Probing quantum gravity effects with quantum mechanical oscillators

Abstract

Phenomenological models aiming to join gravity and quantum mechanics often predict effects that are potentially measurable in refined low-energy experiments. For instance, modified commutation relations between position and momentum, that account for a minimal scale length, yield a dynamics that can be codified in additional Hamiltonian terms. When applied to the paradigmatic case of a mechanical oscillator, such terms, at the lowest order in the deformation parameter, introduce a weak intrinsic nonlinearity and, consequently, deviations from the classical trajectory. This point of view has stimulated several experimental proposals and realizations, leading to meaningful upper limits to the deformation parameter. All such experiments are based on classical mechanical oscillators, i.e., excited from a thermal state. We remark indeed that decoherence, that plays a major role in distinguishing the classical from the quantum behavior of (macroscopic) systems, is not usually included in phenomenological quantum gravity models. However, it would not be surprising if peculiar features that are predicted by considering the joined roles of gravity and quantum physics should manifest themselves just on purely quantum objects. On the basis of this consideration, we propose experiments aiming to observe possible quantum gravity effects on macroscopic mechanical oscillators that are preliminary prepared in a high purity state, and we report on the status of their realization.

Quantum gravitational decoherence from fluctuating minimal length and deformation parameter at the Planck scale

“…93 . The same philosophy behind the quantum optical satellite probes is shared by laboratory tests of deformed commutation relations and other quantum gravity effects relying on systems of cavity optomechanics 94,95 , with the further advantage that optomechanical setups allow for the implementation of universal schemes for decoherence detection. Specifically, in ref.…”

Can We Detect the Quantum Nature of Weak Gravitational Fields?

“…However, GW observatories such as LIGO and Virgo are not the only candidate detectors. Cavity optomechanical systems offer complementary windows to astrophysical and spectroscopic measurements [22]. Recent proposals in phenomenological quantum gravity range from quantum gravity in electromagnetic cavities [23], quantum gravity in gravitational wave detectors [24,25], quantum table-top experiments in the lab [26], quantum gravity induced quantum entanglement [27] to interferometers with rotational sensitivity [28,29], and those sensitive to quantum spacetime geometry [30,31] (for conjectured holographic quantum geometry effects), to name but a few.…”

“…This work contains a narrow selection of topics and references. We focus on teh explicit effects of the gravitational interaction, including the interaction with a GW detector, as opposed to other phenomenological effects [22,32,39,40]. As emphasized in the Introduction, much work has been conducted on these topics over the past years and decades of work have contributed to the field of the phenomenology of quantum gravity as a whole.…”

Method for the differential measurement of phase shifts induced by atoms in an optical ring cavity

“…They have stimulated a new generation of quantum sensors including atomic clocks [9,10] and atom interferometers [11,12], which utilize the so-called spin-squeezed states [13,14] that are capable of surpassing the standard quantum limit [15] given by the number of the atoms involved [16,17]. Such nondestructive measurements also assist in the realization of nonclassical states of macroscopic systems [18,19] which can be used to probe quantum gravity effects [20]. They also help pave the way for searches of new physics beyond the standard model [21,22].…”