Spontaneous Pair Production in Ultra-Thin Materials

Strong nonlinearities in ultra-thin material can be exploited to create photon pairs. (c)Thomas Roegelsperger

As an alternative route, we are investigating spontaneous pair production in materials which do not require plasmon enhancements.  The idea here is to use new classes of materials that already possess sufficiently strong nonlinearities to realize our desired quantum effects even when the material is thinner than the wavelength of the photons involved.  One advantage of this is that many detrimental effects in spontaneous pair production experiments come from the fact that the as the photons travel through the material interactions with the material can degrade both the overall efficiency of the process and quality of the photon pairs.  In traditional photon pair sources, the efficiency loss is mitigated by phase-matching, while the quality of the pairs can be somewhat restored using so-called compensation techniques. 

In our work to date, we have been working with the transition metal dichalcogenides (TMD). This is a class of materials that can be grown as a single atomic layer. These layers can then be stacked on top of each other to enhance various properties. But most importantly for us, they have a very strong second order nonlinearity. We have already demonstrated the feasibility of producing photon pairs in such materials, and we plan to continue in this direction, primarily focusing on TMDs, but we are also interested in other ultra-thin materials.  Future work includes studying entanglement generation, temperature dependence, and clarifying the role of different internal processes on these nonlinear processes.

Publications (selected)

Quasi-phase-matched up- and down-conversion in periodically poled layered semiconductors,
C. Trovatello, C. Ferrante, B. Yang, J. Bajo, B. Braun, X. Xu, Z.H. Peng, P. K. Jenke, A. Ye, J. Park, P. Walther, L. A. Rozema, C. Dean, A. Marini, G. Cerullo, P. J. Schuck
arXiv:2312.05444 (2023).