Spin and charge correlations are particularly pronounced in low-dimensional materials and enable new technologies that harness quantum behavior. Accessing these correlations on their intrinsic length and time scales is an important step towards a microscopic understanding of correlated-electron physics.
We combine scanning tunneling microscopy with pump probe schemes to achieve ultrafast spectroscopy of spin and charge dynamics with atomic spatial resolution. Using electronic pulse generation  and optical excitation with THz pulses  it is possible to achieve time resolution between milliseconds and femtoseconds thereby matching the instrument to the dynamics of the investigated system. At nanosecond time resolution, we can track the spin dynamics of magnetic atoms on surfaces and identify miniscule magnetic interactions between few-atom spin chains . At femtosecond time resolution, we can detect electron dynamics and follow the evolution of collective modes in a correlated-electron state at individual atomic defects.
These experiments access the microscopic dynamics of quantum materials and highlight pathways to design and control matter at the single atom level.
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