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Large-scale integration of artificial atoms in hybrid photonic circuits


A central challenge in developing quantum computers and long-range quantum networks is the distribution of entanglement across many individually controllable qubits1. Colour centres in diamond have emerged as leading solid-state ‘artificial atom’ qubits2,3 because they enable on-demand remote entanglement4, coherent control of over ten ancillae qubits with minute-long coherence times5 and memory-enhanced quantum communication6. A critical next step is to integrate large numbers of artificial atoms with photonic architectures to enable large-scale quantum information processing systems. So far, these efforts have been stymied by qubit inhomogeneities, low device yield and complex device requirements. Here we introduce a process for the high-yield heterogeneous integration of ‘quantum microchiplets’—diamond waveguide arrays containing highly coherent colour centres—on a photonic integrated circuit (PIC). We use this process to realize a 128-channel, defect-free array of germanium-vacancy and silicon-vacancy colour centres in an aluminium nitride PIC. Photoluminescence spectroscopy reveals long-term, stable and narrow average optical linewidths of 54 megahertz (146 megahertz) for germanium-vacancy (silicon-vacancy) emitters, close to the lifetime-limited linewidth of 32 megahertz (93 megahertz). We show that inhomogeneities of individual colour centre optical transitions can be compensated in situ by integrated tuning over 50 gigahertz without linewidth degradation. The ability to assemble large numbers of nearly indistinguishable and tunable artificial atoms into phase-stable PICs marks a key step towards multiplexed quantum repeaters7,8 and general-purpose quantum processors9,10,11,12.

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Fig. 1: Scalable integration of artificial atoms with photonics.
Fig. 2: Fabrication and integration of QMC with integrated photonics.
Fig. 3: Integrated quantum photonics with colour centres.
Fig. 4: Defect-free arrays of optically coherent and efficient waveguide-coupled emitters.
Fig. 5: Controlling the optical transitions of colour centres on a PIC.

Data availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. The data that support the findings of this study are also openly available in figshare at


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The focused ion beam implantation work was performed at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the US DOE’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the US DOE or the United States Government. This work made use of the Shared Experimental Facilities supported in part by the MRSEC Program of the National Science Foundation (NSF) under award number DMR - 1419807. We thank D. Perry for providing the focused ion beam implantation at Sandia National Laboratories, and D. Zhu and C. Peng for assistance with wire bonding. N.H.W. acknowledges support from the Army Research Laboratory (ARL) Center for Distributed Quantum Information (CDQI) programme W911NF-15-2-0067. T.-J. L. acknowledges support from the Department of Defense (DOD) National Defense Science and Engineering Graduate Fellowship (NDSEG) as well as the Air Force Research Laboratory RITA programme FA8750-16-2-0141. K.C.C. acknowledges funding support by the NSF Graduate Research Fellowships Program and ARL CDQI. M.P.W. acknowledges support from the NSF Center for Integrated Quantum Materials (CIQM), NSF grant number DMR-1231319. M.T. acknowledges support by an appointment to the Intelligence Community Postdoctoral Research Fellowship Program at the Massachusetts Institute of Technology, administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US DOE and the Office of the Director of National Intelligence. L.D.S acknowledges support from the Under Secretary of Defense for Research and Engineering administered through the MIT Lincoln Laboratory Technology Office. E.A.B. was supported by a NASA Space Technology Research Fellowship and the NSF Center for Ultracold Atoms (PHY-1734011). I.B.H is supported by the DOE ‘Photonics at Thermodynamic Limits’ Energy Frontier Research Center under grant DE-SC0019140. S.L.M was supported by the NSF EFRI ACQUIRE programme EFMA-1641064. I.R.C. acknowledges funding support from the DOD NDSEG Fellowship, NSF award DMR-1747426, and the NSF EFRI ACQUIRE programme EFMA-1641064. D.E. acknowledges partial support from the MITRE Quantum Moonshot initiative.

Author information




N.H.W., T.-J.L. and D.E. conceived the experiments and wrote the manuscript. N.H.W. and T.-J.L. fabricated the devices, performed the experiments, and analysed the data, with fabrication assistance from K.C.C. and experimental assistance from M.P.W., M.E.T., L.D.S., E.A.B., I.B.H., S.L.M., and I.R.C. E.S.B. performed ion implantation. D.E. supervised the project. All authors discussed the results and contributed to the manuscript.

Corresponding authors

Correspondence to Noel H. Wan, Tsung-Ju Lu or Dirk Englund.

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The authors declare no competing interests.

Additional information

Peer review information Nature thanks Wolfram Pernice, Jennifer Choy 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 Flowchart for large-scale heterogeneous integration.

See main text and methods for process descriptions.

Extended Data Fig. 2 Histogram of number of emitter-coupled waveguides within a QMC.

The red coloured bar corresponds to the defect-free 8-channel QMCs that were suitable for integration. The orange coloured bars correspond to the QMCs that we did not use in this work.

Extended Data Fig. 3 FDTD simulation showing propagation of light from the diamond waveguide into the AlN waveguide.

a, For a 602-nm wavelength (corresponding to the GeV colour centre ZPL). b, For a 737-nm wavelength (corresponding to the SiV colour centre ZPL).

Extended Data Fig. 4 Saturation response of a single GeV centre.

a, Continuous-wave 532-nm laser excitation b, Pulsed laser excitation at 532 nm with a repetition rate of 26 MHz.

Extended Data Fig. 5 Scheme for strain-tuning emitters in a PIC platform.

a, SEM image of type I and type II waveguides considered in this experiment. b, Strain distribution along the waveguides and emitters considered in the main text (Fig. 5). Horizontal error bars indicate the lateral uncertainty in the position of emitters and vertical error bars indicate the ion implantation straggle.

Extended Data Fig. 6 Spectral shift of GeV centres in response to strain fields.

ac, Strain response of emitter 1A (a), emitter 1B (b) and emitter 2 (c).

Extended Data Fig. 7 Spectral shifts for the brightest transitions.

Reproducible spectral shifts between 10 V and 26 V for the two brightest transitions C and D for emitter 2.

Extended Data Fig. 8 Optical properties during strain tuning.

Top: PLE linewidths as a function of voltage. Bottom: corresponding frequency shift, Δν, of the ZPL transition.

Extended Data Fig. 9 Stability of the ZPL transition frequency during strain tuning.

Each time slice corresponds to a single PLE linewidth measurement averaged over 2,000 experiments (about 3 min).

Extended Data Table 1 Saturated count rates from single GeV centres in a QMC

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Wan, N.H., Lu, TJ., Chen, K.C. et al. Large-scale integration of artificial atoms in hybrid photonic circuits. Nature 583, 226–231 (2020).

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