Electric-field tunable fine-structure splitting in monolayer semiconductors*

Semiconducting quantum dots (QDs) are among the most promising source of on-demand, indistinguishable single and entangled photon source which are the basic ingredients for quantum communications and computing applications¹. The most common approach to generate entangled photon pairs in QDs is to utilize the biexciton to exciton radiative cascade². Recently, single confined exciton and biexciton emission have been demonstrated at locally strained sites in semiconducting two-dimensional (2D) materials^3-5. The 2D host makes them ideal for integrated quantum photonics studies. However, a sizable fine-structure splitting (FSS) (~800 ueV) due to anisotropic electron-hole exchange interaction in these quantum-confined excitons and biexcitons poses a limit to the indistinguishability of the generated photon pairs. We demonstrate a suppression of the FSS by leveraging on van der Waals heterostructure and fabricate a voltage tunable device to minimize the effect of exchange interaction.
1. Nat. Phot. 1, 215 (2007)
2. Nat. Phy. 6, 947 (2010)
3. Nat. Nano. 10, 507 (2015)
4. Nat. Comm. 8, 15093 (2017)
5. Nat, Comm. 7, 13409 (2016)