Unveiling the nature of spacetime remains one of the final frontiers of modern theoretical physics. I will discuss how to witness the quantum nature of gravity in a table-top experiment by creating the right witness involving the two neutral masses (spin embedded) undergoing through the Stern-Gerlach apparatus. I will discuss various challenges involved in pursuing the dream of witnessing graviton and the critical challenges. There are many challenges to be met and I will discuss the important ones: (1) To create a macroscopic quantum superposition of heavy masses via the Stern-Gerlach setup while controlling the stray gravitational acceleration and the gravity gradient noise, (2) Precise constraints on the magnetic field/current such that various electromagnetic interactions are under control, (3) Vacuum dominated Casimir effect which will create the main background for the experiment, (4) Constraints on vacuum and temperatures, (5) Feasibility of the experiment in a drop-tower, (6) The material properties and patch potentials. I will briefly discuss time scales for realising such an accelerator which will witness for the first time the graviton in a terrestrial laboratory.