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Integrated multi-wavelength control of an ion qubit

A Publisher Correction to this article was published on 19 January 2021

This article has been updated

Abstract

Monolithic integration of control technologies for atomic systems is a promising route to the development of quantum computers and portable quantum sensors1,2,3,4. Trapped atomic ions form the basis of high-fidelity quantum information processors5,6 and high-accuracy optical clocks7. However, current implementations rely on free-space optics for ion control, which limits their portability and scalability. Here we demonstrate a surface-electrode ion-trap chip8,9 using integrated waveguides and grating couplers, which delivers all the wavelengths of light required for ionization, cooling, coherent operations and quantum state preparation and detection of Sr+ qubits. Laser light from violet to infrared is coupled onto the chip via an optical-fibre array, creating an inherently stable optical path, which we use to demonstrate qubit coherence that is resilient to platform vibrations. This demonstration of CMOS-compatible integrated photonic surface-trap fabrication, robust packaging and enhanced qubit coherence is a key advance in the development of portable trapped-ion quantum sensors and clocks, providing a way towards the complete, individual control of larger numbers of ions in quantum information processing systems.

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Fig. 1: Ion-trap-integrated photonic elements and experimental setup.
Fig. 2: Integrated photonic beam profiles measured via microscope and subsequently verified via ion interactions in situ.
Fig. 3: Ion state detection and spectroscopy with integrated light delivery.
Fig. 4: Vibration insensitivity when delivering qubit-control light via monolithically integrated optics and direct fibre-to-chip coupling.

Data availability

All relevant data are available from the corresponding authors on request.

Change history

  • 19 January 2021

    A Correction to this paper has been published: https://doi.org/10.1038/s41586-020-03104-8

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Acknowledgements

We thank P. Murphy, C. Thoummaraj and K. Magoon for assistance with chip packaging, and P. Hassett and K. Yu for chip-facet polishing. This material is based on work supported by the Department of Defense under Air Force Contract number FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the Department of Defense.

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Authors

Contributions

J.M.S. and J.C. conceived the work. C.S.-A. and S.B. designed the integrated optical components; D.K. oversaw the fabrication of the devices. R.J.N. performed the experiments, with assistance from J.S., C.D.B., D.R., R.M., R.T.M., G.N.W. and W.L.; R.J.N. analysed the data. All authors discussed the results and contributed to writing the paper.

Corresponding authors

Correspondence to R. J. Niffenegger or J. M. Sage or J. Chiaverini.

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The authors declare no competing interests.

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Peer review information Nature thanks Jungsang Kim and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Plan view of one of the grating couplers superimposed on the trap electrode metal (partial).

The single-mode (SM) waveguide is tapered to provide a wider beam at the grating coupler. The grating teeth are formed via a partial etch into the waveguide material beneath a window in the electrode metal. The gratings used are forward-emitting, designed to emit a beam to the ion location as depicted, but 55 μm above the surface of the metal.

Extended Data Fig. 2 Integrated photonic beam profiles measured from camera-recorded images.

a, High-numerical-aperture microscope images of the beams are taken while vertically scanning the focal plane above the chip. b, c, Laser light is emitted from the grating couplers and imaged at a height of z = 0 (b) and z = 25 μm (c) above the ion-trap electrodes.

Extended Data Fig. 3 Ion interaction profile of 408-nm light, which was used as a proxy for 405-nm light.

Error bars indicate the standard error of the mean.

Extended Data Table 1 Summary of coupling and on-chip optical losses versus wavelength

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Niffenegger, R.J., Stuart, J., Sorace-Agaskar, C. et al. Integrated multi-wavelength control of an ion qubit. Nature 586, 538–542 (2020). https://doi.org/10.1038/s41586-020-2811-x

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