title: Optically excited structural transition in atomic wires on surfaces at the quantum limit.
abstract: Transient control over the atomic potential-energy landscapes of solids could lead to new states of matter and to quantum control of nuclear motion on the timescale of lattice vibrations. Recently developed ultrafast time-resolved diffraction techniques combine ultrafast temporal manipulation with atomic-scale spatial resolution and femtosecond temporal resolution. These advances have enabled investigations of photo-induced structural changes in bulk solids that often occur on timescales as short as a few hundred femtoseconds. In contrast, experiments at surfaces and on single atomic layers such as graphene report timescales of structural changes that are orders of magnitude longer. This raises the question of whether the structural response of low-dimensional materials to femtosecond laser excitation is, in general, limited. Here we show that a photo-induced transition from the low- to high-symmetry state of a charge density wave in atomic indium (In) wires supported by a silicon (Si) surface takes place within 350 femtoseconds. The optical excitation breaks and creates In-In bonds, leading to the non-thermal excitation of soft phonon modes, and drives the structural transition in the limit of critically damped nuclear motion through coupling of these soft phonon modes to a manifold of surface and interface phonons that arise from the symmetry breaking at the silicon surface. This finding demonstrates that carefully tuned electronic excitations can create non-equilibrium potential energy surfaces that drive structural dynamics at interfaces in the quantum limit (that is, in a regime in which the nuclear motion is directed and deterministic). This technique could potentially be used to tune the dynamic response of a solid to optical excitation, and has widespread potential application, for example in ultrafast detectors.
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Frigge
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Hafke
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Witte
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Krenzer
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Streubühr
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Samad Syed
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Mikšić Trontl
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Avigo
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Ligges
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: von der Linde
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Bovensiepen
authors.affiliation: Fakultät für Physik und Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Horn-von Hoegen
authors.affiliation: Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Wippermann
authors.affiliation: Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Lücke
authors.affiliation: Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Sanna
authors.affiliation: Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Gerstmann
authors.affiliation: Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany.
authors.forename: W G
authors.initials: WG
authors.lastname: Schmidt