The connection between quantum mechanics and China’s terracotta army is a lost pigment called Han Purple.
Han Purple was used more than 2800 years ago to colour the x’ian terracotta army of the Qin dynasty.
Han Purple or barium copper silicate if exposed to very high magnetic fields and very low temperatures ( under 1 degree Kelvin ) the chemical structure of the pigment enters a new state called the quantum critical point in which it actually losses a dimension and drops from 3D to 2D.
Colour invisible to the naked eye : Han Purple is found to even emit powerful rays of light in the near infra red range. Researchers of the British museum discovered that when exposed to a simple Led flash light even faint traces of the colour which are invisible to the naked eye can be seen with infra red sensors.
Lost and found : The pigment is a technological wonder made through a constant process of grinding up raw materials in precise proportions and heating it to very high temperatures. So intricate was the process that its use declined and disappeared from 220 A D. until it was rediscovered in the 90s.
So how exactly did the ancient Chinese stumble upon the intricate formula. Researchers believe that it was a by-product of the glass making process as both glass and the purple pigment contain silica and barium.
Scientists Niel Harrison said ” what these findings in barium copper silicate demonstrate is something very fundamental that may provide the key towards understanding the role of dimensionality in quantum critical phenomena”
Scientists think that dropping down from 3D to 2D has something to do with the structure of barium copper silicate. Its components are arranged like layers of tiles so they don’t stack up neatly. Each layer rules are slightly out of sync with the layer below them. This may frustrate the wave and make it go 2 dimensional.
It makes you wonder what other materials are out there, that we haven’t yet even begun to explore.