Optimal suppression of anharmonicity in Paul traps for laser-free single spin measurements

Paul traps allow for the confinement of charged particles in a vacuum, playing a crucial role in metrology applications such as standard frequency measurements and mass spectrometry. Single spin measurements of trapped atomic and molecular ions also provide valuable insights into their structural properties. Recent research has unveiled the feasibility of single-spin measurements of electrons, even in the absence of closed optical transitions [1]. This is achieved by transferring the spin information to the electron’s oscillation phase with a linear gradient magnetic field drive. However, the anharmonicity in the trap potential induces dephasing, degrading the precision of single spin measurements. Therefore, suppression of anharmonicity through static electric field compensation is of great importance. This research addresses the challenge of suppression of anharmonicity in Paul traps, complicated by the nonlinear dynamics of trapped ions governed by the nonlinear Mathieu equation. Employing the alternating frequency/time domain harmonic balance (AFT-HB) method, a semi-analytical approach, we investigated these dynamics and identified optimal conditions for anharmonicity suppression in Paul traps. Our findings demonstrate the feasibility of anharmonicity suppression under specific conditions and with tailored electrode geometries. This advancement paves the way for spin resonance spectroscopy in Paul traps with arbitrary ions.

[1] Phys. Rev. A 95, 012312 (2017).