Condensation of Photons Directly into Quantum Entangled States

• Applicant: Kevin Peters, Ph.D.
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 567107833

Photon Bose-Einstein condensates (BECs) have emerged as a promising platform to explore quantum phenomena without the need for ultracold temperatures, offering a more accessible alternative to atomic BECs. However, the lack of intrinsic photon-photon interactions has limited their application in studying complex quantum many-body physics. CONDENS seeks to address this limitation by introducing effective interactions in photon BECs, enabling the exploration of new quantum regimes and the direct condensation of photons into highly entangled quantum many-body states. The primary objective of CONDENS is to demonstrate Bose-Einstein condensation of photons directly into quantum entangled states. Building on recent advances in photon BECs, this project will first explore the nonlinear dynamics of photon condensates in the mean-field limit, characterized by a large number of condensate photons. In this regime, the study will focus on demonstrating optical bistability and spontaneous mirror symmetry breaking of photon BECs in single and double-well potentials. Achieving this will provide evidence of effective photon-photon interactions and nonlinear behavior in the photon BEC. Subsequently, the project will push into the quantum domain by using highly nonlinear media to observe antibunched cavity emission, a hallmark of nonclassical light. Finally, the study aims to demonstrate entanglement in the mirror symmetry breaking of a photon BEC in a double-well potential. Direct condensation in these entangled states will be a groundbreaking achievement that could open up new avenues for quantum connectivity and quantum simulations. By realizing interactions in photon BECs and directly condensing them into entangled states, CONDENS will provide novel insights into quantum many-body systems, and pave the way towards a quantum version of the internet.

• DFG Programme: WBP Position