Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Control and readout of a superconducting qubit using a photonic link

Abstract

Delivering on the revolutionary promise of a universal quantum computer will require processors with millions of quantum bits (qubits)1,2,3. In superconducting quantum processors4, each qubit is individually addressed with microwave signal lines that connect room-temperature electronics to the cryogenic environment of the quantum circuit. The complexity and heat load associated with the multiple coaxial lines per qubit limits the maximum possible size of a processor to a few thousand qubits5. Here we introduce a photonic link using an optical fibre to guide modulated laser light from room temperature to a cryogenic photodetector6, capable of delivering shot-noise-limited microwave signals directly at millikelvin temperatures. By demonstrating high-fidelity control and readout of a superconducting qubit, we show that this photonic link can meet the stringent requirements of superconducting quantum information processing7. Leveraging the low thermal conductivity and large intrinsic bandwidth of optical fibre enables the efficient and massively multiplexed delivery of coherent microwave control pulses, providing a path towards a million-qubit universal quantum computer.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Photonic link concept.
Fig. 2: Qubit readout and control with a photonic link.
Fig. 3: Photocurrent shot noise measurement.
Fig. 4: Qubit scaling comparison.

Data availability

The experimental data and numerical simulations presented here are available from the corresponding authors upon request.

References

  1. 1.

    Fowler, A. G., Mariantoni, M., Martinis, J. M. & Cleland, A. N. Surface codes: towards practical large-scale quantum computation. Phys. Rev. A 86, 032324 (2012).

    ADS  Google Scholar 

  2. 2.

    Reiher, M., Wiebe, N., Svore, K. M., Wecker, D. & Troyer, M. Elucidating reaction mechanisms on quantum computers. Proc. Natl Acad. Sci. USA 114, 7555–7560 (2017).

    ADS  CAS  Google Scholar 

  3. 3.

    Gidney, C. & Ekerå, M. How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits. Preprint at https://arxiv.org/abs/1905.09749 (2019).

  4. 4.

    Krantz, P. et al. A quantum engineer’s guide to superconducting qubits. Appl. Phys. Rev. 6, 021318 (2019).

    ADS  Google Scholar 

  5. 5.

    Krinner, S. et al. Engineering cryogenic setups for 100-qubit scale superconducting circuit systems. EPJ Quantum Technol. 6, 2 (2019).

    Google Scholar 

  6. 6.

    Davila-Rodriguez, J. et al. High-speed photodetection and microwave generation in a sub-100-mK environment. In 2019 Conf. Lasers and Electro-Optics (CLEO) SF2N.1 (2019)

  7. 7.

    Devoret, M. H. & Schoelkopf, R. J. Superconducting circuits for quantum information: an outlook. Science 339, 1169–1174 (2013).

    ADS  CAS  Google Scholar 

  8. 8.

    Ofek, N. et al. Extending the lifetime of a quantum bit with error correction in superconducting circuits. Nature 536, 441–445 (2016).

    ADS  CAS  Google Scholar 

  9. 9.

    Arute, F. et al. Quantum supremacy using a programmable superconducting processor. Nature 574, 505–510 (2019).

    ADS  CAS  Google Scholar 

  10. 10.

    Andersen, C. K. et al. Repeated quantum error detection in a surface code. Nat. Phys. 16, 875–880 (2020).

    CAS  Google Scholar 

  11. 11.

    Blais, A., Girvin, S. M. & Oliver, W. D. Quantum information processing and quantum optics with circuit quantum electrodynamics. Nat. Phys. 16, 247–256 (2020).

    CAS  Google Scholar 

  12. 12.

    Andrews, R. W. et al. Bidirectional and efficient conversion between microwave and optical light. Nat. Phys. 10, 321–326 (2014).

    CAS  Google Scholar 

  13. 13.

    Rueda, A. et al. Efficient microwave to optical photon conversion: an electro-optical realization. Optica 3, 597–604 (2016).

    ADS  CAS  Google Scholar 

  14. 14.

    Jiang, W. et al. Efficient bidirectional piezo-optomechanical transduction between microwave and optical frequency. Nat. Commun. 11, 1166 (2020).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  15. 15.

    Mirhosseini, M., Sipahigil, A., Kalaee, M. & Painter, O. Superconducting qubit to optical photon transduction. Nature 588, 599–603 (2020).

    ADS  CAS  Google Scholar 

  16. 16.

    Magnard, P. et al. Microwave quantum link between superconducting circuits housed in spatially separated cryogenic systems. Phys. Rev. Lett. 125, 260502 (2020).

    ADS  CAS  Google Scholar 

  17. 17.

    Tuckerman, D. B. et al. Flexible superconducting Nb transmission lines on thin film polyimide for quantum computing applications. Supercond. Sci. Technol. 29, 084007 (2016).

    ADS  Google Scholar 

  18. 18.

    Smith, J. P. et al. Flexible coaxial ribbon cable for high-density superconducting microwave device arrays. IEEE Trans. Appl. Supercond. 31, 2500105 (2021).

    CAS  Google Scholar 

  19. 19.

    McDermott, R. et al. Quantum–classical interface based on single flux quantum digital logic. Quantum Sci. Technol. 3, 024004 (2018).

    ADS  Google Scholar 

  20. 20.

    Leonard, E. et al. Digital coherent control of a superconducting qubit. Phys. Rev. Appl. 11, 014009 (2019).

    ADS  CAS  Google Scholar 

  21. 21.

    Bardin, J. C. et al. Design and characterization of a 28-nm bulk-CMOS cryogenic quantum controller dissipating less than 2 mW at 3 K. IEEE J. Solid-State Circuits 54, 3043–3060 (2019).

    ADS  Google Scholar 

  22. 22.

    Youssefi, A. et al. Cryogenic electro-optic interconnect for superconducting devices. Preprint at https://arxiv.org/abs/2004.04705 (2020).

  23. 23.

    de Cea, M. et al. Photonic readout of superconducting nanowire single photon counting detectors. Sci. Rep. 10, 9470 (2020).

    ADS  PubMed  PubMed Central  Google Scholar 

  24. 24.

    Capmany, J. & Novak, D. Microwave photonics combines two worlds. Nat. Photon. 1, 319–330 (2007).

    ADS  CAS  Google Scholar 

  25. 25.

    Saleh, B. E. A. & Teich, M. C. Fundamentals of Photonics (Wiley-Interscience, 2007).

  26. 26.

    Koch, J. et al. Charge-insensitive qubit design derived from the Cooper pair box. Phys. Rev. A 76, 042319 (2007).

    ADS  Google Scholar 

  27. 27.

    Paik, H. et al. Observation of high coherence in Josephson junction qubits measured in a three-dimensional circuit QED architecture. Phys. Rev. Lett. 107, 240501 (2011).

    ADS  Google Scholar 

  28. 28.

    Walter, T. et al. Rapid high-fidelity single-shot dispersive readout of superconducting qubits. Phys. Rev. Appl. 7, 054020 (2017).

    ADS  Google Scholar 

  29. 29.

    Claudon, J., Balestro, F., Hekking, F. W. J. & Buisson, O. Coherent oscillations in a superconducting multilevel quantum system. Phys. Rev. Lett. 93, 187003 (2004).

    ADS  CAS  Google Scholar 

  30. 30.

    Schuster, D. I. et al. a.c. Stark shift and dephasing of a superconducting qubit strongly coupled to a cavity field. Phys. Rev. Lett. 94, 123602 (2005).

    ADS  CAS  Google Scholar 

  31. 31.

    Gambetta, J. et al. Qubit–photon interactions in a cavity: measurement-induced dephasing and number splitting. Phys. Rev. A 74, 042318 (2006).

    ADS  Google Scholar 

  32. 32.

    Yan, F. et al. The flux qubit revisited to enhance coherence and reproducibility. Nat. Commun. 7, 12964 (2016).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  33. 33.

    Winzer, P. J., Neilson, D. T. & Chraplyvy, A. R. Fiber-optic transmission and networking: the previous 20 and the next 20 years. Opt. Express 26, 24190–24239 (2018).

    ADS  CAS  Google Scholar 

  34. 34.

    Preskill, J. Quantum computing in the NISQ era and beyond. Quantum 2, 79 (2018).

    Google Scholar 

  35. 35.

    Smith, T. L., Anthony, P. J. & Anderson, A. C. Effect of neutron irradiation on the density of low-energy excitations in vitreous silica. Phys. Rev. B 17, 4997 (1978).

    ADS  CAS  Google Scholar 

  36. 36.

    Gambetta, J. et al. Quantum trajectory approach to circuit QED: quantum jumps and the Zeno effect. Phys. Rev. A 77, 012112 (2008).

    ADS  Google Scholar 

  37. 37.

    Clerk, A. A. & Utami, D. W. Using a qubit to measure photon-number statistics of a driven thermal oscillator. Phys. Rev. A 75, 042302 (2007).

    ADS  Google Scholar 

  38. 38.

    Houck, A. A. et al. Controlling the spontaneous emission of a superconducting transmon qubit. Phys. Rev. Lett. 101, 080502 (2008).

    ADS  CAS  Google Scholar 

  39. 39.

    Nigg, S. E. et al. Black-box superconducting circuit quantization. Phys. Rev. Lett. 108, 240502 (2012).

    ADS  Google Scholar 

  40. 40.

    Boyd, R. W. Radiometry and the Detection of Optical Radiation (Wiley, 1983).

  41. 41.

    Yariv, A. & Yeh, P. Photonics: Optical Electronics in Modern Communications 5th edn (Oxford Univ. Press, 1997).

  42. 42.

    Lecocq, F. et al. Nonreciprocal microwave signal processing with a field-programmable Josephson amplifier. Phys. Rev. Appl. 7, 024028 (2017).

    ADS  Google Scholar 

  43. 43.

    W. Liu, R. Cendejas, H. Cao, Q. Hang, Z. Ji, and A. Nikolov, Uncooled low-bias uni-traveling carrier photodetectors. In 2013 Conf. Lasers and Electro-Optics (CLEO) Science and Innovations OSA Technical Digest CTh3L.2 (OSA 2013).

  44. 44.

    Zielinski, E., Schweizer, H., Streubel, K., Eisele, H. & Weimann, G. Excitonic transitions and exciton damping processes in InGaAs/InP. J. Appl. Phys. 59, 2196 (1986).

    ADS  CAS  Google Scholar 

  45. 45.

    Yeh, J.-H., LeFebvre, J., Premaratne, S., Wellstood, F. C. & Palmer, B. S. Microwave attenuators for use with quantum devices below 100 mK. J. Appl. Phys. 121, 224501 (2017).

    ADS  Google Scholar 

  46. 46.

    Wang, Z. et al. Cavity attenuators for superconducting qubits. Phys. Rev. Appl. 11, 014031 (2019).

    ADS  CAS  Google Scholar 

  47. 47.

    Serniak, K. et al. Direct dispersive monitoring of charge parity in offset-charge-sensitive transmons. Phys. Rev. Appl. 12, 014052 (2019).

    ADS  CAS  Google Scholar 

  48. 48.

    Córcoles, A. D. et al. Protecting superconducting qubits from radiation. Appl. Phys. Lett. 99, 181906 (2011).

    ADS  Google Scholar 

Download references

Acknowledgements

We thank J. Davila-Rodriguez, J. Campbell and E. Ivanov for early contributions to this work. We thank S. W. Nam and K. Lehnert for comments on the manuscript. This work was supported by the NIST Quantum Information Program.

Author information

Affiliations

Authors

Contributions

F.L., F.Q., J.A., S.A.D. and J.D.T. conceived and designed the experiment. F.L., F.Q. and J.D.T. built the experimental set-up. F.L. performed the experiment and F.L., F.Q. and J.D.T. analysed the data. K.C. fabricated the transmon qubit. All authors contributed to the manuscript.

Corresponding authors

Correspondence to F. Lecocq, F. Quinlan or J. D. Teufel.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Joseph Bardin, Blake Johnson and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Relaxation time in the presence of optical light.

Histogram of 280 measurements of the relaxation time of the qubit with 2 μW of optical power applied to the photodiode during the qubit evolution. Comparison with data in the absence of optical power confirm that the qubit relaxation time is not affected by stray optical photons, with an average relaxation time T1 ≈ 43 μs. Data were acquired using the set-up in Fig. 2a.

Extended Data Fig. 2 Photodiode current–voltage characteristic.

Measured d.c. current through the photodiode as a function of voltage bias, in the absence of optical power. The dark current is below the 10-pA resolution of the current meter.

Extended Data Fig. 3 Vector control with the photonic link.

Ramsey oscillation driven by the photonic link, as a function of the phase θ of the second π/2 pulse (same set-up as Fig. 2d). Data (dots) follow a clean sinusoidal dependence (line). \({R}_{x}^{{\rm{\pi }}/2}\) denotes a π/2 qubit rotation around the x axis and \({R}_{\theta }^{{\rm{\pi }}/2}\) denotes a π/2 qubit rotation around an axis with a variable angle θ within the xy plane. qb, qubit; cav., cavity.

Extended Data Fig. 4 Dilution refrigerator wiring.

Details of the circuitry employed in the cryostat for qubit measurement and control experiments. The qubit cavity device is placed inside a double layer cryoperm shield. FPJA, field-programmable Josephson amplifier (see text); HEMT, high-electron-mobility transistor amplifier, LPF, low-pass filter.

Extended Data Fig. 5 Simplified room-temperature set-up.

The FPJA pump, cavity local oscillator (LO) and demodulation LO share a 1-GHz reference clock and are locked to all other instruments via a 10-MHz reference clock. A master trigger, not shown, is shared via a distribution amplifier. There are slight differences in the set-up between the qubit control and measurement experiments. Amplification and attenuation levels are slightly different. The FPJA pump is pulsed on only during the qubit measurement. AWG, arbitrary waveform generator; BPF, band-pass filter; DR, dilution refrigerator; LPF, low-pass filter; VNA, vector network analyser.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lecocq, F., Quinlan, F., Cicak, K. et al. Control and readout of a superconducting qubit using a photonic link. Nature 591, 575–579 (2021). https://doi.org/10.1038/s41586-021-03268-x

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing