Abstract
Single quantum emitters (SQEs) are at the heart of quantum optics1 and photonic quantum-information technologies2. To date, all the demonstrated solid-state single-photon sources are confined to one-dimensional (1D; ref. 3) or 3D materials4,5,6,7. Here, we report a new class of SQEs based on excitons that are spatially localized by defects in 2D tungsten-diselenide (WSe2) monolayers. The optical emission from these SQEs shows narrow linewidths of ∼130 μeV, about two orders of magnitude smaller than those of delocalized valley excitons8. Second-order correlation measurements revealed a strong photon antibunching, which unambiguously established the single-photon nature of the emission9. The SQE emission shows two non-degenerate transitions, which are cross-linearly polarized. We assign this fine structure to two excitonic eigenmodes whose degeneracy is lifted by a large ∼0.71 meV coupling, probably because of the electron–hole exchange interaction in the presence of anisotropy10. Magneto-optical measurements also reveal an exciton g factor of ∼8.7, several times larger than those of delocalized valley excitons11,12,13,14. In addition to their fundamental importance, establishing new SQEs in 2D quantum materials could give rise to practical advantages in quantum-information processing, such as an efficient photon extraction and a high integratability and scalability.
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References
Scully, M. O. & Zubairy, M. S. Quantum Optics (Cambridge Univ. Press, 1997).
O'Brien, J. L., Furusawa, A. & Vuckovic, J. Photonic quantum technologies. Nature Photon 3, 687–695 (2009).
Högele, A., Galland, C., Winger, M. & Imamoğlu, A. Photon antibunching in the photoluminescence spectra of a single carbon nanotube. Phys. Rev. Lett. 100, 217401 (2008).
Lounis, B. & Moerner, W. E. Single photons on demand from a single molecule at room temperature. Nature 407, 491–493 (2000).
Michler, P. et al. Quantum correlation among photons from a single quantum dot at room temperature. Nature 406, 968–970 (2000).
Michler, P. et al. A quantum dot single-photon turnstile device. Science 290, 2282–2285 (2000).
Kurtsiefer, C., Mayer, S., Zarda, P. & Weinfurter, H. Stable solid-state source of single photons. Phys. Rev. Lett. 85, 290–293 (2000).
Jones, A. M. et al. Optical generation of excitonic valley coherence in monolayer WSe2 . Nature Nanotech. 8, 634–638 (2013).
Kimble, H. J., Dagenais, M. & Mandel, L. Photon antibunching in resonance fluorescence. Phys. Rev. Lett. 39, 691–695 (1977).
Gammon, D., Snow, E. S., Shanabrook, B. V., Katzer, D. S. & Park, D. Fine structure splitting in the optical spectra of single GaAs quantum dots. Phys. Rev. Lett. 76, 3005–3008 (1996).
Aivazian, G. et al. Magnetic control of valley pseudospin in monolayer WSe2 . Nature Phys. 11, 148–152 (2015).
MacNeill, D. et al. Valley degeneracy breaking by magnetic field in monolayer MoSe2 . Phys. Rev. Lett. 114, 037401 (2015).
Li, Y. et al. Valley splitting and polarization by the Zeeman effect in monolayer MoSe2 . Phys. Rev. Lett. 113, 266804 (2014).
Srivastava, A. et al. Valley Zeeman effect in elementary optical excitations of a monolayer WSe2 . Nature Phys. 11, 141–147 (2015).
Xu, X., Yao, W., Xiao, D. & Heinz, T. F. Spin and pseudospins in layered transition metal dichalcogenides. Nature Phys. 10, 343–350 (2014).
Xiao, D., Liu, G-B., Feng, W., Xu, X. & Yao, W. Coupled spin and valley physics in monolayers of MoS2 and other Group-VI dichalcogenides. Phys. Rev. Lett. 108, 196802 (2012).
Mak, K. F., He, K., Shan, J. & Heinz, T. F. Control of valley polarization in monolayer MoS2 by optical helicity. Nature Nanotech. 7, 494–498 (2012).
Cao, T. et al. Valley-selective circular dichroism of monolayer molybdenum disulphide. Nature Commun. 3, 887 (2012).
Zeng, H., Dai, J., Yao, W., Xiao, D. & Cui, X. Valley polarization in MoS2 monolayers by optical pumping. Nature Nanotech. 7, 490–493 (2012).
Mak, K. F., McGill, K. L., Park, J. & McEuen, P. L. The valley Hall effect in MoS2 transistors. Science 344, 1489–1492 (2014).
Zhang, Y. J., Oka, T., Suzuki, R., Ye, J. T. & Iwasa, Y. Electrically switchable chiral light-emitting transistor. Science 344, 725–728 (2014).
Sie, E. J. et al. Valley-selective optical Stark effect in monolayer WS2 . Nature Mater. 14, 290–294 (2015).
Kim, J. et al. Ultrafast generation of pseudo-magnetic field for valley excitons in WSe2 monolayers. Science 346, 1205–1208 (2014).
Tongay, S. et al. Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged, and free excitons. Sci. Rep. 3, 2657 (2013).
Bennett, C. H. & Brassard, G. Quantum cryptography: Public key distribution and coin tossing. Proc. IEEE Int. Conf. Computers, Systems and Signal Processing 175–179 (IEEE, 1984).
Kimble, H. J. The quantum internet. Nature 453, 1023–1030 (2008).
Knill, E., Laflamme, R. & Milburn, G. J. A scheme for efficient quantum computation with linear optics. Nature 409, 46–52 (2001).
Clark, G. et al. Vapor-transport growth of high optical quality WSe2 monolayers. APL Mater. 2, 101101 (2014).
Bayer, M. et al. Fine structure of neutral and charged excitons in self-assembled In(Ga)As/(Al)GaAs quantum dots. Phys. Rev. B 65, 195315 (2002).
Yu, H., Liu, G-B., Gong, P., Xu, X. & Yao, W. Dirac cones and Dirac saddle points of bright excitons in monolayer transition metal dichalcogenides. Nature Commun. 5, 3876 (2014).
Eigler, D. M. & Schweizer, E. K. Positioning single atoms with a scanning tunnelling microscope. Nature 344, 524–526 (1990).
Srivastava, A. et al. Optically active quantum dots in monolayer WSe2 . Nature Nanotech. http://dx.doi.org/10.1038/nnano.2015.60 (2015).
Koperski, M. et al. Single photon emitters in exfoliated WSe2 structures. Nature Nanotech. http://dx.doi.org/10.1038/nnano.2015.67 (2015).
Chakraborty, C. et al. Voltage-controlled quantum light from an atomically thin semiconductor. Nature Nanotech. http://dx.doi.org/10.1038/nnano.2015.79 (2015).
Acknowledgements
This work is supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences and the National Fundamental Research Program. The work at the University of Washington is supported by the Air Force Office of Scientific Research (FA9550-14-1-0277). G.C. is partially supported by the State of Washington through the University of Washington Clean Energy Institute. X.X. thanks the Cottrell Scholar Award for support. W.Y. is supported by the Croucher Foundation (Croucher Innovation Award) and the Research Grants Council of Hong Kong (HKU705513P, HKU9/CRF/13G).
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W.Y., X.X., C-Y.L. and J-W.P. conceived the research. Y-M.H., G.C., J.R.S., Y.H., M-C.M., Y-J.W., Q.Z., X.D., X.X. and C-Y.L. carried out the experiment. W.Y., X.X. and C-Y.L. analysed the data. G.C. prepared and characterized the samples. J.R.S., W.Y., X.X., C-Y.L. and J-W.P. co-wrote the paper with input from the other authors. W.Y., X.X., C-Y.L. and J-W.P. supervised the project.
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He, YM., Clark, G., Schaibley, J. et al. Single quantum emitters in monolayer semiconductors. Nature Nanotech 10, 497–502 (2015). https://doi.org/10.1038/nnano.2015.75
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DOI: https://doi.org/10.1038/nnano.2015.75
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