Improved bounds on Lorentz violation from composite pulse Ramsey spectroscopy in a trapped ion

Abstract

In attempts to unify the four known fundamental forces in a single quantum-consistent theory, it is suggested that Lorentz symmetry may be broken at the Planck scale. Here we search for Lorentz violation at the low-energy limit by comparing orthogonally oriented atomic orbitals in a Michelson-Morley-type experiment. We apply a robust radiofrequency composite pulse sequence in the 2F7/2 manifold of an Yb+ ion, extending the coherence time from 200 μs to more than 1 s. In this manner, we fully exploit the high intrinsic susceptibility of the 2F7/2 state and take advantage of its exceptionally long lifetime. We match the stability of the previous best Lorentz symmetry test nearly an order of magnitude faster and improve the constraints on the symmetry breaking coefficients to the 10−21 level. These results represent the most stringent test of this type of Lorentz violation. The demonstrated method can be further extended to ion Coulomb crystals.

Excitation of Forbidden Electronic Transitions in Atoms by Hermite–Gaussian Modes

“…This 467 nm transition, proceeding via the E3 channel, is of great interest since it serves as the reference for high‐precision optical clocks and enables searches for new physics. [ 27–29 ] Below we shall focus our attention on the transition between the magnetic sublevels $$M_\text{g} = M_\text{e} = 0$$ that can be spectroscopically resolved by the Zeeman effect. As seen from Equation (5), the evaluation of the transition amplitudes requires knowledge of the reduced matrix element $$\langle 4\text{f}^{13} 6\text{s}^2 \, ^2F_{7/2} || H_{\gamma } (E3) || 4\text{f}^{14} 6\text{s} \, ^2S_{1/2} \rangle$$.…”

Robust and scalable rf spectroscopy in first-order magnetic sensitive states at second-long coherence time

“…κ = κ QS + κ LV . A signal for a possible Lorentz violation is encoded in small temporal modulations of κ LV at harmonics of Earth's rotation frequency and its harmonics [18,24].…”

“…An example of useful implementation of the UR10 sequence is for a test of LLI that is based on a search for a m 2 J -dependent energy shift between the sublevels in the 2 F 7/2 manifold that oscillates at frequencies related to Earth's rotation [18,24]. Such an energy shift is transferred via the UR10 composite pulse Ramsey sequence into modulations in the retrieved population in the |F, −1/2⟩ state after the final rf Ramsey π/2-pulse.…”

“…In this work we apply rf composite pulse Ramsey sequences based on the universal rotation (UR) method with 10 rephasing pulses (UR10) [19] for precision metrology in the meta-stable 2 F 7/2 manifold of a trapped 172 Yb + ion. We demonstrate that the UR10 sequence is more robust than the less complex GSE method and implemented it in a trapped ion for the first time to test LLI [24]. We compare the two rf sequences both theoretically and experimentally in the more simple spin-1/2 2 S 1/2 electronic ground state of 172 Yb + and show that the UR10 approach is 38 (13) times less sensitive to pulse duration (frequency detuning) errors than the GSE sequence.…”

“…We apply the UR10 sequence in the 2 F 7/2 state and demonstrate a coherent signal of up to 2.5 s with 10 4 rephasing pulses. This sequence has enabled the most stringent test of Lorentz symmetry in the electron-photon sector to date, in which all the sublevels of the 2 F 7/2 manifold were used, including the most sensitive m J = ±7/2 substates as presented in [24]. The method is also suitable for accurate measurements of QSs to determine the quadrupole moments of meta-stable quantum states [25].…”