A promising route to testing quantum gravity in the laboratory is to look for gravitationally-induced entanglement (GIE) between two or more quantum matter systems. Proposals for such tests have principally used microsolid systems, with highly non-classical states, such as N00N states or highly-squeezed states. Here, we consider, for the first time, GIE between two atomic gas interferometers as a test of quantum gravity. We propose placing the two interferometers next to each other in parallel and looking for correlations in the number of atoms at the output ports as evidence of GIE and quantum gravity. GIE is possible without challenging macroscopic superposition states, such as N00N or Schrödinger cat states, and instead there can be just classical-like 'coherent' states of atoms. This requires the total mass of the atom interferometers to be on the Planck mass scale, and long integration times. However, with current state-of-the-art quantum squeezing in cold atoms, we argue that the mass scale can be reduced to approachable levels and detail how such a mass scale can be achieved in the near future.

https://arxiv.org/abs/2304.00734

Engineering synthetic dimensions, where the physics of additional spatial dimensions is simulated within the internal states of a quantum system, allows the realisation of phenomena not otherwise accessible in experiments. Ultracold ground-state polar molecules are an ideal platform to encode synthetic dimensions, offering access to large Hilbert spaces of long-lived internal states associated with the rotational and hyperfine degrees of freedom, that can be coupled together with microwave fields to simulate tunnelling.

https://arxiv.org/abs/2604.00745

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