of Physics B: Atomic, Molecular and Optical Physics. 2021 Nov 15;54(19):195402. doi: 10.1088/1361-6455/ac319d
Nitzschke D, Schulte M, Niemann M, Cornejo JM, Ulmer S, Lehnert R et al. Elementary laser‐less quantum logic operations with (anti‐)protons in penning traps. Advanced Quantum Technologies. 2020 Jun 16;3(11):1900133. doi: 10.1002/qute.201900133
Paschke A-G, Zarantonello G, Hahn H, Lang T, Manzoni C, Marangoni M et al. Versatile Control of Be+ 9 Ions Using a Spectrally Tailored UV Frequency Comb. Physical Review Letters. 2019 Mar 29;122(12):123606. doi: 10.48550/arXiv.1903.02965, 10.1103/PhysRevLett.122.123606
Meiners T, Niemann M, Mielke J, Borchert M, Pulido N, Cornejo JM et al. Towards sympathetic cooling of single (anti-)protons. Hyperfine Interactions. 2018 Dec 1;239(1):26. doi: 10.1007/s10751-018-1502-6
All publications of the Collaborative Research Centre

Project leader

Prof. Dr. Christian Ospelkaus
Executive Board
Address
Welfengarten 1
30167 Hannover
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Welfengarten 1
30167 Hannover
Building
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Dr. Juan Manuel Cornejo-Garcia
Address
Welfengarten 1
30167 Hannover
Dr. Juan Manuel Cornejo-Garcia
Address
Welfengarten 1
30167 Hannover

Staff

Jan Schaper
Address
Welfengarten 1
30167 Hannover
Jan Schaper
Address
Welfengarten 1
30167 Hannover
Julia-Aileen Coenders
Address
Welfengarten 1
30167 Hannover
Julia-Aileen Coenders
Address
Welfengarten 1
30167 Hannover