Matter and spin superposition in vacuum experiment (MASSIVE)

Understand

A free-falling nanodiamond containing a nitrogen vacancy centre in a spin superposition should experience a superposition of forces in an inhomogeneous magnetic field.

• We propose a practical design that brings the internal temperature of the diamond to under 10 K.
• This extends the expected spin coherence time from 2 ms to 500 ms, so the spatial superposition distance could be increased from 0.05 nm to over 1 $\mu$m, for a 1 $\mu$m diameter diamond and a magnetic inhomogeneity of only 10$^4$ T/m.
• The low temperature allows single-shot spin readout, reducing the number of nanodiamonds that need to be dropped by a factor of 10,000.