Hidden Dissipation and Irreversibility in Maxwell’s Demon

Maxwell’s demon is an entity in a 150-year-old thought experiment that paradoxically appears to violate the second law of thermodynamics by reducing entropy without doing work. It has increasingly practical implications as advances in nanomachinery produce devices that push the thermodynamic limits imposed by the second law. A well-known explanation claiming that information erasure restores second law compliance fails to resolve the paradox because it assumes the second law a priori, and does not predict irreversibility. Instead, a purely mechanical resolution that does not require information theory is presented. The transport fluxes of mass, momentum, and energy involved in the demon’s operation are analyzed and show that they imply “hidden” external work and dissipation. Computing the dissipation leads to a new lower bound on entropy production by the demon. It is strictly positive in all nontrivial cases, providing a more stringent limit than the second law and implying intrinsic thermodynamic irreversibility. The thermodynamic irreversibility is linked with mechanical irreversibility resulting from the spatial asymmetry of the demon’s speed selection criteria, indicating one mechanism by which macroscopic irreversibility may emerge from microscopic dynamics.

The Search for μ+ → e+γ with 10–14 Sensitivity: The Upgrade of the MEG Experiment

The MEG experiment took data at the Paul Scherrer Institute in the years 2009–2013 to test the violation of the lepton flavor conservation law, which originates from an accidental symmetry that the Standard Model of elementary particle physics has, and published the most stringent limit on the charged lepton flavor violating decay μ+→e+γ: BR(μ+→e+γ) <4.2×10−13 at 90% confidence level. The MEG detector has been upgraded in order to reach a sensitivity of 6×10−14. The basic principle of MEG II is to achieve the highest possible sensitivity using the full muon beam intensity at the Paul Scherrer Institute (7×107 muons/s) with an upgraded detector. The main improvements are better rate capability of all sub-detectors and improved resolutions while keeping the same detector concept. In this paper, we present the current status of the preparation, integration and commissioning of the MEG II detector in the recent engineering runs.

Insight into primordial magnetic fields from 21-cm line observation with EDGES experiment

The recent observation of the 21-cm global absorption signal by EDGES suggests that the intergalactic medium (IGM) gas has been cooler than the cosmic microwave background during 15 ≲ z ≲ 20. This result can provide a strong constraint on heating sources for the IGM gas at these redshifts. In this paper we study the constraint on the primordial magnetic fields (PMFs) by the EDGES result. The PMFs can heat the IGM gas through their energy dissipation due to the magnetohydrodynamic effects. By numerically solving the thermal evolution of the IGM gas with the PMFs, we find that the EDGES result gives a stringent limit on the PMFs as B1 Mpc ≲ 10−10 G.

Result on the Neutrinoless Double Beta Decay Search of 82Se with the CUPID-0 Experiment

CUPID-0 is the first large array of scintillating Zn 82 Se cryogenic calorimeters (bolometers) implementing particle identification for the search of the neutrinoless double beta decay (0 ν β β ). The detector consists of 24 enriched Zn 82 Se bolometers for a total 82 Se mass of 5.28 kg and it has been taking data in the underground LNGS (Italy) since March 2017. In this article we show how the dual read-out provides a powerful tool for the α particles rejection. The simultaneous use of the heat and light information allows us to reduce the background down to (3.2 − 1.1 + 1.3 )×10 − 3 counts/(keV kg year), an unprecedented level for cryogenic calorimeters. In a total exposure of 5.46 kg year Zn 82 Se we set the most stringent limit on the 0 ν β β decay 82 Se half-life T 1 / 2 0 ν > 4.0 × 10 24 year at 90% C.I.

An Updated Constraint on Variations of the Fine-Structure Constant Using Wavelengths of Fe II Absorption Line Multiplets

A new stringent limit relating to the variation of the fine-structure constant (α= e2/4πε0ℏc) has been extracted from Ritz wavelengths of 27 quasi_stellar object (QSO) absorption spectra lines of Fe II. The calculation was combined with laboratory wavelengths and QSO spectra to obtain the result ∆α/α=(0.027±0.832)×10-6. This result suggests how dedicated astrophysical estimations can improve these limits in the future and can also constrain space_time variations.