A simulational model for witnessing quantum effects of gravity using IBM quantum computer

Abstract

Witnessing quantum effects in the gravitational field is found to be exceptionally difficult in practice due to lack of empirical evidence. Hence, a debate is going on among physicists whether gravity has a quantum domain or not. There had been no successful experiments at all to show the quantum nature of gravity till two recent independent works by Bose et al. [Phys. Rev. Lett. 119, 240401 (2017)] and by Marletto and Vedral [Phy. Rev. Lett. 119, 240402 (2017)]. The authors have proposed schemes to test the quantumness of gravity in two small test masses by entangling two spatially separated objects using gravitational interactions. They provide a method to witness the entanglement using spin correlation measurements, which could imply evidence for gravity being a quantum coherent mediator. Here we propose a simulational model by providing a new quantum circuit for verifying the above schemes. We simulate the schemes for the first time in IBM's 5-qubit quantum chip 'ibmqx4' by developing a quantum system which shows effects analogous to quantum gravity and calculates the degree of entanglement of the spin correlation. The entanglement witness over a range is obtained for different experimental parameters.