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Measurement of the spin temperature of optically cooled nuclei and GaAs hyperfine constants in GaAs/AlGaAs quantum dots

Abstract

Deep cooling of electron and nuclear spins is equivalent to achieving polarization degrees close to 100% and is a key requirement in solid-state quantum information technologies1,2,3,4,5,6,7. While polarization of individual nuclear spins in diamond2 and SiC (ref. 3) reaches 99% and beyond, it has been limited to 50–65% for the nuclei in quantum dots8,9,10. Theoretical models have attributed this limit to formation of coherent ‘dark’ nuclear spin states11,12,13 but experimental verification is lacking, especially due to the poor accuracy of polarization degree measurements. Here we measure the nuclear polarization in GaAs/AlGaAs quantum dots with high accuracy using a new approach enabled by manipulation of the nuclear spin states with radiofrequency pulses. Polarizations up to 80% are observed—the highest reported so far for optical cooling in quantum dots. This value is still not limited by nuclear coherence effects. Instead we find that optically cooled nuclei are well described within a classical spin temperature framework14. Our findings unlock a route for further progress towards quantum dot electron spin qubits where deep cooling of the mesoscopic nuclear spin ensemble is used to achieve long qubit coherence4,5. Moreover, GaAs hyperfine material constants are measured here experimentally for the first time.

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Figure 1: Electron and nuclear spins in quantum dots.
Figure 2: Manipulation of the nuclear spin states in quantum dots.
Figure 3: Probing nuclear spin temperature in a quantum dot.

References

  1. 1

    Atature, M. et al. Quantum-dot spin-state preparation with near-unity fidelity. Science 312, 551–553 (2006).

    Article  Google Scholar 

  2. 2

    Jacques, V. et al. Dynamic polarization of single nuclear spins by optical pumping of nitrogen-vacancy color centers in diamond at room temperature. Phys. Rev. Lett. 102, 057403 (2009).

    CAS  Article  Google Scholar 

  3. 3

    Falk, A. L. et al. Optical polarization of nuclear spins in silicon carbide. Phys. Rev. Lett. 114, 247603 (2015).

    Article  Google Scholar 

  4. 4

    Burkard, G., Loss, D. & DiVincenzo, D. P. Coupled quantum dots as quantum gates. Phys. Rev. B 59, 2070–2078 (1999).

    CAS  Article  Google Scholar 

  5. 5

    Schliemann, J., Khaetskii, A. V. & Loss, D. Spin decay and quantum parallelism. Phys. Rev. B 66, 245303 (2002).

    Article  Google Scholar 

  6. 6

    Kurucz, Z., Sørensen, M. W., Taylor, J. M., Lukin, M. D. & Fleischhauer, M. Qubit protection in nuclear-spin quantum dot memories. Phys. Rev. Lett. 103, 010502 (2009).

    CAS  Article  Google Scholar 

  7. 7

    Roumpos, G., Master, C. P. & Yamamoto, Y. Quantum simulation of spin ordering with nuclear spins in a solid-state lattice. Phys. Rev. B 75, 094415 (2007).

    Article  Google Scholar 

  8. 8

    Gammon, D. et al. Electron and nuclear spin interactions in the optical spectra of single GaAs quantum dots. Phys. Rev. Lett. 86, 5176–5179 (2001).

    CAS  Article  Google Scholar 

  9. 9

    Chekhovich, E. A. et al. Pumping of nuclear spins by optical excitation of spin-forbidden transitions in a quantum dot. Phys. Rev. Lett. 104, 066804 (2010).

    CAS  Article  Google Scholar 

  10. 10

    Petersen, G. et al. Large nuclear spin polarization in gate-defined quantum dots using a single-domain nanomagnet. Phys. Rev. Lett. 110, 177602 (2013).

    Article  Google Scholar 

  11. 11

    Imamoḡlu, A., Knill, E., Tian, L. & Zoller, P. Optical pumping of quantum-dot nuclear spins. Phys. Rev. Lett. 91, 017402 (2003).

    Article  Google Scholar 

  12. 12

    Christ, H., Cirac, J. I. & Giedke, G. Quantum description of nuclear spin cooling in a quantum dot. Phys. Rev. B 75, 155324 (2007).

    Article  Google Scholar 

  13. 13

    Hildmann, J., Kavousanaki, E., Burkard, G. & Ribeiro, H. Quantum limit for nuclear spin polarization in semiconductor quantum dots. Phys. Rev. B 89, 205302 (2014).

    Article  Google Scholar 

  14. 14

    Goldman, M. Spin Temperature and Nuclear Magnetic Resonance in Solids (Oxford Univ. Press, 1970).

    Google Scholar 

  15. 15

    Urbaszek, B. et al. Nuclear spin physics in quantum dots: an optical investigation. Rev. Mod. Phys. 85, 79–133 (2013).

    CAS  Article  Google Scholar 

  16. 16

    Barnes, E., Cywiński, L. & Das Sarma, S. Nonperturbative master equation solution of central spin dephasing dynamics. Phys. Rev. Lett. 109, 140403 (2012).

    Article  Google Scholar 

  17. 17

    Xu, X. et al. Optically controlled locking of the nuclear field via coherent dark-state spectroscopy. Nature 459, 1105–1109 (2009).

    CAS  Article  Google Scholar 

  18. 18

    Schwager, H., Cirac, J. I. & Giedke, G. Quantum interface between light and nuclear spins in quantum dots. Phys. Rev. B 81, 045309 (2010).

    Article  Google Scholar 

  19. 19

    Atkinson, P., Zallo, E. & Schmidt, O. G. Independent wavelength and density control of uniform GaAs/AlGaAs quantum dots grown by infilling self-assembled nanoholes. J. Appl. Phys. 112, 054303 (2012).

    Article  Google Scholar 

  20. 20

    Paravastu, A. K. & Reimer, J. A. Nuclear spin temperature and magnetization transport in laser-enhanced NMR of bulk GaAs. Phys. Rev. B 71, 045215 (2005).

    Article  Google Scholar 

  21. 21

    D’Yakonov, M. I. & Perel, V. I. Optical orientation in a system of electrons and lattice nuclei in semiconductors. Theory. Sov. Phys. JETP 38, 177–183 (1974).

    Google Scholar 

  22. 22

    Chekhovich, E. A., Hopkinson, M., Skolnick, M. S. & Tartakovskii, A. I. Suppression of nuclear spin bath fluctuations in self-assembled quantum dots induced by inhomogeneous strain. Nat. Commun. 6, 6348 (2015).

    CAS  Article  Google Scholar 

  23. 23

    Ulhaq, A. et al. Vanishing electron g factor and long-lived nuclear spin polarization in weakly strained nanohole-filled GaAs/AlGaAs quantum dots. Phys. Rev. B 93, 165306 (2016).

    Article  Google Scholar 

  24. 24

    Sesti, E. L. et al. Assignments of transitions in optically-pumped NMR of GaAs/AlGaAs quantum wells on a bulk GaAs substrate. Phys. Rev. B 90, 125301 (2014).

    Article  Google Scholar 

  25. 25

    Paget, D., Amand, T. & Korb, J.-P. Light-induced nuclear quadrupolar relaxation in semiconductors. Phys. Rev. B 77, 245201 (2008).

    Article  Google Scholar 

  26. 26

    Van de Walle, C. G. & Blöchl, P. E. First-principles calculations of hyperfine parameters. Phys. Rev. B 47, 4244–4255 (1993).

    Article  Google Scholar 

  27. 27

    Yin, C. et al. Optical addressing of an individual erbium ion in silicon. Nature 497, 91–94 (2013).

    CAS  Article  Google Scholar 

  28. 28

    Gueron, M. Density of the conduction electrons at the nuclei in indium antimonide. Phys. Rev. 135, A200–A205 (1964).

    Article  Google Scholar 

  29. 29

    Paget, D., Lampel, G., Sapoval, B. & Safarov, V. I. Low field electron–nuclear spin coupling in gallium arsenide under optical pumping conditions. Phys. Rev. B 15, 5780–5796 (1977).

    CAS  Article  Google Scholar 

  30. 30

    Maletinsky, P., Kroner, M. & Imamoglu, A. Breakdown of the nuclear-spin-temperature approach in quantum-dot demagnetization experiments. Nat. Phys. 5, 407–411 (2009).

    CAS  Article  Google Scholar 

  31. 31

    Chekhovich, E. A. Structural analysis of strained quantum dots using nuclear magnetic resonance. Nat. Nanotech. 7, 646–650 (2012).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

The authors are grateful to A. Rastelli (JKU Linz), Y. Huo (HFNL Hefei), A. Waeber (TU Munich) and P. Atkinson (CNRS Paris) for fruitful discussions. This work has been supported by the EPSRC Programme Grants EP/J007544/1 and EP/N031776/1. E.A.C. was supported by a University of Sheffield Vice-Chancellor’s Fellowship and a Royal Society University Research Fellowship.

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E.Z., F.D. and O.G.S. designed and grew the samples. E.A.C. and A.U. developed the techniques and conducted the experiments. E.A.C. conceived the project and analysed the data. E.A.C. and M.S.S. wrote the manuscript with input from all authors.

Corresponding author

Correspondence to E. A. Chekhovich.

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The authors declare no competing financial interests.

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Chekhovich, E., Ulhaq, A., Zallo, E. et al. Measurement of the spin temperature of optically cooled nuclei and GaAs hyperfine constants in GaAs/AlGaAs quantum dots. Nature Mater 16, 982–986 (2017). https://doi.org/10.1038/nmat4959

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