Researchers have built an intelligent quantum sensor – the size of about 1/1000 of the cross-section of a human hair – that can simultaneously detect the intensity, polarization, and wavelength of light, tapping into the quantum properties of electrons. The breakthrough could help advance the fields of astronomy, healthcare, and remote sensing.
Twisting certain materials at specific angles can form known as “moiré materials,” which elicit previously undiscovered properties. In this case, the research team used twisted double bilayer graphene (TDBG) – that is, two atomic layers of natural stacked carbon atoms given a slight rotational twist – to build their sensing device. TDBG is critical because the twist reduces the crystal symmetry, and materials with atomic structures that are less symmetrical – in many cases – promise some intriguing physical properties that aren’t present in those with greater symmetry.
With this quantum sensor, the researchers detected a strong presence of what is known as bulk photovoltaic effect (BPVE), a process that converts light into electricity, giving a response strongly dependent on the light intensity, polarization, and wavelength. The researchers found that the BPVE in TDBG can be tuned further by external electrical means, allowing them to create “2D fingerprints” of the photovoltages for each incident light.