Stress enhances quantum dot performance, QuanTour ft. Rinaldo Trotta

In this episode

• Why Rinaldo’s group puts quantum dots under stress, and electric and magnetic fields, to make them emit pairs of entangled photons
• What entanglement is, explained with two dice that always land on the same number
• How entanglement swapping could carry secure quantum communication beyond 100 km, and one day around the globe
• His path from Sapienza University of Rome, via Dresden and Linz, back to Rome with an ERC Starting Grant, building a lab from empty rooms twice
• The discovery he is proudest of: using two stresses, one to rotate and one to make symmetric, so any quantum dot can be tuned to emit entangled photons
• Teaching quantum science to international students, and his wishes: less bureaucracy, more time in the lab and permanent positions for young researchers

Key Takeaways

• Professor at Sapienza University of Rome; deliberately stresses epitaxial quantum dots with strain, electric and magnetic fields to force them to emit entangled photons for long-distance secure quantum communication.
• Entanglement explained with dice: two entangled particles give individually random but perfectly correlated results, and no third party can take a share.
• Long-distance links can’t use amplifiers (no-cloning); entanglement swapping between repeater nodes (and satellites, demonstrated in China) extends range beyond ~100 km.
• Long history with Armando Rastelli (met in Dresden, followed him to Linz); built two labs from empty rooms, stressful but fun.
• Three wishes: more time for research and teaching (less bureaucracy) and permanent positions for young researchers so brilliant people aren’t lost from academia.

About the guest

Rinaldo Trotta is a Professor at Sapienza University of Rome in Italy, where his research on semiconductor nanostructures sits at the interface between semiconductor physics and quantum optics. Before returning to Rome, he worked in Linz, Austria.

Rinaldo Trotta curated the Real Scientists Nano Twitter account (@RealSci_Nano) from May 27 to June 3 2024. Read all of Rinaldo’s tweets from that week.