Optical Control of Quantum Phases
Programable hyperbolic polaritons in Van der Waals semiconductors
Sternbach et al. Science, 371, 617 (2021). Article [293]
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In materials hosting both strong anisotropy and strong dipole active resonances non-intuitive optical properties can emerge. Chief among them are sub-diffractional polaritonic wave packets that can travel as conical rays with hyperbolic dispersion throughout the materials’ bulk. In our work, we utilized femtosecond photoexcitation to agitate the vdW semiconductor WSe2 and interrogated these crystals in the transient state. Our time-resolved nano-imaging data reveals key signatures of on-demand hyperbolic exciton-polaritons, appearing on the sub-picosecond timescale. These hyperbolic polaritons travel throughout the bulk of WSe2 with tunable trajectories rooted in the electronic process governing their transient electrodynamics.
Ultrafast optical switching of infrared plasmon polaritons in high-mobility graphene
Ni et al. Nature Photonics 10, 244 (2016) . Article [225]
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Cooperative photoinduced metastable phase control in strained manganite films
(with R.A. Averitt) Zhang et al. Nature Materials 15, 956 (2016) . Article [229]
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A major challenge in quantum materials is active control of quantum phases. Dynamic control with pulsed electromagnetic fields can overcome energetic barriers, enabling access to transient or metastable states that are not thermally accessible. Here we demonstrate strain-engineered tuning of La2/3Ca1/3MnO3 into an emergent charge-ordered insulating phase, where a single optical pulse can initiate a transition to a long-lived metastable hidden metallic phase. Comprehensive single-shot pulsed excitation measurements demonstrate that the transition is cooperative and ultrafast, requiring a critical absorbed photon density to activate local charge excitations that mediate magnetic–lattice coupling.