Rohit K Ramakrishnan
Space-based quantum technologies — spanning satellite quantum key distribution (QKD), inter-satellite optical links, quantum sensing, and distributed network nodes — demand photonic hardware that operates without cryogenic cooling, external magnetic fields, or thermally sensitive components. Transition metal dichalcogenides (TMDCs), atomically thin 2D semiconductors, present a platform inherently compatible with these constraints. Large exciton binding energies (100–500 meV) sustain excitonic resonances at room temperature, while the intrinsic valley pseudospin enables direct spin-photon coupling via helicity-dependent optical selection rules at the K⁺ and K⁻ valleys.
Pan et al. (Nature Communications, 2025) demonstrated room-temperature valley-selective emission in MoSe₂ monolayers on silicon chiral metasurfaces, achieving a record circular polarization degree of 0.5 at 294 K, independent of excitation polarization — overcoming the valley dephasing bottleneck at ambient conditions. Parallel work on strain-engineered WSe₂ has produced deterministic single-photon emitters with g²(0) < 0.03 and 92% circular polarization, with ferromagnetic proximity coupling removing the need for external magnetic fields.
Together, these advances define a nanophotonic platform — planar, silicon-foundry-compatible, and thermally passive — well suited to space deployment. This presentation reviews the physics of room-temperature valleytronics in TMDCs, surveys the state of the art across key device metrics, and identifies remaining integration challenges — spectral inhomogeneity, radiation tolerance, photon extraction efficiency, and free-space coupling — in the context of space qualification and next-generation quantum space systems.
