Abstract
Competition between electron localization and delocalization in Mott insulators underpins the physics of strongly correlated electron systems. Photoexcitation, which redistributes charge, can control this many-body process on the ultrafast timescale1,2. So far, time-resolved studies have been carried out in solids in which other degrees of freedom, such as lattice, spin or orbital excitations3,4,5, dominate. However, the underlying quantum dynamics of ‘bare’ electronic excitations has remained out of reach. Quantum many-body dynamics are observed only in the controlled environment of optical lattices6,7 where the dynamics are slower and lattice excitations are absent. By using nearly single-cycle near-infrared pulses, we have measured coherent electronic excitations in the organic salt ET-F2TCNQ, a prototypical one-dimensional Mott insulator. After photoexcitation, a new resonance appears, which oscillates at 25 THz. Time-dependent simulations of the Mott–Hubbard Hamiltonian reproduce the oscillations, showing that electronic delocalization occurs through quantum interference between bound and ionized holon–doublon pairs.
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Change history
09 December 2010
In the version of this Letter originally published online, the x axis of Fig. 4a was incorrect. This has now been corrected in all versions of the Letter.
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Acknowledgements
This work was supported by the European Community Access to Research Infrastructure Action, Contract RII3-CT-2003-506350 (Centre for Ultrafast Science and Biomedical Optics, LASERLAB-EUROPE). S.R.C and D.J thank the National Research Foundation and the Ministry of Education of Singapore for support. A.A. is supported by the Royal Society. H.O. is grateful for support by a Grant-in-Aid for Scientific Research (No. 20110005) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
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S.W., D.B., H.P.E. and G.C. carried out the pump–probe experiments. D.B., S.B. and G.C. designed and built the experimental apparatus. H.U., Y.T., T.H. and H.O. provided samples. S.W. analysed the experimental data. S.R.C. and D.J. carried out the numerical simulations. S.W., A.C., A.A., S.R.C. and D.J. interpreted the data and the simulations. A.C and S.W. wrote the manuscript. A.C. conceived and coordinated the project.
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Wall, S., Brida, D., Clark, S. et al. Quantum interference between charge excitation paths in a solid-state Mott insulator. Nature Phys 7, 114–118 (2011). https://doi.org/10.1038/nphys1831
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DOI: https://doi.org/10.1038/nphys1831
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