Neutrino oscillations at the highest energies and longest baselines can
be used to study the structure of spacetime and test the fundamental
principles of quantum mechanics. If the metric of spacetime has a quantum
mechanical description, its fluctuations at the Planck scale are expected
to introduce non-unitary effects that are inconsistent with the standard
unitary time evolution of quantum mechanics. Neutrinos interacting with
such fluctuations would lose their quantum coherence, deviating from
the expected oscillatory flavour composition at long distances and high
energies. Here we use atmospheric neutrinos detected by the IceCube South
Pole Neutrino Observatory in the energy range of 0.5–10.0 TeV to search for
coherence loss in neutrino propagation. We find no evidence of anomalous
neutrino decoherence and determine limits on neutrino–quantum
gravity interactions. The constraint on the effective decoherence strength
parameter within an energy-independent decoherence model improves
on previous limits by a factor of 30. For decoherence effects scaling as E2 ,
our limits are advanced by more than six orders of magnitude beyond past
measurements compared with the state of the art.
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Approaching the motional ground state of a 10-kg object
The motion of a mechanical object, even a human-sized object, should be governed by the rules of quantum mechanics. Coaxing them into a quantum state is, however, difficult because the thermal environment masks any quantum signature of the object’s motion. The thermal environment also masks the effects of proposed modifications of quantum mechanics at large mass scales. We prepared the center-of-mass motion of a 10-kilogram mechanical oscillator in a state with an average phonon occupation of 10.8. The reduction in temperature, from room temperature to 77 nanokelvin, is commensurate with an 11 orders-of-magnitude suppression of quantum back-action by feedback and a 13 orders-of-magnitude increase in the mass of an object prepared close to its motional ground state. Our approach will enable the possibility of probing gravity on massive quantum systems.
more » « less- PAR ID:
- 10250626
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- American Association for the Advancement of Science (AAAS)
- Date Published:
- Journal Name:
- Science
- Volume:
- 372
- Issue:
- 6548
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- p. 1333-1336
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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