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:1409.1862 · Physical Review A

Generation of spin-motion entanglement in a trapped ion using long-wavelength radiation

Kim Lake, Sebastian Weidt, J. Randall, Eamon Standing, S. C. Webster, W. K. Hensinger

Published Jan 14, 2015• 34 citations
arXivHTMLPDF

Abstract

Applying a magnetic-field gradient to a trapped ion allows long-wavelength radiation to produce a mechanical force on the ion's motion when internal transitions are driven. We demonstrate such a coupling using a single trapped $^{171}\mathrm{Yb}^{+}$ ion and use it to produce entanglement between the spin and motional state, an essential step toward using such a field gradient to implement multiqubit operations.

DOI
10.1103/physreva.91.012319

Related papers

Design and fabrication of high magnetic field gradients towards fault tolerant two-qubit gates with trapped ions using long-wavelength radiation

Eamon Standing

In this thesis, I discuss coherent manipulation of a trapped ytterbium ion using long wavelength radiation and the results of experiments towards the performance of a two-ion entanglement gate using a static magnetic field gradient of 23.3(6) T/m to create coupling between an ion's internal state and its motion. After using these experiments to explain the requirements for high-fidelity entanglement operations, I continue by examining existing methods for creating this gradient, the current limiting factor in producing the highest fidelity operations. This includes a full characterisation of the gradients produced by symmetric scheme permanent magnets and buried current carrying wires including development of scaling laws in order to create optimum gradients for a given trap geometry. I continue by proposing a new method by which extremely high gradients over 100 T/m can be created for planar chip traps with minimal modification to an existing experiment. These gradients are tailored for axial as well as radial entanglement schemes and aim to show that the technology exists in order to produce a two-qubit gate over the fault tolerant threshold. Subsequently, I discuss the implementation of this new scheme in an experiment before constructing the apparatus to accurately align a chip with these magnets and documenting their installation into two new experimental setups. This includes a preliminary measurement of the gradient produced by an imperfect setup outside of vacuum which verifies those simulated at ~ 110 T/m. Lastly, I discuss the prospects of on-chip magnetic materials and propose a new method which when sufficiently developed should allow for high magnetic field gradients to be produced on-chip at higher ion heights than when solely using current carrying wires. Additionally this scheme should allow for switchable gradients with maximised stability in geometries previously not possible to create.

•Jul 12, 2017•0 citations

High-fidelity entanglement of trapped ions using long-wavelength radiation

Joseph Aidan Delf Randall

This thesis describes experimental work in which the spin and motional states of one and two trapped atomic ions are manipulated with long-wavelength radiation in the microwave and radio frequency (RF) regime. This allows single- and two-qubit quantum logic gates to be implemented with long-wavelength radiation, in contrast to laser frequency radiation used in the majority of work to date. The two-qubit gate scheme developed represents a significant advance towards a large scale quantum computing architecture in which laser light is not needed for coherent manipulation. An experimental setup is built in which a macroscopic linear Paul trap is fitted with permanent magnets to create a strong axial magnetic field gradient. This addition allows the spin and motional states of the ions to be coupled using long-wavelength radiation. The coherence time of qubits that are sensitive to the magnetic field gradient is increased by nearly three orders of magnitude with the use of dressed states and the lifetime and coherence time are measured to be T1 = 0.63(4) s and T2 = 0.65(5) s, respectively. Using the dressed-state qubit, sideband cooling of a single ion to the motional ground state is demonstrated, and the final mean phonon number after cooling is measured to be \bar{n} = 0.13(4). Finally, a two-qubit gate is demonstrated using the dressed-state qubits in conjunction with the magnetic field gradient, and a Bell state fidelity of F = 0.985(12) is determined. This is a significant increase in fidelity for a two-qubit gate based on long-wavelength radiation compared to previous work. The errors are analysed and it is shown that with the next generation of microfabricated traps being developed in the group, the gate fidelity using this scheme can be pushed far into the fault tolerant regime. This makes this scheme promising as an integral part of a large scale quantum computing architecture.

•Nov 1, 2015•2 citations

Entanglement on a surface chip using scalable control technologies for trapped ion qubits

Daisy Smith (9231587)

A blueprint for a scalable quantum computer using microwave radiation and a lattice of microfabricated surface ion traps was first proposed by Lekitsch et al. [1] in 2017. These surface ion traps require an integrated current-carrying wire layer which produces a variable magnetic field gradient at the position of the ions. Such a surface trap was first presented by Siegele et al. [2] in 2022. This thesis outlines the first use-case of this trap, demonstrating single-qubit control and characterization using long-wavelength radiation, and discusses the use of an Arbitrary Waveform Generator as a more scalable method for this qubit control. The thesis then characterizes the current-carrying wires, using the hyperfine states of 171Yb+ to demonstrate a variable and controllable gradient. In a magnetic field gradient, the use of a dressed state can greatly increase the coherence time of qubits, as presented by [3], the dressed state is created on this surface trap for the first time. Finally maximal entanglement of spin and motion, as proposed by Mintert and Wunderlich in [4], is shown in a single ion using long-wavelength radiation and using the current-carrying wires to produce the gradient.

•Apr 23, 2025•0 citations

Generation of entangled photons by trapped ions in microcavities under a magnetic field gradient

Mang Feng, Z. J. Deng, K. L. Gao

We propose a potential scheme to generate entangled photons by manipulating trapped ions embedded in two-mode microcavities assisted by a magnetic field gradient. By means of the spin-spin coupling due to the magnetic field gradient and the Coulomb repulsion between the ions, we show how to efficiently generate entangled photons by detecting the internal states of the trapped ions. We emphasize that our scheme is advantageous to create complete sets of entangled multiphoton states. The requirements and the experimental feasibility of our proposal are discussed in detail.

arXiv:quant-ph/0509138•Physical Review A•Oct 27, 2005•10 citations

Individual Addressing of Trapped Ions and Coupling of Motional and Spin States Using rf Radiation

M. Johanning, A. Braun, Nuala Timoney +3 more

Individual electrodynamically trapped and laser cooled ions are addressed in frequency space using radio-frequency radiation in the presence of a static magnetic field gradient. In addition, an interaction between motional and spin states induced by an rf field is demonstrated employing rf optical double resonance spectroscopy. These are two essential experimental steps towards realizing a novel concept for implementing quantum simulations and quantum computing with trapped ions.

arXiv:0801.0078•Physical Review Letters•Feb 20, 2009•130 citations

Trapped-Ion Spin-Motion Coupling with Microwaves and a Near-Motional Oscillating Magnetic Field Gradient

R. Srinivas, S. C. Burd, R. T. Sutherland +5 more

We present a new method of spin-motion coupling for trapped ions using microwaves and a magnetic field gradient oscillating close to the ions' motional frequency. We demonstrate and characterize this coupling experimentally using a single ion in a surface-electrode trap that incorporates current-carrying electrodes to generate the microwave field and the oscillating magnetic field gradient. Using this method, we perform resolved-sideband cooling of a single motional mode to its ground state.

arXiv:1812.02098•Physical Review Letters•Apr 26, 2019•53 citations
Applying a magnetic-field gradient to a trapped ion allows long-wavelength radiation to produce a mechanical force on the ion's motion when internal transitions are driven. We demonstrate such a coupling using a single trapped 171Yb+^{171}\mathrm{Yb}^{+}171Yb+ ion and use it to produce entanglement between the spin and motional state, an essential step toward using such a field gradient to implement multiqubit operations.
In this thesis, I discuss coherent manipulation of a trapped ytterbium ion using long wavelength radiation and the results of experiments towards the performance of a two-ion entanglement gate using a static magnetic field gradient of 23.3(6) T/m to create coupling between an ion's internal state and its motion. After using these experiments to explain the requirements for high-fidelity entanglement operations, I continue by examining existing methods for creating this gradient, the current limiting factor in producing the highest fidelity operations. This includes a full characterisation of the gradients produced by symmetric scheme permanent magnets and buried current carrying wires including development of scaling laws in order to create optimum gradients for a given trap geometry. I continue by proposing a new method by which extremely high gradients over 100 T/m can be created for planar chip traps with minimal modification to an existing experiment. These gradients are tailored for axial as well as radial entanglement schemes and aim to show that the technology exists in order to produce a two-qubit gate over the fault tolerant threshold. Subsequently, I discuss the implementation of this new scheme in an experiment before constructing the apparatus to accurately align a chip with these magnets and documenting their installation into two new experimental setups. This includes a preliminary measurement of the gradient produced by an imperfect setup outside of vacuum which verifies those simulated at ~ 110 T/m. Lastly, I discuss the prospects of on-chip magnetic materials and propose a new method which when sufficiently developed should allow for high magnetic field gradients to be produced on-chip at higher ion heights than when solely using current carrying wires. Additionally this scheme should allow for switchable gradients with maximised stability in geometries previously not possible to create.
This thesis describes experimental work in which the spin and motional states of one and two trapped atomic ions are manipulated with long-wavelength radiation in the microwave and radio frequency (RF) regime. This allows single- and two-qubit quantum logic gates to be implemented with long-wavelength radiation, in contrast to laser frequency radiation used in the majority of work to date. The two-qubit gate scheme developed represents a significant advance towards a large scale quantum computing architecture in which laser light is not needed for coherent manipulation. An experimental setup is built in which a macroscopic linear Paul trap is fitted with permanent magnets to create a strong axial magnetic field gradient. This addition allows the spin and motional states of the ions to be coupled using long-wavelength radiation. The coherence time of qubits that are sensitive to the magnetic field gradient is increased by nearly three orders of magnitude with the use of dressed states and the lifetime and coherence time are measured to be T1 = 0.63(4) s and T2 = 0.65(5) s, respectively. Using the dressed-state qubit, sideband cooling of a single ion to the motional ground state is demonstrated, and the final mean phonon number after cooling is measured to be \bar{n} = 0.13(4). Finally, a two-qubit gate is demonstrated using the dressed-state qubits in conjunction with the magnetic field gradient, and a Bell state fidelity of F = 0.985(12) is determined. This is a significant increase in fidelity for a two-qubit gate based on long-wavelength radiation compared to previous work. The errors are analysed and it is shown that with the next generation of microfabricated traps being developed in the group, the gate fidelity using this scheme can be pushed far into the fault tolerant regime. This makes this scheme promising as an integral part of a large scale quantum computing architecture.
A blueprint for a scalable quantum computer using microwave radiation and a lattice of microfabricated surface ion traps was first proposed by Lekitsch et al. [1] in 2017. These surface ion traps require an integrated current-carrying wire layer which produces a variable magnetic field gradient at the position of the ions. Such a surface trap was first presented by Siegele et al. [2] in 2022. This thesis outlines the first use-case of this trap, demonstrating single-qubit control and characterization using long-wavelength radiation, and discusses the use of an Arbitrary Waveform Generator as a more scalable method for this qubit control. The thesis then characterizes the current-carrying wires, using the hyperfine states of 171Yb+ to demonstrate a variable and controllable gradient. In a magnetic field gradient, the use of a dressed state can greatly increase the coherence time of qubits, as presented by [3], the dressed state is created on this surface trap for the first time. Finally maximal entanglement of spin and motion, as proposed by Mintert and Wunderlich in [4], is shown in a single ion using long-wavelength radiation and using the current-carrying wires to produce the gradient.
We propose a potential scheme to generate entangled photons by manipulating trapped ions embedded in two-mode microcavities assisted by a magnetic field gradient. By means of the spin-spin coupling due to the magnetic field gradient and the Coulomb repulsion between the ions, we show how to efficiently generate entangled photons by detecting the internal states of the trapped ions. We emphasize that our scheme is advantageous to create complete sets of entangled multiphoton states. The requirements and the experimental feasibility of our proposal are discussed in detail.
We present a new method of spin-motion coupling for trapped ions using microwaves and a magnetic field gradient oscillating close to the ions' motional frequency. We demonstrate and characterize this coupling experimentally using a single ion in a surface-electrode trap that incorporates current-carrying electrodes to generate the microwave field and the oscillating magnetic field gradient. Using this method, we perform resolved-sideband cooling of a single motional mode to its ground state.