Hot Single Photons for Quantum Communications, QuanTour ft. Carlos Antós Solanas

In this episode

• What “hot” single photons are: light emitted at room temperature, and why photons from samples cooled close to absolute zero are cleaner
• Why defects in hexagonal boron nitride can emit single photons without a cryostat, and how Carlos’s team creates them
• A European project to send room-temperature single photons 700 metres through the air for secure communication
• His path from Madrid, via Pascale Senellart’s group in Paris and 2D materials in Würzburg and Oldenburg, back to a tenure track at the Autonomous University of Madrid
• The experiment he is proudest of: two quick laser pulses that made a quantum dot emit an entangled state of photons and vacuum, with a surprising link to the Fibonacci sequence
• His wishes: less bureaucracy, unlimited funding and a good coffee machine for the lab

Key Takeaways

• Tenure-track researcher at the Autonomous University of Madrid working on ‘hot’ (room-temperature) single photons from defects in hexagonal boron nitride, alongside continued work on semiconductor quantum dots.
• Cold vs hot single photons: cooling quiets crystal vibrations to give identical, interference-ready photons; room-temperature photons carry more noise but need no cryostat, so they suit drones, cars, satellites.
• hBN is currently the front-runner room-temperature single-photon material; defects can be placed deterministically by electron irradiation of flakes.
• Advice he passes on: change material platform (a calculated risk) between PhD and postdoc, and build broad international experience and networks before setting up a group.
• Leads a QuantERA project (COMPHORT, with Tobias Heindel) targeting 700 m free-space quantum key distribution with hot single photons by 2027; wishes for less bureaucracy, more funding, and a good coffee machine.

About the guest

Carlos Antós Solanas is a Professor at the Autonomous University of Madrid in Spain, where he researches hot single photons for quantum communication, especially in hexagonal boron nitride at room temperature. After his PhD in Madrid, he was a postdoc in Pascale Senellart’s group, supported by a Marie Curie fellowship (2015 to 2019), then worked on 2D materials with Christian Schneider in Würzburg and Oldenburg (2020 to 2022), before returning to Madrid through the Atracción de Talento programme.

Carlos Antós Solanas curated the Real Scientists Nano Twitter account (@RealSci_Nano) from August 5 to August 13 2024. Read all of Carlos’s tweets from that week.