Trapped-ion quantum sensors have become highly sensitive tools for the search of physics beyond the Standard Model. Recently, stringent tests of local Lorentz-invariance (LLI) have been conducted with precision spectroscopy in trapped ions (Pruttivarasin et al 2015 Nature 517 592-5, Megidish et al 2019 Phys. Rev. Lett. 122 123605, Sanner et al 2019 Nature 567 204-8, Dreissen et al 2022 Nat. Commun. 13 1-6) . We here elaborate on robust radio-frequency composite-pulse spectroscopy at second long coherence times in the magnetic sublevels of the long-lived 2F7/2 state of a trapped 172Yb+ ion which is scalable to spatially extended multi-ion systems. We compare two Ramsey-type composite rf pulse sequences, a generalized spin-echo (GSE) sequence (Shaniv et al 2018 Phys. Rev. Lett. 120 103202) and a sequence based on universal rotations with 10 rephasing pulses (UR10) (Genov et al 2017 Phys. Rev. Lett. 118 133202) that decouple the energy levels from magnetic field noise, enabling robust and accurate spectroscopy. Both sequences are characterized theoretically and experimentally in the spin- 1 / 22 S1/2 electronic ground state of 172Yb+ and results show that the UR10 sequence is 38 (13) times more robust against pulse duration (frequency detuning) errors than the GSE sequence. We extend our simulations to the eight-level manifold of the 2F7/2 state, which is highly sensitive to a possible violation of LLI, and show that the UR10 sequence can be used for high-fidelity Ramsey spectroscopy in noisy environments. The UR10 sequence is implemented experimentally in the 2F7/2 manifold and a coherent signal of up to 2.5 s is reached. In (Dreissen et al 2022 Nat. Commun. 13 1-6) we have implemented this sequence and used it to perform the most stringent test of LLI in the electron-photon sector to date with a single Yb+ ion. Due to the high robustness of the UR10 sequence, it can be applied on larger ion crystals to improve tests of Lorentz symmetry further. We demonstrate that the sequence can also be used to extract the quadrupole moment of the meta-stable 2F7/2 state, obtaining a value of Θ = - 0.0298 (38)ea02 which is in agreement with the value deduced from clock measurements (Lange et al 2020 Phys. Rev. Lett. 125 143201).
Trapped-ion quantum sensors have become highly sensitive tools for the search of physics beyond the Standard Model. Recently, stringent tests of local Lorentz-invariance (LLI) have been conducted with precision spectroscopy in trapped ions (Pruttivarasin et al 2015 Nature 517 592-5, Megidish et al 2019 Phys. Rev. Lett. 122 123605, Sanner et al 2019 Nature 567 204-8, Dreissen et al 2022 Nat. Commun. 13 1-6) . We here elaborate on robust radio-frequency composite-pulse spectroscopy at second long coherence times in the magnetic sublevels of the long-lived 2F7/2 state of a trapped 172Yb+ ion which is scalable to spatially extended multi-ion systems. We compare two Ramsey-type composite rf pulse sequences, a generalized spin-echo (GSE) sequence (Shaniv et al 2018 Phys. Rev. Lett. 120 103202) and a sequence based on universal rotations with 10 rephasing pulses (UR10) (Genov et al 2017 Phys. Rev. Lett. 118 133202) that decouple the energy levels from magnetic field noise, enabling robust and accurate spectroscopy. Both sequences are characterized theoretically and experimentally in the spin- 1 / 22 S1/2 electronic ground state of 172Yb+ and results show that the UR10 sequence is 38 (13) times more robust against pulse duration (frequency detuning) errors than the GSE sequence. We extend our simulations to the eight-level manifold of the 2F7/2 state, which is highly sensitive to a possible violation of LLI, and show that the UR10 sequence can be used for high-fidelity Ramsey spectroscopy in noisy environments. The UR10 sequence is implemented experimentally in the 2F7/2 manifold and a coherent signal of up to 2.5 s is reached. In (Dreissen et al 2022 Nat. Commun. 13 1-6) we have implemented this sequence and used it to perform the most stringent test of LLI in the electron-photon sector to date with a single Yb+ ion. Due to the high robustness of the UR10 sequence, it can be applied on larger ion crystals to improve tests of Lorentz symmetry further. We demonstrate that the sequence can also be used to extract the quadrupole moment of the meta-stable 2F7/2 state, obtaining a value of Θ = - 0.0298 (38)ea02 which is in agreement with the value deduced from clock measurements (Lange et al 2020 Phys. Rev. Lett. 125 143201).
Abstract Trapped-ion quantum sensors have become highly sensitive tools for the search of physics beyond the Standard Model. Recently, stringent tests of local Lorentz-invariance (LLI) have been conducted with precision spectroscopy in trapped ions (Pruttivarasin et al 2015 Nature 517 592–5, Megidish et al 2019 Phys. Rev. Lett. 122 123605, Sanner et al 2019 Nature 567 204–8, Dreissen et al 2022 Nat. Commun. 13 1–6) . We here elaborate on robust radio-frequency composite-pulse spectroscopy at second long coherence times in the magnetic sublevels of the long-lived 2 F 7 / 2 state of a trapped 172Yb+ ion which is scalable to spatially extended multi-ion systems. We compare two Ramsey-type composite rf pulse sequences, a generalized spin-echo (GSE) sequence (Shaniv et al 2018 Phys. Rev. Lett. 120 103202) and a sequence based on universal rotations with 10 rephasing pulses (UR10) (Genov et al 2017 Phys. Rev. Lett. 118 133202) that decouple the energy levels from magnetic field noise, enabling robust and accurate spectroscopy. Both sequences are characterized theoretically and experimentally in the spin- 1 / 2 2 S 1 / 2 electronic ground state of 172Yb+ and results show that the UR10 sequence is 38 (13) times more robust against pulse duration (frequency detuning) errors than the GSE sequence. We extend our simulations to the eight-level manifold of the 2 F 7 / 2 state, which is highly sensitive to a possible violation of LLI, and show that the UR10 sequence can be used for high-fidelity Ramsey spectroscopy in noisy environments. The UR10 sequence is implemented experimentally in the 2 F 7 / 2 manifold and a coherent signal of up to 2.5 s is reached. In (Dreissen et al 2022 Nat. Commun. 13 1–6) we have implemented this sequence and used it to perform the most stringent test of LLI in the electron–photon sector to date with a single Yb+ ion. Due to the high robustness of the UR10 sequence, it can be applied on larger ion crystals to improve tests of Lorentz symmetry further. We demonstrate that the sequence can also be used to extract the quadrupole moment of the meta-stable 2 F 7 / 2 state, obtaining a value of Θ = − 0.0298 ( 38 ) e a 0 2 which is in agreement with the value deduced from clock measurements (Lange et al 2020 Phys. Rev. Lett. 125 143201).
Trapped-ion quantum sensors have become highly sensitive tools for the search of physics beyond the Standard Model. Recently, stringent tests of local Lorentz-invariance (LLI) have been conducted with precision spectroscopy in trapped ions. We here elaborate on robust radio-frequency composite-pulse spectroscopy at second long coherence times in the magnetic sublevels of the long-lived 2F7/2 state of a trapped 172Yb+ ion which is scalable to spatially extended multi-ion systems. We compare two Ramsey-type composite rf pulse sequences, a GSE sequence and a UR10 that decouple the energy levels from magnetic field noise, enabling robust and accurate spectroscopy. Both sequences are characterized theoretically and experimentally in the spin-1/2\ 2S1/2 electronic ground state of 172Yb+ and results show that the UR10 sequence is 38 (13) times more robust against pulse duration (frequency detuning) errors than the GSE sequence. We extend our simulations to the eight-level manifold of the 2F7/2 state, which is highly sensitive to a possible violation of LLI, and show that the UR10 sequence can be used for high-fidelity Ramsey spectroscopy in noisy environments. The UR10 sequence is implemented experimentally in the 2F7/2 manifold and a coherent signal of up to 2.5\,s is reached. In reference we have implemented this sequence and used it to perform the most stringent test of LLI in the electron-photon sector to date with a single Yb+ ion. Due to the high robustness of the UR10 sequence, it can be applied on larger ion crystals to improve tests of Lorentz symmetry further. We demonstrate that the sequence can also be used to extract the quadrupole moment of the meta-stable 2F7/2 state, obtaining a value of Θ=−0.0298(38)ea02 which is in agreement with the value deduced from clock measurements.
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 2 F 7/2 manifold of an Yb + ion, extending the coherence time from 200 μ s to more than 1 s. In this manner, we fully exploit the high intrinsic susceptibility of the 2 F 7/2 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.
We develop a theory of composite Ramsey sequences of rf pulses interacting with the Zeeman structure at the long-lived atomic level, beyond the rotating wave approximation. Such sequences are proposed in experiments to detect the violation of local Lorentz invariance [R. Shaniv, R. Ozeri, M.S. Safronova, S.G. Porsev, V.A. Dzuba, V.V. Flambaum, and H. Häffner, Phys. Rev. Lett. 120, 103202 (2018)]. Based on Fourier analysis, we have shown that taking into account non-resonant contributions leads to a radical change in the dynamics of the quantum system (with respect to the rotating wave approximation) in the case when the number of Ramsey pulses exceeds several tens. As a result, the effectiveness of using such rf pulses sequences to test local Lorentz invariance has not yet been fully determined and requires additional research.
Quantum magnetometry represents a fundamental component of quantum metrology, where trapped-ion systems have achieved pT/Hz sensitivity in single-ion radio-frequency magnetic field measurements via dressed states based dynamical decoupling. Here we propose a scalable trapped-ion magnetometer utilizing the mixed dynamical decoupling method, combining dressed states with periodic sequences to suppress decoherence and spatial magnetic field inhomogeneity. With numerical simulations for a 104 ion system with realistic experimental parameters, we demonstrate that a sensitivity of 13 fT/Hz for the radio-frequency field could be reached. Such a sensitivity could be obtained via robust resilience to magnetic field drift noise and inhomogeneity, where coherence time could be extended to the order of several minutes on average. This method enables scalable trapped-ion magnetometry, demonstrating its potential as a robust and practical solution for advancing quantum sensing applications.
This thesis describes an ion trap magnetometer, in which experimental hardware and theory for trapped ion magnetometry has been developed and demonstrated. Quantum magnetometry has been a fast expanding field in recent years due to the plethora of military, medical and security applications. The current quantum magnetometer literature has shown great improvements on the standard magnetometer success metrics such as sensitivity, spacial resolution, frequency tuneability, noise shielding and vector field resolution. Ion trap magnetometry could potentially boast several advantages over some of the better established methods such as, nano-meter spatial resolution, broadband tuneability over radio-frequency (RF) and microwave frequencies, and magnetic field noise shielding and sensitivity improvements through dynamic decoupling methods; all in room temperature environments. The experimental setup discussed uses a micro-fabricated Paul trap for ion confinement due to the scalability of this technology. The method for sensing that was demonstrated utilises long-wavelength radiation dressed states to extend the coherence time of a single 171Yb+ ion beyond the bare states and to allow for a high level of frequency tuneability. The coherence times measured were T2 = 0:645 s for RF field sensing at 15.616 MHz and T2 = 1.153 s for microwave field sensing at 12.658466 GHz. Sensitivities of SB = 125.857 ± 26.155 pT/ vHz for RF magnetic fields and SB = 102.054 ± 11.046 pT/ vHz for microwave magnetic fields were achieved experimentally. A novel micro-fabricated Paul trap for trapping multiple ion clusters was developed to improve sensitivity values by increasing the total number of trapped ions. The design confines ions over a two-dimensional surface spanning 0.65 x 1.00 mm which would also allow for magnetic field gradient measurements. Efforts have been made to miniaturise certain experimental hardware to further the development of portable trapped ion experiments. For this, a miniaturised RF resonator that could be used for radial confinement of ions within Paul traps has been developed. At the current stage of development it is capable of applying a peak RF voltage of 114.9 V with a Q value of 70 at a resonant frequency of O/2p = 12.65 MHz.