Fig. 2: Photon echo from quantum dots (QDs).
From: Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots
a Scheme of photon echo experiment, red arrows indicate the first and second pulses, and magenta arrow indicates direction of the PE emission. b PE decays with increasing delay time τ12 between pulses first and second for excitation with different first pulse areas Θ1. Blue, green, and dark red dots correspond to Θ1 ≈ π/2, 3π/2, and 5π/2, respectively. The second pulse area is Θ2 ≈ π. The inset shows photoluminescence spectrum for non-resonant cw excitation with photon energy ℏωexc = 2.33 eV. c–f Temporal profiles of two-pulse PE without control pulse (c), in presence of pre- (d) and post-control pulse (e, f). First and second pulses are schematically depicted in red, pre- and post-control pulses in blue and green. The pulse parameters are Θ1 ≈ π/2, Θ2 ≈ π, τ12 = 80 ps and the control pulse area is ΘC ≈ 2π.
