Analysis of a new decoherence channel reveals nano-object interferometry is possible

Quantifying the quantum nature of gravity, which combines quantum mechanics with general relativity, is a century-old dream that continues to elude researchers. Specialized interferometers may provide insight into aspects of this problem, such as the graviton and gravitationally induced collapse.

Henkel and Folman examined the coherent splitting of a nano-object using a full-loop Stern-Gerlach interferometer. The interferometer uses magnetic gradients rather than traditional light pulses to generate a spatial superposition.

The observable was the spin of a single impurity embedded in the particle. The spin, when interacting with the pulsed magnetic gradient, generates a force on the particle. This method may allow for superpositions above the current limit of 2000 atoms.

“An interference of such a massive object, built from many atoms, would also enable the testing of different exotic theories that go beyond the standard model of physics,” said author Carsten Henkel. “Realizing such an experiment is extremely important.”

The researchers calculated the decoherence channel produced by internal phonon sound waves by considering various parameters including the onset of the magnetic field, non-zero temperatures, and increased masses.

“The channel of internal phonons has never been calculated before. It is a completely new take on decoherence,” said Henkel.

The results indicate that phonon dynamics are not inhibiting factors for a large range of parameters in nano-object Stern-Gerlach interferometer. However, phonons do constitute a fundamental limit on the splitting of larger macroscopic objects if the applied force induces phonons.

More opportunities for research exist to determine the collective interaction of larger objects with different fields.

Source: “Internal decoherence in nano-object interferometry due to phonons,” by C. Henkel and R. Folman, AVS Quantum Science (2022). The article can be accessed at https://doi.org/10.1116/5.0080503 .

This paper is part of the Celebrating Sir Roger Penrose’s Nobel Prize collection. Learn more here .