Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2606.02543

Suppression of differential light shifts in ground and metastable trapped-ion qubits

Drew Parks, Thomas Dellaert, Patrick McMillin, Conrad Roman, Andrei Derevianko, Wesley C. Campbell

Published Jun 1, 2026• 0 citations
arXivHTMLPDF

Abstract

In the presence of a magnetic field, hyperfine clock qubits can acquire a vector differential light shift that can be tuned via polarization to suppress the total differential light shift of high-power, off-resonant laser light. We experimentally measure this "magic" polarization condition, suppressing differential light shifts in both the ${}^2\mathrm{S}_{1/2}$ ground and ${}^2\mathrm{F}_{7/2}^o$ metastable clock qubits of $^{171}\mathrm{Yb}^+$. We present calculations of the minimum bias magnetic fields required to suppress differential light shifts in the ground state clock qubits of commonly trapped ion species, finding that they are below the strengths of fields already typically present in experiments. We further present methods for metastable clock-qubit control in $^{171}\mathrm{Yb}^+$, demonstrating a state preparation and measurement infidelity of $2.9^{+3.0}_{-1.5}\times10^{-4}$ ($-35 \pm 4 \, \mathrm{dB}$).

DOI
10.48550/arxiv.2606.02543

Related papers

Precision polarization tuning for light shift mitigation in trapped-ion qubits

Hengchao Tu, Chunyang Luan, Menglin Zou +3 more

Trapped-ion qubits are among the most promising candidates for quantum computing, quantum information processing, and quantum simulation. In general, trapped ions are considered to have sufficiently long coherence times, which are mainly characterized under laser-free conditions. However, in reality, essential laser fields for quantum manipulation introduce residual light shift, which seriously degrades the coherence due to power fluctuations. Here, we present a comprehensive study of ac Stark shifts in the hyperfine energy levels of the Yb + 171 ion, revealing an asymmetric light shift between two circular polarizations in the clock qubit and pronounced vector light shifts in the Zeeman qubits. By precisely tuning these polarizations, a remarkable enhancement in coherence time is observed, reaching over a 100-fold for the clock qubit and more than 10-fold for the Zeeman qubits, when comparing conditions of maximum and minimum shifts. These findings advance the practical realization of scalable trapped-ion quantum processors, enabling deep quantum circuit execution and long-duration adiabatic operations.

arXiv:2504.19474•Physical Review Research•Sep 3, 2025•4 citations

Compensation of Differential AC-Stark Shift in Trapped Ion Qubits via Auxiliary Laser Field

Z D Zhang, Wenbo Su, Yi Xie +5 more

Abstract Encoding qubit states in the ground states of zero nuclear spin trapped ions has the advantages of both long coherence time and simple energy structure. High-fidelity quantum operations on trapped-ion qubits are often hindered by the differential AC-Stark shift induced by state manipulation lasers. Here we propose and demonstrate a novel compensation approach that addresses this challenge without introducing additional laser sources or sacrificing the power of the manipulation lasers. Our method leverages an existing optical transition to induce a counteracting light shift on one of the qubit states. We experimentally validate this scheme using a single trapped 40 Ca + ion. We show that the differential AC-Stark shift induced by 393 nm Raman lasers on a ground-state Zeeman qubit can be compensated by a detuned 729 nm shelving laser. Conversely, we also demonstrate compensation of the shift induced by a 729 nm laser on a ground-to-metastable qubit using one of the 393 nm Raman beams. In both cases, the residual differential shift is suppressed by approximately two orders of magnitude compared to the uncompensated case. This method is universally applicable to various trapped-ion systems, offering a practical and power-effcient route to mitigate a key source of gate infidelity.

Chinese Physics B•Jun 22, 2026•0 citations

Controlling the magnetic-field sensitivity of atomic-clock states by microwave dressing

L. Sárkány, P. Weiss, H. Hattermann +1 more

We demonstrate control of the differential Zeeman shift between clock states of ultracold rubidium atoms by means of nonresonant microwave dressing. Using the dc field dependence of the microwave detuning, we suppress the first- and second-order differential Zeeman shift in magnetically trapped $^{87}\mathrm{Rb}$ atoms. By dressing the state pair $5{S}_{1/2}$ $F=1$, ${m}_{F}=\ensuremath{-}1$ and $F=2$, ${m}_{F}=1$, a residual frequency spread of $<0.1$ Hz in a range of 100 mG around a chosen magnetic offset field can be achieved. This is one order of magnitude smaller than the shift of the bare states at the magic field of the Breit-Rabi parabola. We further identify double magic points, around which the clock frequency is insensitive to fluctuations both in the magnetic field and in the dressing Rabi frequency. The technique is compatible with chip-based cold-atom systems and allows the creation of clock and qubit states with reduced sensitivity to magnetic-field noise.

arXiv:1410.8171•Physical Review A•Nov 13, 2014•53 citations

Magic polarization for cancellation of light shifts in two-photon optical clocks

Shira Jackson, Amar C. Vutha

We find a simple solution to the problem of probe laser light shifts in two-photon optical atomic clocks. We show that there exists a magic polarization at which the light shifts of the two atomic states involved in the clock transition are identical. We calculate the differential polarizability as a function of laser polarization for two-photon optical clocks based on neutral calcium and strontium, estimate the magic polarization angle for these clocks, and determine the extent to which probe laser light shifts can be suppressed. We show that the light shift and the two-photon excitation rate can be independently controlled using the probe laser polarization.

arXiv:1812.10780•Physical Review A•Jun 21, 2019•12 citations

Comparison of spontaneous emission in trapped-ion multiqubit gates at high magnetic fields

Allison L. Carter, Sean R. Muleady, Athreya Shankar +5 more

Penning traps have been used for performing quantum simulations and sensing with hundreds of ions and provide a promising route toward scaling up trapped ion quantum platforms because of the ability to trap and control hundreds or thousands of ions in two- and three-dimensional crystals. In both Penning traps and the more common radiofrequency Paul traps, lasers are often used to drive multiqubit entangling operations. A leading source of decoherence in these operations is off-resonant spontaneous emission. While many trapped ion quantum computers or simulators utilize clock qubits, other systems, especially those with high magnetic fields such as Penning traps, rely on Zeeman qubits, which require a more complex calculation of this decoherence. We therefore examine theoretically the impacts of spontaneous emission on quantum gates performed with trapped-ion ground-state Zeeman qubits in a high magnetic field. In particular, we consider two types of gates---light-shift $({\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{i}^{z}{\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{j}^{z})$ gates and M\o{}lmer-S\o{}rensen $({\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{i}^{x}{\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{j}^{x})$ gates---obtained with laser beams directed approximately perpendicular to the magnetic field (the quantization axis) and compare the decoherence errors in each. Within each gate type, we also compare different operating points with regard to the detunings, polarizations, and required intensity of the laser beams used to drive the gates. We show that both gates can have similar performance at their optimal operating conditions at high magnetic fields and examine the experimental feasibility of various operating points. By examining the magnetic field dependence of each gate, we demonstrate that, when the $P$ state fine-structure splitting is large compared to the Zeeman splittings, the theoretical performance of the M\o{}lmer-S\o{}rensen gate is significantly better than that of the light-shift gate. Additionally, for the light-shift gate, we make an approximate comparison between the fidelities that can be achieved at high fields with the fidelities of state-of-the-art two-qubit trapped ion quantum gates. We show that, with regard to spontaneous emission, the achievable infidelity with our current configuration is about an order of magnitude larger than that of the best low-field gates, but we also discuss several alternative configurations with potential error rates that are comparable with those for state-of-the-art trapped ion gates.

arXiv:2212.03367•Physical Review A•Apr 21, 2023•7 citations

In situ calibrated angle between the quantization axis and the propagating direction of the light field for trapping neutral atoms

Rui-Jun 瑞军 Guo 郭, Xiao-Dong 晓东 He 何, Cheng 诚 Sheng 盛 +7 more

The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of 85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constant-depth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic fields. Finally, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms.

Chinese Physics B•Aug 17, 2023•1 citation
In the presence of a magnetic field, hyperfine clock qubits can acquire a vector differential light shift that can be tuned via polarization to suppress the total differential light shift of high-power, off-resonant laser light. We experimentally measure this "magic" polarization condition, suppressing differential light shifts in both the 2S1/2{}^2\mathrm{S}_{1/2}2S1/2​ ground and 2F7/2o{}^2\mathrm{F}_{7/2}^o2F7/2o​ metastable clock qubits of 171Yb+^{171}\mathrm{Yb}^+171Yb+. We present calculations of the minimum bias magnetic fields required to suppress differential light shifts in the ground state clock qubits of commonly trapped ion species, finding that they are below the strengths of fields already typically present in experiments. We further present methods for metastable clock-qubit control in 171Yb+^{171}\mathrm{Yb}^+171Yb+, demonstrating a state preparation and measurement infidelity of 2.9−1.5+3.0×10−42.9^{+3.0}_{-1.5}\times10^{-4}2.9−1.5+3.0​×10−4 (−35±4 dB-35 \pm 4 \, \mathrm{dB}−35±4dB).
Trapped-ion qubits are among the most promising candidates for quantum computing, quantum information processing, and quantum simulation. In general, trapped ions are considered to have sufficiently long coherence times, which are mainly characterized under laser-free conditions. However, in reality, essential laser fields for quantum manipulation introduce residual light shift, which seriously degrades the coherence due to power fluctuations. Here, we present a comprehensive study of ac Stark shifts in the hyperfine energy levels of the Yb + 171 ion, revealing an asymmetric light shift between two circular polarizations in the clock qubit and pronounced vector light shifts in the Zeeman qubits. By precisely tuning these polarizations, a remarkable enhancement in coherence time is observed, reaching over a 100-fold for the clock qubit and more than 10-fold for the Zeeman qubits, when comparing conditions of maximum and minimum shifts. These findings advance the practical realization of scalable trapped-ion quantum processors, enabling deep quantum circuit execution and long-duration adiabatic operations.
Abstract Encoding qubit states in the ground states of zero nuclear spin trapped ions has the advantages of both long coherence time and simple energy structure. High-fidelity quantum operations on trapped-ion qubits are often hindered by the differential AC-Stark shift induced by state manipulation lasers. Here we propose and demonstrate a novel compensation approach that addresses this challenge without introducing additional laser sources or sacrificing the power of the manipulation lasers. Our method leverages an existing optical transition to induce a counteracting light shift on one of the qubit states. We experimentally validate this scheme using a single trapped 40 Ca + ion. We show that the differential AC-Stark shift induced by 393 nm Raman lasers on a ground-state Zeeman qubit can be compensated by a detuned 729 nm shelving laser. Conversely, we also demonstrate compensation of the shift induced by a 729 nm laser on a ground-to-metastable qubit using one of the 393 nm Raman beams. In both cases, the residual differential shift is suppressed by approximately two orders of magnitude compared to the uncompensated case. This method is universally applicable to various trapped-ion systems, offering a practical and power-effcient route to mitigate a key source of gate infidelity.
We demonstrate control of the differential Zeeman shift between clock states of ultracold rubidium atoms by means of nonresonant microwave dressing. Using the dc field dependence of the microwave detuning, we suppress the first- and second-order differential Zeeman shift in magnetically trapped 87Rb^{87}\mathrm{Rb}87Rb atoms. By dressing the state pair 5S1/25{S}_{1/2}5S1/2​ F=1F=1F=1, ${m}_{F}=\ensuremath{-}1$ and F=2F=2F=2, mF=1{m}_{F}=1mF​=1, a residual frequency spread of <0.1<0.1<0.1 Hz in a range of 100 mG around a chosen magnetic offset field can be achieved. This is one order of magnitude smaller than the shift of the bare states at the magic field of the Breit-Rabi parabola. We further identify double magic points, around which the clock frequency is insensitive to fluctuations both in the magnetic field and in the dressing Rabi frequency. The technique is compatible with chip-based cold-atom systems and allows the creation of clock and qubit states with reduced sensitivity to magnetic-field noise.
We find a simple solution to the problem of probe laser light shifts in two-photon optical atomic clocks. We show that there exists a magic polarization at which the light shifts of the two atomic states involved in the clock transition are identical. We calculate the differential polarizability as a function of laser polarization for two-photon optical clocks based on neutral calcium and strontium, estimate the magic polarization angle for these clocks, and determine the extent to which probe laser light shifts can be suppressed. We show that the light shift and the two-photon excitation rate can be independently controlled using the probe laser polarization.
Penning traps have been used for performing quantum simulations and sensing with hundreds of ions and provide a promising route toward scaling up trapped ion quantum platforms because of the ability to trap and control hundreds or thousands of ions in two- and three-dimensional crystals. In both Penning traps and the more common radiofrequency Paul traps, lasers are often used to drive multiqubit entangling operations. A leading source of decoherence in these operations is off-resonant spontaneous emission. While many trapped ion quantum computers or simulators utilize clock qubits, other systems, especially those with high magnetic fields such as Penning traps, rely on Zeeman qubits, which require a more complex calculation of this decoherence. We therefore examine theoretically the impacts of spontaneous emission on quantum gates performed with trapped-ion ground-state Zeeman qubits in a high magnetic field. In particular, we consider two types of gates---light-shift $({\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{i}^{z}{\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{j}^{z})$ gates and M\o{}lmer-S\o{}rensen $({\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{i}^{x}{\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\sigma}}}_{j}^{x})$ gates---obtained with laser beams directed approximately perpendicular to the magnetic field (the quantization axis) and compare the decoherence errors in each. Within each gate type, we also compare different operating points with regard to the detunings, polarizations, and required intensity of the laser beams used to drive the gates. We show that both gates can have similar performance at their optimal operating conditions at high magnetic fields and examine the experimental feasibility of various operating points. By examining the magnetic field dependence of each gate, we demonstrate that, when the PPP state fine-structure splitting is large compared to the Zeeman splittings, the theoretical performance of the M\o{}lmer-S\o{}rensen gate is significantly better than that of the light-shift gate. Additionally, for the light-shift gate, we make an approximate comparison between the fidelities that can be achieved at high fields with the fidelities of state-of-the-art two-qubit trapped ion quantum gates. We show that, with regard to spontaneous emission, the achievable infidelity with our current configuration is about an order of magnitude larger than that of the best low-field gates, but we also discuss several alternative configurations with potential error rates that are comparable with those for state-of-the-art trapped ion gates.
The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of 85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constant-depth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic fields. Finally, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms.