Details

Autor(en) / Beteiligte

• Ye, Ziliang
• Sun, Dezheng
• Heinz, Tony F

Titel

Optical manipulation of valley pseudospin

Ist Teil von

• Nature physics, 2017-01, Vol.13 (1), p.26-29

Ort / Verlag

London: Nature Publishing Group

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The coherent manipulation of spin and pseudospin underlies existing and emerging quantum technologies, including quantum communication and quantum computation1,2. Valley polarization, associated with the occupancy of degenerate, but quantum mechanically distinct valleys in momentum space, closely resembles spin polarization and has been proposed as a pseudospin carrier for the future quantum electronics3,4. Valley exciton polarization has been created in the transition metal dichalcogenide monolayers using excitation by circularly polarized light and has been detected both optically57 and electrically8. In addition, the existence of coherence in the valley pseudospin has been identied experimentally9. The manipulation of such valley coherence has, however, remained out of reach. Here we demonstrate all-optical control of the valley coherence by means of the pseudomagnetic eld associated with the optical Stark eect. Using below-bandgap circularly polarized light, we rotate the valley exciton pseudospin in monolayer WSe2 on the femtosecond timescale. Both the direction and speed of the rotation can be manipulated optically by tuning the dynamic phase of excitons in opposite valleys. This study unveils the possibility of generation, manipulation, and detection of the valley pseudospin by coupling to photons.