Keeping the Photon in the Dark: A New Method for Full Control of Quantum Dots

Keeping the photon in the dark: A new method for full control of quantum dots

Excitons—bound pairs of electrons and an electron hole—are quasiparticles that can arise in solids. While so-called "bright" excitons emit light and are therefore accessible, dark excitons are optically inactive. As a result, they have a significantly longer lifetime—which makes them ideal for storing and controlling quantum states and using them for advanced methods to generate entanglement.

Quantum correlations of spontaneous two-photon emission from a quantum dot

Spontaneous two-photon emission (STPE) is a second-order quantum radiation process with implications in astrophysics1, atomic physics2 and quantum technology3. In particular, on-demand STPE from single quantum emitters has long been predicted to revolutionize photonic quantum science and technology4,5. Here we report STPE with brightness comparable to that of competing single-photon radiation from a single semiconductor quantum dot deterministic…

Keep­ing the pho­ton in the dark

10.07.2025 - A research team led by Gregor Weihs has developed a method for the deliberate control of dark excitons in quantum dots. Using chirped laser pulses and a magnetic field, the physicists succeeded in controlling these optically inactive quasiparticles and harnessing their unique properties for the storage and processing of quantum states.

Artificial Atoms Generate Multi-Photon Emission For Novel Light Sources

Resonant excitation of semiconductor quantum dots within micropillar cavities demonstrably produces multi-photon emission alongside single photons, a phenomenon quantified through fourth-order autocorrelation measurements and potentially mitigated by time-gated acquisition to improve the performance of single-photon sources for applications in quantum technologies.