Quantum confined excitons in crossed electric and magnetic fields*

Achieving fully tunable quantum confinement of excitons has been a long-standing goal in optoelectronics and quantum photonics. We have recently demonstrated electrically controlled 1D quantum confinement of neutral excitons in a monolayer transition metal dichalcogenide semiconductor. This confinement relies on a combination of dc Stark effect induced by inhomogeneous in-plane electric fields and a novel polaronic confinement mechanism arising from interactions between excitons and itinerant charge carriers.

Here, we demonstrate how the combined effect of strong in-plane electric fields and out-of-plane magnetic fields leads to unexpected consequences for excitons confined in these unique potentials. Specifically, we find that the quantum confined excitons exhibit unusually large diamagnetic coefficients, which can be electrically tuned and reach values up to 2.5 µeV/T². These values imply an exciton size ~6 nm, which is strikingly enhanced compared to the 1s exciton Bohr radius ~1 nm. We envision that these unique properties could be harnessed to enhance exciton-exciton interactions and enable the realization of artificial gauge fields.