Multiscale Cluster Interference Experiment, MUSCLE

The experiment MUSCLE builds conceptually on the near-field interferometers developed throughout the last two decades in our group, but it substantially expands on this by 

• A cold metal cluster source, based on aggregation of a thermal sodium vapor in a cryogenic buffer gas. This allows covering a wide range of high masses and high photosensitivity.
• Deep ultraviolet photodepletion gratings with up to 1W of laser power at 266 nm, to form absorptive and phase gratings with periods of 133 nm.
• Refined mass spectrometer schemes to identify the charge state of even massive clusters.
• The total interferometer length is 2 m.

The experiment allowed us to push quantum macroscopicity to a new record value and to explore future applications even in Moiré mode: 

• S. Pedalino, B.E. Ramirez, R. Ferstl, K. Hornberger, M. Arndt, S. Gerlich,
  Probing quantum mechanics with nanoparticle matter-wave interferometry,
  Nature 649, 8098 (2026), doi:10.1038/s41586-025-09917-9 .
• S. Pedalino, R. Ferstl, B.E. Ramírez-Galindo, S. Sindelar, S. Gerlich, M. Arndt,
  De Broglie and moiré metrology: From atoms to massive metal clusters, 
  AVS Quantum Science 8, 013201 (2026), doi:10.1116/5.0301389.