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1.
Heliyon ; 10(16): e34407, 2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-39253236

RESUMO

In the realm of modern healthcare, Electronic Health Records EHR serve as invaluable assets, yet they also pose significant security challenges. The absence of EHR access auditing mechanisms, which includes the EHR audit trails, results in accountability gaps and magnifies security vulnerabilities. This situation effectively paves the way for unauthorized data alterations to occur without detection or consequences. Inadequate EHR compliance auditing procedures, particularly in verifying and validating access control policies, expose healthcare organizations to risks such as data breaches, and unauthorized data usage. These vulnerabilities result from unchecked unauthorized access activities. Additionally, the absence of EHR audit logs complicates investigations, weakens proactive security measures, and raises concerns to put healthcare institutions at risk. This study addresses the pressing need for robust EHR auditing systems designed to scrutinize access to EHR data, encompassing who accesses it, when, and for what purpose. Our research delves into the complex field of EHR auditing, which includes establishing an immutable audit trail to enhance data security through blockchain technology. We also integrate Purpose-Based Access Control (PBAC) alongside smart contracts to strengthen compliance auditing by validating access legitimacy and reducing unauthorized entries. Our contributions encompass the creation of audit trail of EHR access, compliance auditing via PBAC policy verification, the generation of audit logs, and the derivation of data-driven insights, fortifying EHR access security.

2.
Int J Biol Macromol ; 278(Pt 2): 134657, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39147346

RESUMO

This research addresses the need for enhanced biomaterials by investigating the influence of the NCO/OH ratio on sodium alginate-based polyurethane elastomers(Al-PUEs), offering novel insights into their structural, thermal, mechanical and swelling behavior. Al-PUEs were prepared by blending the chain extenders with key ingredients in a specific molar ratio using aliphatic HMDI and HTPB monomers. The chemical linkages, crystalline behavior, homogeneity, and surface morphology of PUEs were evaluated by FT-IR, XRD, SEM, and EDX analysis. Thermo-mechanical studies were performed using TGA, DSC and tensile testing. Swelling behavior and absorption analysis were analyzed in DMSO and water. The analysis indicated that the hydrophilicity and swelling behavior of the prepared PUEs were affected by the addition of sodium alginate content. The results exhibit the tailor-made network structure of Al-PUEs, resulting in better thermal stability, elasticity of materials via stress-strain behavior and marvelous characteristic features than traditional high-tech yields. Furthermore, the resulting Al-PUEs are potential candidates for biomedical implants.


Assuntos
Alginatos , Elastômeros , Isocianatos , Poliuretanos , Poliuretanos/química , Alginatos/química , Elastômeros/química , Isocianatos/química , Materiais Biocompatíveis/química , Resistência à Tração , Espectroscopia de Infravermelho com Transformada de Fourier , Teste de Materiais , Interações Hidrofóbicas e Hidrofílicas , Temperatura
3.
Phys Rev Lett ; 132(19): 190401, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38804950

RESUMO

Determining the statistics of work done on a quantum system while strongly coupled to a reservoir is a formidable task, requiring the calculation of the full eigenspectrum of the combined system and reservoir. Here, we show that this issue can be circumvented by using a polaron transformation that maps the system into a new frame where weak-coupling theory can be applied. Crucially, this polaron approach reproduces the Jarzynski fluctuation theorem, thus ensuring consistency with the laws of stochastic thermodynamics. We apply our formalism to a system driven across the Landau-Zener transition, where we identify clear signatures in the work distribution arising from a non-negligible coupling to the environment. Our results provide a new method for studying the stochastic thermodynamics of driven quantum systems beyond Markovian, weak-coupling regimes.

4.
RSC Adv ; 14(9): 5959-5974, 2024 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-38362070

RESUMO

Heavy metal contamination in water is a serious environmental issue due to the toxicity of metals like lead. This study developed zeolite and multi-walled carbon nanotube (MWCNT) incorporated polyacrylonitrile (PAN) nanofibers via needleless electrospinning and examined their potential for lead ion adsorption from aqueous solutions. The adsorption process was optimized using response surface methodology (RSM) and artificial neural network (ANN) modeling approaches. The adsorbent displayed efficient lead removal of 84.75% under optimum conditions (adsorbent dose (2.21 g), adsorption time (207 min), temperature (48 °C), and initial concentration (62 ppm)). Kinetic studies revealed that the adsorption followed pseudo-first-order kinetics governed by interparticle diffusion. Isotherm analysis indicated Langmuir monolayer adsorption with improved 5.90 mg g-1 capacity compared to pristine PAN nanofibers. Thermodynamic parameters suggested the adsorption was spontaneous and endothermic. This work demonstrates the promise of electrospun zeolite/MWCNT nanofibers as adsorbents for removing lead from wastewater.

5.
Crit Rev Anal Chem ; : 1-22, 2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38252119

RESUMO

Monitoring food safety is crucial and significantly impacts the ecosystem and human health. To adequately address food safety problems, a collaborative effort needed from government, industry, and consumers. Modern sensing technologies with outstanding performance are needed to meet the growing demands for quick and accurate food safety monitoring. Recently, emerging sensors for regulating food safety have been extensively explored. Along with the development in sensing technology, the metal-organic frameworks (MOF)-based sensors gained more attention due to their excellent sensing, catalytic, and adsorption properties. This review summarizes the current advancements and applications of MOFs-based sensors, including colorimetric, electrochemical, luminescent, surface-enhanced Raman scattering, and electrochemiluminescent sensors. and also focused on the applications of MOF-based sensors for the monitoring of toxins such as heavy metals, pesticide residues, mycotoxins, pathogens, and illegal food additives from food samples. Future trends, as well as current developments in MOF-based materials.

6.
Nat Commun ; 15(1): 485, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38212305

RESUMO

Single-molecule magnets are among the most promising platforms for achieving molecular-scale data storage and processing. Their magnetisation dynamics are determined by the interplay between electronic and vibrational degrees of freedom, which can couple coherently, leading to complex vibronic dynamics. Building on an ab initio description of the electronic and vibrational Hamiltonians, we formulate a non-perturbative vibronic model of the low-energy magnetic degrees of freedom in monometallic single-molecule magnets. Describing their low-temperature magnetism in terms of magnetic polarons, we are able to quantify the vibronic contribution to the quantum tunnelling of the magnetisation, a process that is commonly assumed to be independent of spin-phonon coupling. We find that the formation of magnetic polarons lowers the tunnelling probability in both amorphous and crystalline systems by stabilising the low-lying spin states. This work, thus, shows that spin-phonon coupling subtly influences magnetic relaxation in single-molecule magnets even at extremely low temperatures where no vibrational excitations are present.

7.
J Mater Sci ; 58(15): 6474-6515, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37065680

RESUMO

Organic pollutants in wastewater are the biggest problem facing the world today due to population growth, rapid increase in industrialization, urbanization, and technological advancement. There have been numerous attempts to use conventional wastewater treatment techniques to address the issue of worldwide water contamination. However, conventional wastewater treatment has a number of shortcomings, including high operating costs, low efficiency, difficult preparation, fast recombination of charge carriers, generation of secondary waste, and limited light absorption. Therefore, plasmonic-based heterojunction photocatalysts have attracted much attention as a promising method to reduce organic pollutant problems in water due to their excellent efficiency, low operating cost, ease of fabrication, and environmental friendliness. In addition, plasmonic-based heterojunction photocatalysts contain a local surface plasmon resonance that enhances the performance of photocatalysts by improving light absorption and separation of photoexcited charge carriers. This review summarizes the major plasmonic effects in photocatalysts, including hot electron, local field effect, and photothermal effect, and explains the plasmonic-based heterojunction photocatalysts with five junction systems for the degradation of pollutants. Recent work on the development of plasmonic-based heterojunction photocatalysts for the degradation of various organic pollutants in wastewater is also discussed. Lastly, the conclusions and challenges are briefly described and the direction of future development of heterojunction photocatalysts with plasmonic materials is explored. This review could serve as a guide for the understanding, investigation, and construction of plasmonic-based heterojunction photocatalysts for various organic pollutants degradation. Graphical abstract: Herein, the plasmonic effects in photocatalysts, such as hot electrons, local field effect, and photothermal effect, as well as the plasmonic-based heterojunction photocatalysts with five junction systems for the degradation of pollutants are explained. Recent work on plasmonic-based heterojunction photocatalysts for the degradation of various organic pollutants in wastewater such as dyes, pesticides, phenols, and antibiotics is discussed. Challenges and future developments are also described.

8.
Polymers (Basel) ; 15(6)2023 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-36987136

RESUMO

Nowadays, synthetic polymers are used in medical applications due to their special biodegradable, biocompatible, hydrophilic, and non-toxic properties. The materials, which can be used for wound dressing fabrication with controlled drug release profile, are the need of the time. The main aim of this study was to develop and characterize polyvinyl alcohol/polycaprolactone (PVA/PCL) fibres containing a model drug. A dope solution comprising PVA/PCL with the drug was extruded into a coagulation bath and became solidified. The developed PVA/PCL fibres were then rinsed and dried. These fibres were tested for Fourier transform infrared spectroscopy, linear density, topographic analysis, tensile properties, liquid absorption, swelling behaviour, degradation, antimicrobial activity, and drug release profile for improved and better healing of the wound. From the results, it was concluded that PVA/PCL fibres containing a model drug can be produced by using the wet spinning technique and have respectable tensile properties; adequate liquid absorption, swelling %, and degradation %; and good antimicrobial activity with the controlled drug release profile of the model drug for wound dressing applications.

9.
Membranes (Basel) ; 13(2)2023 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-36837659

RESUMO

Nanofiber-based facial masks have attracted the attention of modern cosmetic applications due to their controlled drug release, biocompatibility, and better efficiency. In this work, Azadirachta indica extract (AI) incorporated electrospun polyvinyl alcohol (PVA) nanofiber membrane was prepared to obtain a sustainable and hydrophilic facial mask. The electrospun AI incorporated PVA nanofiber membranes were characterized by scanning electron microscope, Ultraviolet-visible spectroscopy (UV-Vis) drug release, water absorption analysis, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, and antibacterial activity (qualitative and quantitative) at different PVA and AI concentrations. The optimized nanofiber of 376 ± 75 nm diameter was obtained at 8 wt/wt% PVA concentration and 100% AI extract. The AI nanoparticles of size range 50~250 nm in the extract were examined through a zeta sizer. The water absorption rate of ~660% and 17.24° water contact angle shows good hydrophilic nature and water absorbency of the nanofiber membrane. The UV-Vis also analyzed fast drug release of >70% in 5 min. The prepared membrane also exhibits 99.9% antibacterial activity against Staphylococcus aureus and has 79% antioxidant activity. Moreover, the membrane also had good mechanical properties (tensile strength 1.67 N, elongation 48%) and breathability (air permeability 15.24 mm/s). AI-incorporated nanofiber membrane can effectively be used for facial mask application.

10.
Membranes (Basel) ; 12(12)2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36557137

RESUMO

Sweat is a natural body excretion produced by skin glands, and the body cools itself by releasing salty sweat. Wetness in the underarms and feet for long durations causes itchiness and an unpleasant smell. Skin-friendly reusable sweat pads could be used to absorb sweat. Transportation of moisture and functionality is the current challenge that many researchers are working on. This study aims to develop a functional and breathable sweat pad with antimicrobial and quick drying performance. Three layered functional sweat pads (FSP) are prepared in which the inner layer is made of an optimized needle-punched coolmax/polypropylene nonwoven blend. This layer is then dipped in antimicrobial ZnO solution (2, 4, and 6 wt.%), and super absorbent polymer (SAP) is embedded, and this is called a functional nonwoven (FNW1) sheet. Electrospun nanofiber-based nanomembranes of polyamide-6 are optimized for bead-free fibers. They are used as a middle layer to enhance the pad's functionality, and the third layer is again made of needle-punched optimized coolmax/polypropylene nonwoven sheets. A simple nonwoven-based sweat pad (SSP) is also prepared for comparison purposes. Nonwoven sheets are optimized based on better comfort properties, including air/water vapor permeability and moisture management (MMT). Nonwoven webs having a higher proportion of coolmax show better air permeability and moisture transfer from the inner to the outer layer. Antimicrobial activity of the functional nonwoven layer showed 8 mm of bacterial growth, but SSP and FSP showed only 6 mm of growth against Staphylococcus aureus. FSP showed superior comfort and antibacterial properties. This study could be a footstone toward highly functional sweat pads with remarkable comfort properties.

11.
Membranes (Basel) ; 12(11)2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36422150

RESUMO

Textile-supported nanocomposite as a scaffold has been extensively used in the medical field, mainly to give support to weak or harmed tissues. However, there are some challenges in fabricating the nanofiber/textile composite, i.e., suitable porous structure with defined pore size, less skin contact area, biocompatibility, and availability of degradable materials. Herein, polyamide-6 (PA) nanofibers were synthesized using needleless electrospinning with the toothed wheel as a spinneret. The electrospinning process was optimized using different process and solution parameters. In the next phase, optimized PA nanofiber membranes of optimum fiber diameter with uniform distribution and thickness were used in making nanofiber membrane-textile composite. Different textile fabrics (woven, non-woven, knitted) were developed. The optimized nanofiber membranes were combined with non-woven, woven, and knitted fabrics to make fabric-supported nanocomposite. The nanofiber/fabric composites were compared with available market woven and knitted meshes for mechanical properties, morphology, structure, and chemical interaction analysis. It was found that the tear strength of the nanofiber/woven composite was three times higher than market woven mesh, and the nanofiber/knitted composite was 2.5 times higher than market knitted mesh. The developed composite structures with woven and knitted fabric exhibited improved bursting strength (613.1 and 751.1 Kpa), tensile strength (195.76 and 227.85 N), and puncture resistance (68.76 and 57.47 N), respectively, than market available meshes. All these properties showed that PA nanofibers/textile structures could be utilized as a composite with multifunctional properties.

12.
Curr Pharm Biotechnol ; 23(12): 1417-1435, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35352649

RESUMO

BACKGROUND: Wound healing is a complex process, and selecting an appropriate treatment is crucial and varies from one wound to another. Among injuries, burn wounds are more challenging to treat. Different dressings and scaffolds come into play when skin is injured. These scaffolds provide the optimum environment for wound healing. With the advancements in nanoengineering, scaffolds have been engineered to improve wound healing with lower fatality rates. OBJECTIVES: Nanoengineered systems have emerged as one of the most promising candidates for burn wound management. This review paper aims to provide an in-depth understanding of burn wounds and the role of nanoengineering in burn wound management. The advantages of nanoengineered scaffolds, their properties, and their proven effectiveness have been discussed. Nanoparticles and nanofibers-based nanoengineered therapeutic scaffolds provide optimum protection, infection management, and accelerated wound healing due to their unique characteristics. These scaffolds increase cell attachment and proliferation for desired results. RESULTS: The literature review suggested that the utilization of nanoengineered scaffolds has accelerated burn wound healing. Nanofibers provide better cell attachment and proliferation among different nanoengineered scaffolds because their 3D structure mimics the body's extracellular matrix. CONCLUSION: With these advanced nanoengineered scaffolds, better burn wound management is possible due to sustained drug delivery, better cell attachment, and an infection-free environment.


Assuntos
Queimaduras , Nanofibras , Queimaduras/tratamento farmacológico , Humanos , Nanofibras/química , Pele , Alicerces Teciduais/química , Cicatrização
13.
Curr Pharm Des ; 28(5): 368-379, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34587881

RESUMO

BACKGROUND: Nanotechnology is a tool being used intensely in the area of drug delivery systems in the biomedical field. Electrospraying is one of the nanotechnological methods, which is growing due to its importance in the development of nanoparticles comprising bioactive compounds. It is helpful in improving the efficacy, reducing side effects of active drug elements, and is useful in targeted drug delivery. When compared to other conventional methods like nanoprecipitation, emulsion diffusion, and double emulsification, electrospraying offers better advantages to produce micro/nanoparticles due to its simplicity, cost-effectiveness, and single-step process. OBJECTIVE: The aim of this paper is to highlight the use of electrosprayed nanoparticles for biomedical applications. METHODS: We conducted a literature review on the usage of natural and synthetic materials to produce nanoparticles, which can be used as a drug delivery system for medical purposes. RESULTS: We summarized a possible key role of electrosprayed nanoparticles in different therapeutic applications (tissue regeneration, cancer). CONCLUSION: The modest literature production denotes that further investigation is needed to assess and validate the promising role of drug-loaded nanoparticles through the electrospraying process as noninvasive materials in the biomedical field.


Assuntos
Sistemas de Liberação de Medicamentos , Nanopartículas , Sistemas de Liberação de Medicamentos/métodos , Humanos , Nanotecnologia/métodos , Preparações Farmacêuticas
14.
Cells Tissues Organs ; 211(4): 492-505, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-33596574

RESUMO

Research on synthesis, characterization, and understanding of novel properties of nanomaterials has led researchers to exploit their potential applications. When compared to other nanotechnologies described in the literature, electrospinning has received significant interest due to its ability to synthesize novel nanostructures (such as nanofibers, nanorods, nanotubes, etc.) with distinctive properties such as high surface-to-volume ratio, porosity, various morphologies such as fibers, tubes, ribbons, mesoporous and coated structures, and so on. Various materials such as polymers, ceramics, and composites have been fabricated using the electrospinning technique. Among them, polymers, especially block copolymers, are one of the useful and niche systems studied recently owing to their unique and fascinating properties in both solution and solid state due to thermodynamic incompatibility of the blocks, that results in microphase separation. Morphology and mechanical properties of electrospun block copolymers are intensely influenced by quantity and length of soft and hard segments. They are one of the best studied systems to fit numerous applications due to a broad variety of properties they display upon varying the composition ratio and molecular weight of blocks. In this review, the synthesis, fundamentals, electrospinning, and tissue engineering application of block copolymers are highlighted.


Assuntos
Nanofibras , Engenharia Tecidual , Nanofibras/química , Nanotecnologia , Polímeros/química , Porosidade , Engenharia Tecidual/métodos
15.
Turk J Chem ; 46(2): 342-355, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-38143471

RESUMO

Herein, the fabrication of electrospun nanocomposites, using polyacrylonitrile nanofibers (PNF) modified with nano-bentonite and fly ash, is explained. Further, the use of electrospun adsorbent for the remediation of Pb (II) ions from water has been explored. Pristine PNF and nanocomposites were characterized using SEM, EDX, and FTIR to analyze surface topology, elemental composition, and functional groups, respectively. The adsorptive behavior of developed adsorbents was investigated using the effects of dosage, initial concentration, time, and temperature. Pseudo-second order kinetics fit well with experimental data and the adsorption followed intra-particle diffusion. The thermodynamics study confirmed spontaneous endothermic adsorption of the heavy metal. Nanocomposites-based adsorbents showed improved adsorption capacity for Pb (II) ions compared to pristine PNF.

16.
Polymers (Basel) ; 13(13)2021 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-34202499

RESUMO

Small-diameter vascular grafts fabricated from synthetic polymers have found limited applications so far in vascular surgeries, owing to their poor mechanical properties. In this study, cylindrical nanofibrous structures of highly oriented nanofibers made from polyacrylonitrile, poly (lactide-co-glycolide) (PLGA), polycaprolactone (PCL) and poly(vinyl acetate) (PVAc) were investigated. Cylindrical collectors with alternate conductive and non-conductive segments were used to obtain highly oriented nanofibrous structures at the same time with better mechanical properties. The surface morphology (orientation), mechanical properties and suture retention of the nanofibrous structures were characterized using SEM, mechanical tester and universal testing machine, respectively. The PLGA nanofibrous cylindrical structure exhibited excellent properties (tensile strength of 9.1 ± 0.6 MPa, suture retention strength of 27N and burst pressure of 350 ± 50 mmHg) when compared to other polymers. Moreover, the PLGA grafts showed good porosity and elongation values, that could be potentially used for vascular graft applications. The combination of PLGA nanofibers with extracellular vesicles (EVs) will be explored as a potential vascular graft in future.

17.
J Colloid Interface Sci ; 585: 237-249, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33285462

RESUMO

HYPOTHESIS: Organic radical polymers with tailored pendant functionalities have emerged as exciting and promising materials for their application versatility. Moreover, eco-friendly polymer-based organic nanomaterials with redox-active pendant side groups can replace the harmful heavy metal-based inorganic materials. On the other hand, self-assembled nanomaterials are of great interest and attracted more attention recently for their promising application in different advanced fields, but it is yet challenging to predict suitable hydrophilic-lipophilic balance (HLB) for stimuli-responsive random copolymers assembly due to structural irregularity. Among several experimental techniques, electron paramagnetic resonance (EPR) spectroscopy plays a unique and promising role in revealing structural and dynamic information of nanostructured radical containing materials. EXPERIMENTS: In this study, a series of spin labeled amphiphilic random copolymers poly(methyl methacrylate-co-acrylic acid) have been synthesized and characterized by FT-IR, UV-Vis spectroscopies, TGA, DSC and water contact angle (CA) techniques. Their electrochemical properties have been determined by cyclic voltammetry (CV) in different organic solvents. EPR spectroscopy has been applied with other analytical techniques to elucidate the smart supramolecular nanoparticles (SNPs) formation, stimuli-responsiveness and structural changes through the dynamics of different molecular interactions. FINDINGS: The structural and dynamic information of self-assembled nanoparticles have been observed to be dependent on multiple-stimuli-responsiveness in different microenvironments by applying physiological and chemical parameters such as the different concentration of radicals, pH, temperature, nature of the solvent and reducing agent. The obtained results reveal the knowledge to understand insight into the mechanism for the formation of stimuli-responsive colloidal nanoparticles assembled from amphiphilic random copolymers with apt HLB value. The CV results reveal that the charge transfer process of the nanoparticles in solution was diffusion regulated and depended on the accessibility of radicals. The radical (spin labeled) polymers offer a broad way to develop stimuli-responsive materials in various colloidal nanostructures by changing the microenvironment, appreciating their potential advanced applications in electronic devices, catalysis, stimuli-triggered drug/gene delivery and reactive oxygen species (ROS) scavenger.

18.
Sci Rep ; 10(1): 19751, 2020 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-33184317

RESUMO

Textile-based Scaffolds preparation has the attractive features to fulfill the stated and implied needs of the consumer but there are still challenges of stability, elongation, appreciable bio-compatibility, and stated hydrophilic behavior. To overcome these challenges, the authors tried to fabricate a scaffold by blending of two highly biocompatible polymers; polyvinyl alcohol and poly(1,4 cyclohexane isosorbide terephthalate) through co-electrospinning. The resultant scaffold by the stated innovative approach evaluated from different characterizations such as dimensional stability/morphology was evaluated by scanning electron microscopy, chemical interactions by that Fourier transmission infrared spectra, wetting behavior was analyzed by a static angle with a contact angle meter from drop method, elongation was examined by tensile strength tester and in-vitro assessment was done by MTT analysis. Based on verified results, it was concluded that PVA/PICT scaffold has a potential for dual nature of hydrophilicity & hydrophobicity and appreciable cell culture growth, stated dimensional stability and suitable elongation as per requirements of the nature of scaffold.

19.
Phys Rev Lett ; 125(14): 143603, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33064534

RESUMO

The possibility of a superradiant phase transition in light-matter systems is the subject of much debate, due to numerous apparently conflicting no-go and counter no-go theorems. Using an arbitrary-gauge approach we show that a unique phase transition does occur in archetypal many-dipole cavity QED systems, and that it manifests unambiguously via a macroscopic gauge-invariant polarization. We find that the gauge choice controls the extent to which this polarization is included as part of the radiative quantum subsystem and thereby determines the degree to which the abnormal phase is classed as superradiant. This resolves the long-standing paradox of no-go and counter no-go theorems for superradiance, which are shown to refer to different definitions of radiation.

20.
Phys Rev Lett ; 125(4): 043603, 2020 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-32794814

RESUMO

Spectral filtering of resonance fluorescence is widely employed to improve single photon purity and indistinguishability by removing unwanted backgrounds. For filter bandwidths approaching the emitter linewidth, complex behavior is predicted due to preferential transmission of components with differing photon statistics. We probe this regime using a Purcell-enhanced quantum dot in both weak and strong excitation limits, finding excellent agreement with an extended sensor theory model. By changing only the filter width, the photon statistics can be transformed between antibunched, bunched, or Poissonian. Our results verify that strong antibunching and a subnatural linewidth cannot simultaneously be observed, providing new insight into the nature of coherent scattering.

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