Fig. 3: Space-time-resolved imaging of quantum coherent interference.
From: Real-space subfemtosecond imaging of quantum electronic coherences in molecules
a, Differential conductance measurement of a PTCDA molecule constituting a monolayer on a Au(111) surface. b, Schematic illustration of space-time-resolved probing of the coherent interference between the HOMO of the PTCDA layer and the surface state of Au(111) by delay (τ) control between pulses 1 and 2. c,d, Spatially resolved topographic scans of the laser-induced tunnelling current at fixed delays of τ2 (1.2 fs, surface state; c) and τ1 (0 fs, HOMO; d). e, Spatially resolved laser-induced tunnelling current as a function of the delay between pulses 1 and 2. Scale bars, 1 nm. The d.c. bias and set-current for the constant-current operation mode of the STM are –1.8 V and 200 pA, respectively. f, Temporal evolution of the population in the HOMO and the surface state as a function of the delay between pulses 1 and 2. Solid lines are experimental results and dotted lines are the simulated temporal evolution of the population in the HOMO and the surface state using the two-state analytical model of equation (1). The error bar indicates the s.d. of the experimentally measured data from the simulated population curves (dashed curves). The reproducibility of the data in c–e was confirmed in eight individual measurements.
