Measuring the speed of photons in classically forbidden regions with condensation of light

Quantum tunneling is one of the most fundamental quantum phenomena, playing a significant role in quantum computing, modern electronics, and quantum biology. However, it is still not fully understood, in particular in the context of tunneling speed. Here, we suggest a new way to measure the speed of photons in classically forbidden and allowed regions. For this purpose, we use the photon Bose-Einstein Condensation (pBEC) obtained in a microcavity system. Using direct laser writing technique for mirror nanostructuring, we implement a system of waveguides, forming a 2D photon gas. In such a system we can directly measure the tunneling wavefunction, part of which is transmitted through the mirrors, which is not easily achievable in other systems.