4 research outputs found
Classical many-body time crystals
Discrete time crystals are a many-body state of matter where the extensive
system's dynamics are slower than the forces acting on it. Nowadays, there is a
growing debate regarding the specific properties required to demonstrate such a
many-body state, alongside several experimental realizations. In this work, we
provide a simple and pedagogical framework by which to obtain many-body time
crystals using parametrically coupled resonators. In our analysis, we use
classical period-doubling bifurcation theory and present a clear distinction
between single-mode time-translation symmetry breaking and a situation where an
extensive number of degrees of freedom undergo the transition. We
experimentally demonstrate this paradigm using coupled mechanical oscillators,
thus providing a clear route for time crystals realizations in real materials.Comment: 23 pages, 5 figures, comments are welcom
Comparing black-carbon- and aerosol-absorption-measuring instruments
We report on an inter-comparison of black-carbon- and aerosol-absorption-measuring instruments with laboratory-generated soot particles coated with controlled amounts of secondary organic matter (SOM). The aerosol generation setup consisted of a miniCAST 5201 Type BC burner for the generation of soot particles and a new automated oxidation flow reactor based on the micro smog chamber (MSC) for the generation of SOM from the ozonolysis of α-pinene. A series of test aerosols was generated with elemental to total carbon (EC TC) mass fraction ranging from about 90 % down to 10 % and single-scattering albedo (SSA at 637 nm) from almost 0 to about 0.7. A dual-spot Aethalometer AE33, a photoacoustic extinctiometer (PAX, 870 nm), a multi-angle absorption photometer (MAAP), a prototype photoacoustic instrument, and two prototype photo-thermal interferometers (PTAAM-2λ and MSPTI) were exposed to the test aerosols in parallel. Significant deviations in the response of the instruments were observed depending on the amount of secondary organic coating. We believe that the setup and methodology described in this study can easily be standardised and provide a straightforward and reproducible procedure for the inter-comparison and characterisation of both filter-based and in situ black-carbon-measuring (BC-measuring) instruments based on realistic test aerosols