2021 Sinica Open House Activity

The microscopic objects such as electron, atom, and photon obey quantum mechanical laws which are difficult to understand from the macroscopic point of view. For example, a particle can exist in a coherent superposition of two different states simultaneously. The thought experiment of Schrodinger’s cate highlights this bizarre feature. Also, the two non-commutable variables of a particle (e. g. position and velocity) cannot be precisely determined at the same time. This is called the Heisenberg uncertainty principle. Simply speaking, it is just like that “if you know where you are then you don’t know where are you going and vice versa, if you know where are you going then you don’t know where you are”. In addition, there may exist a spooky correlation between two distant particles such that when one conducts a measurement on one of the particles, the state of the other distant particle is instantly determined. This property is called the quantum entanglement. These bizarre features of quantum mechanics not only subvert our understanding of the physical world but also find their applications in quantum technologies in recent years, such as quantum metrology, quantum cryptography and quantum computing which can outperform their classical counterparts. In this talk, I will introduce this weird quantum world starting from a light source and a piece of glass. I will also introduce the principle of quantum cryptography, as well as the use of quantum light source in the precision measurement of displacement e. g. in the detection of gravitational waves.

The last 20 minutes are open for question.