Original paper (Abstract): https://ieeexplore.ieee.org/document/8948343

I don't have access to the full paper, but I note this sentence of the abstract: "Simulations show that the device consumes very little power, with 100 times lower switching energy per unit area than DRAM, but with similar operating speeds."

So perhaps no actual devices exist, only concept and simulations?

Edit: I am reading the original via sci-hub and yes, all conclusions are based on (quite elaborate) device models.