Direct observation of ultraslow hyperbolic polariton propagation with negative phase velocity

1. Yoxall, E.
2. Schnell, M.
3. Nikitin, A.Y.
4. Txoperena, O.
5. Woessner, A.
6. Lundeberg, M.B.
7. Casanova, F.
8. Hueso, L.E.
9. Koppens, F.H.L.
10. Hillenbrand, R.