Bounding quantum-gravity-inspired decoherence using atom interferometry

Abstract

Hypothetical models have been proposed in which explicit collapse mechanisms prevent the superposition principle from holding at large scales. In particular, the model introduced by Ellis et al. [J. Ellis et al., Phys. Lett. B 221, 113 (1989)] suggests that quantum gravity might be responsible for the collapse of the wave function of massive objects in spatial superpositions. We consider here a recent experiment reporting on interferometry with atoms delocalized over half a meter for a time scale of 1 s [T. Kovachy et al., Nature (London) 528, 530 (2015)] and show that the corresponding data strongly bound quantum-gravity-induced decoherence and rule it out in the parameter regime considered originally.

Macroscopic quantum states: Measures, fragility, and implementations

“…Leggett (2002) claims about the SQUID experiments that "any reasonable" measure for macroscopic quantum states would assign an effective size that is in the order of the number of involved electrons. For the experiments Friedman et al (2000); van der Wal et al (2000), this is 10 10 (in units of Bohr magneton in the case of Leggett's extensive difference). Knee et al (2016) found an extensive difference of roughly 1.3 × 10 5 in units of Bohr magneton for their experiment.…”

“…This number is strongly contrasted by Marquardt et al (2008) using their framework. Analyzing only van der Wal et al (2000), the authors find an effective size between one and two, that is, it suffices to apply at most two basic steps to map, say, the clockwise circulating state to the anticlockwise one. Similarly low is the number found by Nimmrichter et al (2011), who assign an effective size of µ ≈ 5 to the experiment of Friedman et al (2000).…”

“…21 (b) for the theoretical prediction). Note that other experiments, for example, Hime et al (2006); van der Wal et al (2000) differ in the details, but also work with a double-well potential and prove the coherence via an avoided crossing.…”

Study of temporal quantum correlations in decoheringBandKmeson systems

“…Decoherence, here, is modelled by a single phenomenological parameter [56] which represents the interaction between the one-particle system and its environment. The environment can be attributed to quantum gravity effects [57][58][59][60][61][62][63][64] or it can be due to detector background itself. Apart from decoherence, we also include the effects of CP violation.…”

Testing unconventional decoherence models with atoms in optical lattices

“…by atom interferometers with large momentum transfers, yielding large spatial separations [5,46]. In particular, we are currently evaluating [47] what are the contraints on the model of Ref. [11] imposed by the experimental results published very recently in Ref.…”