Ultralight axion-like particles are well-motivated dark matter candidates introduced by theories beyond the standard model of particle physics. However, directly constraining their parameter space ...with laboratory experiments usually yields weaker limits than indirect approaches relying on astrophysical observations. Here we report the search for axion-like particles with a quantum sensor in the mass range of 8.3–744.0 feV. The sensor makes use of hyperpolarized long-lived nuclear spins as a pre-amplifier that effectively enhances a coherently oscillating axion-like dark matter field by a factor of more than 100. Using these spin-based amplifiers, we achieve an ultrahigh magnetic sensitivity of 18 fT Hz–(1/2), which exceeds the performance of state-of-the-art nuclear spin magnetometers. Our experiment constrains the parameter space describing the coupling of axion-like particles to nucleons over the aforementioned mass range, namely, at 67.5 feV reaching 2.9 × 10−9 GeV−1, improving on previous laboratory constraints by at least five orders of magnitude. Our measurements also constrain the quadratic interaction between axion-like particles and nucleons as well as interactions between dark photons and nucleons, exceeding bounds from astrophysical observations.A search for axion-like dark matter with a quantum sensor that enhances potential signals is reported. This work constrains the parameter space of different interactions between nucleons and axion-like particles and between nucleons and dark photons.
Abstract
The superradiant phase transition in thermal equilibrium is a fundamental concept bridging statistical physics and electrodynamics, which has never been observed in real physical systems ...since the first proposal in the 1970s. The existence of this phase transition in cavity quantum electrodynamics systems is still subject of ongoing debates due to the no-go theorem induced by the so-called
A
2
term. Moreover, experimental conditions to study this phase transition are hard to achieve with current accessible technology. Based on the platform of nuclear magnetic resonance, here we experimentally simulate the occurrence of an equilibrium superradiant phase transition beyond no-go theorem by introducing the antisqueezing effect. The mechanism relies on that the antisqueezing effect recovers the singularity of the ground state via exponentially enhancing the zero point fluctuation of system. The strongly entangled and squeezed Schrödinger cat states of spins are achieved experimentally in the superradiant phase, which may play an important role in fundamental tests of quantum theory and implementations of quantum metrology.
A typical soil shrinkage curve is S‐shaped and composed of four phases termed structural, proportional, residual, and zero shrinkage. However, many studies have not found all four soil shrinkage ...phases despite investigating the full spectrum of soil moisture content. The objectives of this paper were to determine different soil shrinkage types based on the presence of shrinkage phases and to define relationships between the parameters of different shrinkage types and soil properties. A total of 270 sets of shrinkage data were collected from published (N = 245) and our unpublished work (N = 25), covering a wide range of soil types, sample sizes, and measurement methods. According to the presence of different shrinkage phases, six types of soil shrinkage curves were classified using the shrinkage model proposed by Peng and Horn (2005). Soil shrinkage types generally depended on soil structure, but not on the measurement method. The coefficient of linear extensibility (COLE) had a positive relation with saturated soil bulk density (r = 0.50, P < 0.001), clay content (r = 0.20, P < 0.05), and soil organic carbon (SOC) content (r = 0.46, P < 0.001). This paper is the first to propose six soil shrinkage types that will improve our understanding of the relationship between soil structure and soil water content.
Aims
Crop genotypes may respond differently to various physical soil conditions. The objective of this study was to investigate the responses of the root architectures of two maize cultivars ...(Zhengdan958 and Denghai605) to various soil compaction and moisture conditions.
Methods
Two compaction levels (1.3 g cm
− 3
and 1.6 g cm
− 3
) and two moisture conditions (60% and 80% field capacity) were investigated to determine their impact on root growth. The root architectures of maize seedlings were assessed via X-ray computed tomography (CT). Soil penetration resistance, above-ground biomass and root biomass values were also determined.
Results
Soil moisture had significant effects on root biomass, above-ground biomass, the ratio of root biomass to above-ground biomass, and all root traits except for root volume. Soil compaction reduced root surface area and total root length of Zhengdan958 at 80% field capacity but not at 60% field capacity. However, soil compaction had little impact on root traits of Denghai605 at both moisture levels. Zhengdan958 had larger root volume, total root length, root diameter, root biomass and above-ground biomass than Denghai605 under noncompacted conditions. The ratio of root biomass to above-ground biomass was greater for Zhengdan958 than Denghai605 at the noncompacted and 60% field capacity conditions.
Conclusions
High moisture content has negative effects on root traits in compacted soil. The response of root architectures to soil compaction was more sensitive in Zhengdan958 than Denghai605. Zhengdan958 showed greater growth performance than Denghai605 under noncompacted conditions, and the drought tolerance of Zhengdan958 was greater than that of Denghai605.
The idea of the out-of-time-order correlator (OTOC) has recently emerged in the study of both condensed matter systems and gravitational systems. It not only plays a key role in investigating the ...holographic duality between a strongly interacting quantum system and a gravitational system, it also diagnoses the chaotic behavior of many-body quantum systems and characterizes information scrambling. Based on OTOCs, three different concepts—quantum chaos, holographic duality, and information scrambling—are found to be intimately related to each other. Despite its theoretical importance, the experimental measurement of the OTOC is quite challenging, and thus far there is no experimental measurement of the OTOC for local operators. Here, we report the measurement of OTOCs of local operators for an Ising spin chain on a nuclear magnetic resonance quantum simulator. We observe that the OTOC behaves differently in the integrable and nonintegrable cases. Based on the recent discovered relationship between OTOCs and the growth of entanglement entropy in the many-body system, we extract the entanglement entropy from the measured OTOCs, which clearly shows that the information entropy oscillates in time for integrable models and scrambles for nonintgrable models. With the measured OTOCs, we also obtain the experimental result of the butterfly velocity, which measures the speed of correlation propagation. Our experiment paves a way for experimentally studying quantum chaos, holographic duality, and information scrambling in many-body quantum systems with quantum simulators.
Long-term fertilization practices generally improve soil aggregation through associated increases in organic matter over time. However, the influence of organic versus inorganic fertilization on ...aggregate structures may be quite different. In this paper, we aimed to quantify the three-dimensional (3D) microstructure of soil aggregates as influenced by different long-term fertilization practices. Soil aggregates with diameters of approximately 5mm were collected from an Ultisol with a long-term fertilization trial established in 1986. The treatments were no fertilizer (CK), chemical fertilizer (NPK), and chemical fertilizer plus organic manure (NPK+OM). The aggregate microstructure was determined with synchrotron based X-ray micro-computed tomography (SR-μCT) and digital image analysis techniques. Mean corn yields and soil organic carbon were the highest in NPK+OM, followed by NPK and then by CK. Aggregate stability was highest in NPK+OM, and lowest in NPK. The number of pores, number of pore throats, and number of paths between adjacent nodal pores were all significantly decreased by the NPK+OM treatment relative to the NPK and CK treatments. However, microstructural pore properties were mostly not different between NPK and CK treatments. This study demonstrates that organic fertilization can improve soil aggregation, while inorganic fertilization is ineffective, even after 25years. The different mechanisms by which organic and inorganic fertilization practices influence soil aggregation deserve further investigation.
► Organic and inorganic fertilization leads to different aggregate microstructure. ► Application of NPK+OM improved soil aggregation, stability, SOM, and crop yield. ► Synchrotron μ-CT and shape parameters revealed different aggregate structure.
Quantum metrology plays a fundamental role in many scientific areas. However, the complexity of engineering entangled probes and the external noise raise technological barriers for realizing the ...expected precision of the to-be-estimated parameter with given resources. Here, we address this problem by introducing adjustable controls into the encoding process and then utilizing a hybrid quantum-classical approach to automatically optimize the controls online. Our scheme does not require any complex or intractable off-line design, and it can inherently correct certain unitary errors during the learning procedure. We also report the first experimental demonstration of this promising scheme for the task of finding optimal probes for frequency estimation on a nuclear magnetic resonance (NMR) processor. The proposed scheme paves the way to experimentally auto-search optimal protocol for improving the metrology precision.
Reports regarding the effects of long-term organic and inorganic fertilization on the quantity and quality of soil organic carbon (SOC), particularly in Vertisols, are scarce. In this study, we ...combined SOC physical fractionation with
C NMR spectroscopy technology to investigate the effect of 34 years of continuous fertilization on the SOC physical fractions and its chemical composition of 0-20 cm soil layer in a Vertisol. This study consisted of six treatments: no fertilization (control), chemical nitrogen, phosphorus and potassium fertilizers (NPK), low and high amounts of straw with chemical fertilizers (NPKLS and NPKHS), and pig or cattle manure with chemical fertilizers (NPKPM and NPKCM). Over 34 years of continuous fertilization, the SOC sequestration rate was from 0.08 Mg C ha
yr
in the control treatment to 0.66 Mg C ha
yr
in the NPKCM treatment, which was linearly related with the C input (P < 0.01). Of the five SOC physical fractions, two silt plus clay fractions (S + C_M, S + C_mM) dominated 74-92% of SOC, while three POM fractions (cPOM fPOM and iPOM) were only 8-26%. The two manure application treatments significantly increased all the SOC physical fractions except for the silt plus clay fraction within macroaggregates (S + C_M) compared with NPK treatment (P < 0.05), which was dependent on the larger amount of C input. Also, the two manure application treatments increased the levels of alkyl C and aromatic C but decreased O-alkyl C (P < 0.05), whereas the straw application (NPKLS and NPKHS) had no impact on the C functional groups (P > 0.05). Overall, the combination of animal manure with inorganic fertilization could enhance the SOC sequestration and alter its quantity and quality in Vertisols.
•Biopore- and matrix-dominated samples were isolated to estimate macropore flow.•Biopores and percolating biopores were separated for biopore-dominated samples.•Characteristics of percolating ...biopores were better at predicting water or air flow.•The mean diameter of the limiting layer (MDLL) was the best predictor.
The different types of soil macropores (e.g., biopores and non-biopores) vary in the conductivity of water or air due to the difference in the 3D pore characteristics. The objectives of this study were to reveal which types of macropores and which macropore characteristics played the most important roles in regulating water or air flow. Intact soil columns sampled from the subsoil of a long-term fertilization experiment were scanned by medical X-ray computed tomography (CT), and subsequently, saturated hydraulic conductivity (Ks) and air permeability at −12 cm water potential (Ka12) were measured. The 3D characteristics of macropores were then analyzed with image analysis. The biopores and the percolating biopores that connected the top and the bottom of a soil column were separated for the biopore-dominated samples (with percolating biopores) and their 3D characteristics were also quantified. Our results showed that the mean macropore diameter of the limiting layer (MDLL) presented the best relationships with Ks and Ka12 compared with the other macropore characteristics for all the samples. The biopores and percolating biopores contributed 27.8–74.5% and 3.26–64.4% of the volume of total macropores, respectively, for the biopore-dominated samples. The hydraulic radius, mean diameter, compactness, global and local connectivities, and MDLL of biopores, especially those of percolating biopores, were generally larger than those of total macropores. The global connectivity (Γ) of biopores performed very well for estimating Ks and Ka12. The MDLL of percolating biopores could predict Ks much better than the MDLL of biopores and total macropores. Moreover, the performance of MDLL for estimating Ka12 was as good as the MDLL of biopores but was much better than the MDLL of total macropores. The findings of this study reveal that the MDLL is a more useful parameter in estimating saturated hydraulic conductivity and air permeability at low water potential than the other CT-derived pore characteristics.
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