Presented By: CM-AMO Seminars
CM-AMO Seminar |Ultrafast nano-imaging: Probing quantum dynamics in space and time
Markus Raschke (University of Colorado)
Understanding and ultimately controlling the properties of quantum materials and their coupled degrees of freedom will require counteracting the effects of dissipation and dephasing. This necessitates imaging the elementary excitations on their natural time and length scales. To achieve this goal, we developed scanning probe microscopies with ultrafast and shaped laser pulses for multiscale coherent spatio-temporal optical nano-imaging. In corresponding ultrafast movies, we resolve the fundamental quantum dynamics down to the few-femtosecond regime with nanometer spatial resolution.
Specifically, in 2D materials and their heterostructures, the emergent electronic, spin, and other quantum properties are controlled by the underlying interlayer coupling and associated charge and energy transfer dynamics. These processes are sensitive to interlayer distance and crystallographic orientation, which are in turn affected by defects, grain boundaries, and other nanoscale heterogeneities. In this talk, I will present the use of adiabatic plasmonic nanofocused four-wave mixing (FWM) [1] to image the coherent electron dynamics in monolayer WSe2 resolving nanoscale heterogeneities in dephasing ranging from T2 < 5 fs to T2 > 60 fs on length scales of 50-100 nm [2]. Further, in combination with Purcell-enhanced nano-cavity clock spectroscopy [3] in WSe2/graphene heterostructures we identify interlayer energy transfer dynamics at times scales of 350 fs [4]. Beyond the fundamental understanding to the competition between intrinsic and extrinsic effects on excitation lifetimes and coherence, we discover a new regime of nonlinear nano-optics at the interplay of spatial coherence and disorder-induced scattering.
References
[1] T. Jiang, et al., “Ultrafast coherent nonlinear nano-optics and nano-imaging of graphene”, Nature Nanotechnology 14, 838 (2019).
[2] W. Luo, et al., “Ultrafast nano-imaging of electronic coherence in monolayer WSe2” Nano Lett. 23, 1767 (2023).
[3] M. A. May, et al., “Nanocavity clock spectroscopy: resolving competing exciton dynamics in WSe2/MoSe2 heterobilayers”, Nano Lett. 21, 522 (2020).
[4] W. Luo, et al. “Nonlinear nano-imaging of interlayer coupling in 2D graphene-semiconductor heterostructures”, Small 2307345 (2024).
Specifically, in 2D materials and their heterostructures, the emergent electronic, spin, and other quantum properties are controlled by the underlying interlayer coupling and associated charge and energy transfer dynamics. These processes are sensitive to interlayer distance and crystallographic orientation, which are in turn affected by defects, grain boundaries, and other nanoscale heterogeneities. In this talk, I will present the use of adiabatic plasmonic nanofocused four-wave mixing (FWM) [1] to image the coherent electron dynamics in monolayer WSe2 resolving nanoscale heterogeneities in dephasing ranging from T2 < 5 fs to T2 > 60 fs on length scales of 50-100 nm [2]. Further, in combination with Purcell-enhanced nano-cavity clock spectroscopy [3] in WSe2/graphene heterostructures we identify interlayer energy transfer dynamics at times scales of 350 fs [4]. Beyond the fundamental understanding to the competition between intrinsic and extrinsic effects on excitation lifetimes and coherence, we discover a new regime of nonlinear nano-optics at the interplay of spatial coherence and disorder-induced scattering.
References
[1] T. Jiang, et al., “Ultrafast coherent nonlinear nano-optics and nano-imaging of graphene”, Nature Nanotechnology 14, 838 (2019).
[2] W. Luo, et al., “Ultrafast nano-imaging of electronic coherence in monolayer WSe2” Nano Lett. 23, 1767 (2023).
[3] M. A. May, et al., “Nanocavity clock spectroscopy: resolving competing exciton dynamics in WSe2/MoSe2 heterobilayers”, Nano Lett. 21, 522 (2020).
[4] W. Luo, et al. “Nonlinear nano-imaging of interlayer coupling in 2D graphene-semiconductor heterostructures”, Small 2307345 (2024).
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