Researchers in Okinawa used green light to change electron spin populations in a diamond and drive a levitated mechanical assembly. The peer-reviewed Science Advances study connects spin control with motion at a mass of 128 milligrams in the authors’ preprint. A mirror measured the displacement, while control experiments tested the magnetic mechanism.
Science··Morning
Green light changes the force on a diamond
A team at Okinawa Institute of Science and Technology used electron spins in diamond to drive a levitated mechanical assembly. Spin describes an electron’s quantum angular momentum. Green light changes the populations of spin states in nitrogen-vacancy centres, defects within the diamond. In a magnetic field gradient, where the field varies with position, those changes alter the force acting on the assembly. The institute announced the peer-reviewed Science Advances study on 7 October.[1]
A mirror tracks motion of a 128 mg assembly
The authors’ 18 May preprint describes a graphite plate held above four permanent magnets and connected to a diamond through a carbon-fibre rod. A small mirror sits on the plate. The combined assembly has a mass of 128 mg, and the rod is 5 cm long. Light pulses matched to its mechanical frequency produce periodic movement. Light reflected from the mirror allows an interferometer to measure the displacement.[1]
Changing the magnet and light tests the spin mechanism
In the preprint, the vertical resonance is 17.6 Hz; with 50 mW laser power, oscillation in air reaches approximately 100 nm. The strong resonance peak vanishes when the gradient magnet is taken away. Infrared illumination at 980 nm, which affects spin polarization differently, also removes that peak. Ambient vibration limits sensitivity. The team identifies isolation, vacuum operation and improved spin control as next steps toward proposed experiments on massive quantum motion.[1]
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