Primordial Black Holes from Sound Speed Resonance during Inflation

We report on a novel phenomenon of the resonance effect of primordial density perturbations arisen from a sound speed parameter with an oscillatory behavior, which can generically lead to the formation of primordial black holes in the early Universe. For a general inflaton field, it can seed primordial density fluctuations and their propagation is governed by a parameter of sound speed square. Once if this parameter achieves an oscillatory feature for a while during inflation, a significant non-perturbative resonance effect on the inflaton field fluctuations takes place around a critical length scale, which results in significant peaks in the primordial power spectrum. By virtue of this robust mechanism, primordial black holes with specific mass function can be produced with a sufficient abundance for dark matter in sizable parameter ranges.Comment: 6 pages, 4 figures; v2: figures replotted with corrections, analysis extended, version accepted by Phys.Rev.Let

Diaqua­bis­[5-(1-oxidopyridin-1-ium-2-yl)-1,2,3,4-tetrazolido]manganese(II) di­hydrate

In the title compound, [Mn(C6H4N5O)2(H2O)2]·2H2O, the MnII ion is situated on an inversion centre and is coordinated by the O and N atoms of two bis-chelating 5-(2-pyridyl-1-oxide)tetra­zolate ligands and two O atoms of two water mol­ecules in a distorted octa­hedral geometry. All the water H atoms are involved in O—H⋯N and O—H⋯O hydrogen bonds with uncoordinated water O atoms and tetra­zole N atoms, which link the mol­ecules into a three-dimensional network

Efficient scheme for three-photon Greenberger-Horne-Zeilinger state generation

We propose an efficient scheme for the generation of three-photon Greenberger-Horne-Zeilinger (GHZ) state with linear optics and postselection. Several devices are designed and a two-mode quantum nondemolition (QND) detection is introduced to obtain the desired state. It is worth noting that the states which have entanglement in both polarization and spatial degrees of freedom are created in one of the designed setups. The method described in the present scheme can create a large number of three-photon GHZ states in principle. We also discuss an approach to generate the desired GHZ state in the presence of channel noise.Comment: 7pages, 3 figure

A Continuous Dual-Axis Atomic Interferometric Inertial Sensor

We present an interferometric inertial sensor that utilizes two counter-propagating atomic beams with transverse two-dimensional cooling. By employing three parallel and spatially aligned Raman laser beams for Doppler-sensitive Raman transitions, we successfully generate inertia-sensitive Mach-Zehnder interference fringes with an interrogation length of $2L=54\,\rm{cm}$. The measured rotation and acceleration sensitivities are $0.25\,(\mu\rm{rad/s})/\sqrt{Hz}$ and $0.12\,\rm{m}\textit{g}/\rm{\sqrt{Hz}}$, respectively. The sensor's capability to measure rotation and acceleration simultaneously in dynamic environments is validated through comparative analysis with classical sensors under force oscillation in different directions. Additionally, we conduct experiments on a turntable to calibrate the gyroscope's scaling factor and address nonlinearity.Comment: 8 pages, 4 figure

Sound speed resonance of the stochastic gravitational wave background

We propose a novel mechanism to test time variation of the propagation speed of gravitational waves (GWs) in light of GWs astronomy. As the stochastic GWs experience the whole history of cosmic expansion, they encode potential observational evidence of such variation. We report that, one feature of a varying GWs speed is that the energy spectrum of GWs will present resonantly-enhanced peaks if the GWs speed oscillates in time at high-energy scales. Such oscillatory behaviour arises in a wide class of modified gravity theories. The amplitude of these peaks can be at reach by current and forthcoming GWs instruments, hence making the underlying theories falsifiable. This mechanism reveals that probing the variation of GWs speed can be a promising way to search for new physics beyond general relativity.Comment: 6 pages, 2 figure