Spontaneous parametric down-conversion in bottom-up grown lithium niobate microcubes
Ngoc My Hanh Duong, Grégoire Saerens, Flavia Timpu, María Teresa Buscaglia, Vincenzo Buscaglia, Andrea Morandi, Jolanda Simone Müller, Andreas Maeder, Fabian Kaufmann, Alexander S. Solntsev, Rachel Grange
Abstract
Nonclassical light sources are highly sought-after as they are an integral part of quantum communication and quantum computation devices. Typical sources use bulk nonlinear crystals that rely on stringent phase-matching conditions, limiting the operating wavelength and bandwidth. In this work, we demonstrate the generation of photon pairs from a free-standing lithium niobate microcube at the telecommunication wavelength of 1.56 µm through the spontaneous parametric down-conversion process. The maximum photon pair generation rate obtained from a single microcube with the size of 3.6 µm is 490 Hz, resulting in an efficiency of 20.6 GHz/Wm, which is three orders of magnitude larger than the efficiency of biphoton generation in bulk nonlinear crystals. The microcubes are synthesized through a solvothermal method, offering the possibility for scalable devices via bottom-up assembly on any substrates. Our work constitutes an important step forward in the realization of compact nonclassical light sources with a wide bandwidth for various quantum applications.