A new review paper in Nature Photonics suggests that ultrathin materials could enable the development of programmable quantum light circuits. These circuits could be essential for next-generation quantum technologies, such as quantum neural networks and distributed quantum computing. The study was led by researchers Igor Aharonovich from the University of Technology Sydney, Ken Crozier from the University of Melbourne, and Dragomir Neshev from the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS). They highlight how photonics — the science of generating and controlling light — could play a pivotal role in the future of quantum technology. While many photonic components already exist, the challenge is in integrating and assembling them in a way that allows flexible and efficient manipulation after manufacturing. The review emphasizes a shift from fixed, static quantum devices to more adaptable, multifunctional circuits. This is a key part of the second quantum revolution, which aims to move quantum technologies from experimental setups to practical, scalable systems. Photonics is particularly promising because it offers low decoherence — the loss of quantum information — and can carry information encoded in complex quantum states. The researchers stress that achieving programmable quantum circuits is essential for making quantum optics more robust and practical for real-world applications. However, a major hurdle is creating systems that can perform multiple functions simultaneously, which is crucial for programmability. One of the key components discussed in the review is tunable quantum light sources, which must generate entangled photons and precisely control their properties, such as frequency, amplitude, phase, and polarization. Van der Waals crystals — materials made of layered structures that can be manipulated by twisting or rearranging the layers — are highlighted for their tunability. Researchers have developed microscopic mechanical systems that can adjust these crystals and other components on a chip. However, van der Waals crystals still lag behind current leaders like quantum dots and color centers in terms of brightness, purity of photons, and coherence. More research and development are needed to improve their performance. Another critical element is the dynamic modulation of components, which is essential for controlling phase and frequency in quantum circuits. Traditional methods are often bulky, inefficient, and slow. While some new approaches are addressing these issues, no single material platform currently meets all the necessary requirements for efficient energy coupling, ultrafast switching, and scalability. The researchers believe that two-dimensional (2D) materials could eventually fulfill these criteria. These materials allow for precise engineering of properties such as bandgaps, nonlinear optical effects, and quantum light emission. Aharonovich suggests that future quantum circuits could be built entirely from 2D materials, offering a flexible toolkit for controlling quantum light and enabling new technological advancements.