The control of many-body quantum dynamics in complex systems is a key challenge in the quest to reliably produce and manipulate large-scale quantum entangled states. Recently, quench experiments in ...Rydberg atom arrays Bluvstein et al. Science 371, 1355 (2021) demonstrated that coherent revivals associated with quantum many-body scars can be stabilized by periodic driving, generating stable subharmonic responses over a wide parameter regime. We analyze a simple, related model where these phenomena originate from spatiotemporal ordering in an effective Floquet unitary, corresponding to discrete time-crystalline behavior in a prethermal regime. Unlike conventional discrete time crystals, the subharmonic response exists only for Néel-like initial states, associated with quantum scars. We predict robustness to perturbations and identify emergent timescales that could be observed in future experiments. Our results suggest a route to controlling entanglement in interacting quantum systems by combining periodic driving with many-body scars.
Spatial sensing with hydrogenThe coupling of coherent quantum systems to the surrounding environment can be used to create highly sensitive sensors, but many surface-based implementations, such as ...nitrogen vacancies in diamond, have limited spatial resolution. Wang et al. created a quantum sensor with high spatial sensitivity by using the electric field from a scanning tunneling microscope tip to confine a hydrogen molecule on copper nitride islands grown on a copper surface. Femtosecond-pulse terahertz spectroscopy was used to follow the coherence of the two-level system created by different adsorption geometries. The temporal oscillations and decoherence in the superposition state showed spatial variations at the sub-angstrom scale. —PDS
Abstract
In recent years our understanding of the dense matter equation of state (EOS) of neutron stars has significantly improved by analyzing multimessenger data from radio/X-ray pulsars, ...gravitational wave events, and from nuclear physics constraints. Here we study the additional impact on the EOS from the jointly estimated mass and radius of PSR J0740+6620, presented in Riley et al. by analyzing a combined data set from X-ray telescopes NICER and XMM-Newton. We employ two different high-density EOS parameterizations: a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS). At nuclear densities these are connected to microscopic calculations of neutron matter based on chiral effective field theory (EFT) interactions. In addition to the new NICER data for this heavy neutron star, we separately study constraints from the radio timing mass measurement of PSR J0740+6620, the gravitational wave events of binary neutron stars GW190425 and GW170817, and for the latter the associated kilonova AT2017gfo. By combining all these, and the NICER mass–radius estimate of PSR J0030+0451, we find the radius of a 1.4
M
⊙
neutron star to be constrained to the 95% credible ranges
12.33
−
0.81
+
0.76
km
(PP model) and
12.18
−
0.79
+
0.56
km
(CS model). In addition, we explore different chiral EFT calculations and show that the new NICER results provide tight constraints for the pressure of neutron star matter at around twice saturation density, which shows the power of these observations to constrain dense matter interactions at intermediate densities.
Most existing dimensionality reduction and clustering packages for single-cell RNA-seq (scRNA-seq) data deal with dropouts by heavy modeling and computational machinery. Here, we introduce CIDR ...(Clustering through Imputation and Dimensionality Reduction), an ultrafast algorithm that uses a novel yet very simple implicit imputation approach to alleviate the impact of dropouts in scRNA-seq data in a principled manner. Using a range of simulated and real data, we show that CIDR improves the standard principal component analysis and outperforms the state-of-the-art methods, namely t-SNE, ZIFA, and RaceID, in terms of clustering accuracy. CIDR typically completes within seconds when processing a data set of hundreds of cells and minutes for a data set of thousands of cells. CIDR can be downloaded at https://github.com/VCCRI/CIDR .
Abstract
We analyse observations of eight quiescent low-mass X-ray binaries in globular clusters and combine them to determine the neutron star mass–radius curve and the equation of state of dense ...matter. We determine the effect that several uncertainties may have on our results, including uncertainties in the distance, the atmosphere composition, the neutron star maximum mass, the neutron star mass distribution, the possible presence of a hotspot on the neutron star surface, and the prior choice for the equation of state of dense matter. The distance uncertainty is implemented in a new Gaussian blurring method that can be directly applied to the probability distribution over mass and radius. We find that the radius of a 1.4 solar mass neutron star is most likely from 10 to 14 km and that tighter constraints are only possible with stronger assumptions about the nature of the neutron stars, the systematics of the observations, or the nature of dense matter. Strong phase transitions in the equation of state are preferred, and in this case, the radius is likely smaller than 12 km. However, radii larger than 12 km are preferred if the neutron stars have uneven temperature distributions.
Abstract
PSR J0740+6620 has a gravitational mass of 2.08 ± 0.07
M
⊙
, which is the highest reliably determined mass of any neutron star. As a result, a measurement of its radius will provide unique ...insight into the properties of neutron star core matter at high densities. Here we report a radius measurement based on fits of rotating hot spot patterns to Neutron Star Interior Composition Explorer (NICER) and X-ray Multi-Mirror (XMM-Newton) X-ray observations. We find that the equatorial circumferential radius of PSR J0740+6620 is
13.7
−
1.5
+
2.6
km (68%). We apply our measurement, combined with the previous NICER mass and radius measurement of PSR J0030+0451, the masses of two other ∼2
M
⊙
pulsars, and the tidal deformability constraints from two gravitational wave events, to three different frameworks for equation-of-state modeling, and find consistent results at ∼1.5–5 times nuclear saturation density. For a given framework, when all measurements are included, the radius of a 1.4
M
⊙
neutron star is known to ±4% (68% credibility) and the radius of a 2.08
M
⊙
neutron star is known to ±5%. The full radius range that spans the ±1
σ
credible intervals of all the radius estimates in the three frameworks is 12.45 ± 0.65 km for a 1.4
M
⊙
neutron star and 12.35 ± 0.75 km for a 2.08
M
⊙
neutron star.
All-inorganic CsPbI
perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots ...materials and the various exciting properties that perovskites have to offer. These quantum dot devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies. We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high-performance and flexible optoelectronic devices using nanoscale grains as an advantage. Specifically, we develop a hybrid interfacial architecture consisting of CsPbI
quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion. The champion CsPbI
quantum dot solar cell has an efficiency of 15.1% (stabilized power output of 14.61%), which is among the highest report to date. Building on this strategy, we further demonstrate a highest efficiency of 12.3% in flexible quantum dot photovoltaics.
The control of nonequilibrium quantum dynamics in many-body systems is challenging because interactions typically lead to thermalization and a chaotic spreading throughout Hilbert space. We ...investigate nonequilibrium dynamics after rapid quenches in a many-body system composed of 3 to 200 strongly interacting qubits in one and two spatial dimensions. Using a programmable quantum simulator based on Rydberg atom arrays, we show that coherent revivals associated with so-called quantum many-body scars can be stabilized by periodic driving, which generates a robust subharmonic response akin to discrete time-crystalline order. We map Hilbert space dynamics, geometry dependence, phase diagrams, and system-size dependence of this emergent phenomenon, demonstrating new ways to steer complex dynamics in many-body systems and enabling potential applications in quantum information science.
Novel thin-film-composite reverse osmosis membranes were synthesized successfully for seawater desalination by incorporating the hydrophilic additive, o-aminobenzoic acid–triethylamine (o-ABA–TEA) ...salt, into the aqueous m-phenylenediamine (MPD) solution to react with trimesoyl chloride (TMC) in the organic solution during the interfacial polymerization on a nanoporous polysulfone support. The membrane synthesis conditions, including o-ABA–TEA salt concentration, isopropanol (IPA) concentration, additional amine drying time, and hydrocarbon removal time, were optimized by characterizing membrane performances using synthetic 3.28wt% NaCl solution under seawater desalination conditions at 800psi (5.52MPa) and 25°C. The synthesized membranes showed a very high flux of 1.81m3/m2/day (44.4gallons/ft2/day (gfd)) and a salt rejection of 99.41%. The improvement of membrane hydrophilicity was confirmed by comparing the contact angles of the membranes synthesized with and without the hydrophilic additive. The high-flux membrane was further tested using seawater from Port Hueneme, CA and exhibited a very good and stable desalination performance for 30 days. The fouling-resistant properties of the membranes synthesized with and without the hydrophilic additive were evaluated by using sodium alginate, a common contaminant derived from seaweed, as the model foulant. The membrane synthesized with hydrophilic additive showed significantly smaller water flux decline. The surface morphologies of the membranes were analyzed using atomic force microscopy (AFM). The results showed a smoother membrane surface for the membrane incorporated with the hydrophilic additive.
•High-flux fouling-resistant membrane was synthesized for seawater desalination.•The resultant membrane showed a very high water flux of 1.81m3/m2/day.•Desalination performance was evaluated and analyzed using real seawater.•The synthesized membrane demonstrated good stability during a 30-day test.•Membrane fouling resistance to sodium alginate was significantly improved.
PDF
