Charged Condensate Research Articles

Dynamic superconductivity responses in photoexcited optical conductivity and Nernst effect

High-${T}_{\mathrm{c}}$ cuprate, alkali-doped ${\mathrm{C}}_{60}$, and several other unconventional superconductors have very high transition temperatures ${T}_{\mathrm{c}}$ with respect to the energy scale of superconducting (SC) charges inferred from the superfluid density (SFD). The observed linear relationship between ${T}_{\mathrm{c}}$ and the SFD can hardly be expected in BCS superconductors while being reminiscent of Bose-Einstein condensation of preformed bosonic charges. As additional non-BCS-like behaviors, responses similar to those in the bulk SC states have been observed at temperatures well above ${T}_{\mathrm{c}}$ in the vortexlike Nernst effect, diamagnetic susceptibility, and transient optical conductivity in recent photoexcited pump-probe measurements. In this paper, we propose a coherent picture based on equilibrium and transient SFD to understand these unconventional behaviors in cuprates, ${\mathrm{K}}_{3}{\mathrm{C}}_{60}$, and organic superconductors. This picture assumes: (1) Dynamic SC responses in the Nernst and photoinduced measurements emerge at the formation of the local phase coherence (LPC) among wave functions of preformed bosonic pairs. (2) Its onset temperature ${T}_{\mathrm{LPC}}$ is distinct from and lower than the boson formation temperature often denoted as the ``pseudogap temperature'' ${T}^{*}$, as ${T}_{\mathrm{LPC}}$ is determined by the many-body boson density while ${T}^{*}$ represents attractive interaction between two fermions. (3) The bulk superconducting ${T}_{\mathrm{c}}$, signaling global phase coherence, is significantly reduced from ${T}_{\mathrm{LPC}}$, due to the competition between the SC and antiferromagnetic (AF) order. (4) The inelastic magnetic resonance mode (MRM) controls ${T}_{\mathrm{c}}$ in the SC-AF competition. (5) The transient optical responses can be attributed to a change of the balance between the competing SC and AF orders caused by photoexcitation. The assumptions (1) and (2) explain the relationship between ${T}_{\mathrm{c}}$ and the transient SFD in photoexcited studies and equilibrium SFD in Nernst effect. (3) and (4) are inferred from the linear dependence of ${T}_{\mathrm{c}}$ on the MRM energy. (4) and (5) are consistent with the behaviors of the $400\ensuremath{-}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$ optical responses in equilibrium and photoexcited studies and temperature dependence of the intensity of this optical mode and the MRM. Unlike previous phase-fluctuation pictures which expect dynamic responses between ${T}^{*}$ and ${T}_{\mathrm{c}}$, the present picture involving competing order indicates that dynamic SC responses are seen between ${T}_{\mathrm{LPC}}$ and ${T}_{\mathrm{c}}$.

Pion Condensation in Hot Dense Quark Matter with Isospin and Chiral-Isospin Asymmetries within the Nambu—Jona-Lasinio Model

The phase portrait of dense quark matter is investigated within the (3 + 1)-dimensional Nambu—Jona-Lasinio model taking the isospin and chiral-isospin asymmetries in quarks into account. It is shown that the chiral-isospin chemical potential contributes to the generation of the phase with charged pion condensation.

Charged pion condensation and duality in dense and hot chirally and isospin asymmetric quark matter in the framework of the NJL2 model

In this paper we investigate in the large-$N_c$ limit ($N_c$ is the number of colored quarks) the phase structure of a massless (1+1)-dimensional quark model with four-quark interaction and in the presence of baryon ($\mu_B$), isospin ($\mu_I$) and chiral isospin ($\mu_{I5}$) chemical potentials as well as at nonzero temperature. It is established that chiral isospin chemical potential leads to the generation of charged pion condensation (PC) in dense (nonzero baryon density) and chiral asymmetric quark matter for a wide range of isospin densities. It is shown that there exists a duality correspondence between the chiral symmetry breaking and the charged PC phenomena at any values of temperature even for very hot quark gluon plasma. Moreover, it is shown that charged PC phase with nonzero baryon density can be induced in the model at comparatively high temperatures. This opens up new possible physical systems, where it can be of importance, such as heavy ion collisions, just born neutron stars (proto-neutron stars), supernovas as well as neutron star mergers.

Surface Characterization of Colloidal Silica Nanoparticles by Second Harmonic Scattering: Quantifying the Surface Potential and Interfacial Water Order.

The microscopic description of the interface of colloidal particles in solution is essential to understand and predict the stability of these systems, as well as their chemical and electrochemical reactivity. However, this description often relies on the use of simplified electrostatic mean field models for the structure of the interface, which give only theoretical estimates of surface potential values and do not provide properties related to the local microscopic structure, such as the orientation of interfacial water molecules. Here we apply polarimetric angle-resolved second harmonic scattering (AR-SHS) to 300 nm diameter SiO2 colloidal suspensions to experimentally determine both surface potential and interfacial water orientation as a function of pH and NaCl concentration. The surface potential values and interfacial water orientation change significantly over the studied pH and salt concentration range, whereas zeta-potential (ζ) values remain constant. By comparing the surface and ζ-potentials, we find a layer of hydrated condensed ions present in the high pH case, and for NaCl concentrations ≥1 mM. For milder pH ranges (pH < 11), as well as for salt concentrations <1 mM, no charge condensation layer is observed. These findings are used to compute the surface charge densities using the Gouy–Chapman and Gouy–Chapman–Stern models. Furthermore, by using the AR-SHS data, we are able to determine the preferred water orientation in the layer directly in contact with the silica interface. Molecular dynamics simulations confirm the experimental trends and allow deciphering of the contributions of water layers to the total response.

Charged Pion Condensation in Dense Quark Matter: Nambu–Jona-Lasinio Model Study

In this short review we tried to give an outline of investigations of charged pion condensation (PC) in dense baryonic (quark) matter in the framework of effective Nambu–Jona-Lasinio (NJL)-type models. The possibility of charged PC phase in dense quark matter with isospin asymmetry is investigated. First, it is demonstrated that this phase can be realized in the framework of massless NJL model. However, the existence of this phase is enormously fragile to the values of current quark mass and we show that charged PC phase is forbidden in electrically neutral dense quark matter with β -equilibrium when current quark masses are close to their physical value of 5.5 MeV. Nevertheless, then it is shown that in real physical systems there could be conditions promoting the appearance of charged PC phenomenon in dense quark matter; specifically, it was shown that if one takes into consideration the fact that system can have finite size, then a dense charged PC phase can be realized there. It was also demonstrated that the possibility of inhomogeneous pion condensate might allow this phase to appear. In addition, more recently it was revealed that there is another interesting factor that can induce a charged PC phase in dense quark matter even without isospin imbalance. It is a chiral imbalance of the system (non-zero difference between densities of left- and right-handed quarks). These results can be interesting in heavy ion collision experiments, where it is expected to get high baryon densities. It is of interest also in the context of neutron stars, where quark matter might be realized in the core and very high baryon and isospin densities are attained.

Dualities and inhomogeneous phases in dense quark matter with chiral and isospin imbalances in the framework of effective model

It has been shown in [15, 70] in the framework of Nambu-Jona-Lasinio model with the assumption of spatially homogeneous condensates that in the large-Nc limit (Nc is the number of quark colours) there exist three dual symmetries of the thermodynamic potential, which describes dense quark matter with chiral and isospin imbalances. The main duality is between the chiral symmetry breaking and the charged pion condensation phenomena. There have been a lot of studies and hints that the ground state could be characterized by spatially inhomogeneous condensates, so the question arises if duality is a rather deep property of the phase structure or just accidental property in the homogeneous case. In this paper we have shown that even if the phase diagram contains phases with spatially inhomogeneous condensates, it still possesses the property of this main duality. Two other dual symmetries are not realized in the theory if it is investigated within an inhomogeneous approach to a ground state. Based on various previously studied aspects of the QCD phase diagram of dense isospin asymmetric matter with possible inhomogeneous condensates, in the present paper a unified picture and full phase diagram of dense quark matter with isospin imbalance have been assembled. Acting on this diagram by a dual transformation, we obtained, in the framework of an approach with spatially inhomogeneous condensates and without any calculations, a full phase diagram of chirally asymmetric dense medium. This example shows that the duality is not just entertaining mathematical property but an instrument with very high predictivity power. The obtained phase diagram is quite rich and contains various spatially inhomogeneous phases.

Chiral imbalanced hot and dense quark matter: NJL analysis at the physical point and comparison with lattice QCD

Hot and dense quark matter with isospin and chiral imbalances is investigated in the framework of the (3+1)-dimensional Nambu–Jona-Lasinio model (NJL) in the large-N_c limit (N_c is the number of quark colors). Its phase structure is considered in terms of barion – mu _B, isospin – mu _I and chiral isospin – mu _{I5} chemical potentials. It is shown in the paper that (i) in the chiral limit there is a duality between chiral symmetry breaking (CSB) and charged pion condensation (PC) phenomena. (ii) At the physical point, i.e. at nonzero bare quark mass m_0, and temperature this duality relation is only approximate, although rather accurate. (iii) We have shown that the chiral isospin chemical potential mu _{I5} in dense quark matter generates charged pion condensation both at zero and nonzero m_0, and at mu _{I5}ne 0 this phase might be observed up to temperatures as high as 100 MeV. (iv) Pseudo-critical temperature of the chiral crossover transition rises in the NJL model with increasing mu _{I5}. (v) It has been found an agreement between particular sections of the phase diagram in the framework of NJL model and corresponding ones in lattice QCD simulations. Two different plots from different lattice simulations that are completely independent and are not connected at the first sight are in reality dual to each other, it means that lattice QCD simulations support the hypothesis that in real quark matter there exists the (approximate) duality between CSB and charged PC. Moreover, we can reverse the logic and we can predict the increase of pseudo-critical temperature with chiral chemical potential, the much debated effect recently, just by the duality notion, hence bolster confidence in this result (lattice QCD showed this feature for unphysically large pion mass) and put it on the considerably more solid ground.

Charged Polariton Luminescence from an Organic Semiconductor Microcavity

Strong coupling light to polaron optical transitions in an organic semiconductor microcavity leads to an unusual class of polariton that possesses a net charge. This species may offer a range of technologically useful optoelectronic properties but has thus far only been observed in passive reflectivity measurements. Here, we report room-temperature photoluminescence from both upper and lower branch polaron polariton states that originate from hole excitations in a p-doped 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC) microcavity. Our observations under nonresonant excitation are in good agreement with classical dipole emission modeling, which suggests that polariton states in this system are populated radiatively via fluorescence from the polaron excited state reservoir. These results constitute one of the first observations of polaron luminescence from an organic semiconductor thin film and are an important prerequisite for realizing a charged polariton condensate.

Symmetry-Enriched Fracton Phases from Supersolid Duality.

Motivated by the recently established duality between elasticity of crystals and a fracton tensor gauge theory, we combine it with boson-vortex duality, to explicitly account for bosonic statistics of the underlying atoms. We thereby derive a hybrid vector-tensor gauge dual of a supersolid, which features both crystalline and superfluid order. The gauge dual describes a fracton state of matter with full dipole mobility endowed by the superfluid order, as governed by "mutual" axion electrodynamics between the fracton and vortex sectors of the theory, with an associated generalized Witten effect. Vortex condensation restores U(1) symmetry, confines dipoles to be subdimensional (recovering the dislocation glide constraint of a commensurate quantum crystal), and drives a phase transition between two distinct fracton phases. Meanwhile, condensation of elementary fracton dipoles and charges, respectively, provide a gauge dual description of the superhexatic and ordinary superfluid. Consistent with conventional wisdom, in the absence of crystalline order, U(1)-symmetric phases are prohibited at zero temperature via a mechanism akin to deconfined quantum criticality.

Advances in Polymeric Materials for Electromechanical Devices.

Electroactive polymers (EAP) provide lightweight and cost-effective materials that enable the next generation of electromechanical devices. Commercial polymers have historically dominated research in EAP devices due to their availability. However, several drawbacks of these materials have limited their commercial applications, necessitating new materials for the commercial success of future EAP devices. This review highlights recent advances in novel EAPs for ionic polymer-metal composites (IPMC) and dielectric elastomer actuators (DEA). Ion-containing block copolymers and charged segmented condensation polymers demonstrate suitable electromechanical properties competitive with Nafion-based IPMCs. In addition, swelling ionic polymer membranes with free ionic liquid enhances ionic conductivity and promotes electromechanical actuation. Synthetic approaches to increasing permittivity in dielectric elastomers are also explored as a method of producing more efficient DEAs. Incorporating polar functional groups into siloxane and acrylic elastomers through grafting or blending provides high-dielectric elastomers for use in DEAs with low driving voltages.

Using Ion–Molecule Reactions To Overcome Spectral Interferences in ICP-MS: A Guided Inquiry Approach for Upper-Level Undergraduate and Graduate Students

Almost all commercial quadrupole ICP-MS instruments use collision/reaction cells to either attenuate spectral interferences or shift the analyte of interest to an interference-free m/z (e.g., by O addition). A laboratory practical was developed to introduce the students to the basic operating principles of ICP-MS using a hands-on approach, with an emphasis on practical strategies for the effective use of reaction cells in ICP-MS. Vanadium, and the ClO+ diatomic interference formed in HCl matrixes, was used as an illustrative example, which enabled students to explore charge transfer, clustering, condensation, and oxygen atom addition reactions of a single analyte, and evaluate the most effective approach for the chemical resolution of V+ and ClO+ ions. This laboratory practical provided graduate students with a basic skill set to support the effective use of ICP-MS with reaction cell technology in their research projects.

A networked swellable dextrin nanogels loading Bcl2 siRNA for melanoma tumor therapy

In this study, a networked swellable dextrin nanogel (DNG) was developed to achieve stimulated responsive small interfering RNA (siRNA) release for melanoma tumor therapy. siRNA was loaded into multidimensional dextrin nanogels by charge condensation with positive arginine residues modified in the dextrin backbone. Moreover, the networked nanogel was destroyed and loosened based on its bioreducible responsive property to control accelerated siRNA release in a bioreducible intracellular environment, while it remained stable under normal physiological conditions. We demonstrated that DNGs had swellable and disassembly properties under reduced buffer condition by transmission electron microscopy evaluation. The DNGs achieved an endosomal escape followed by selective release of the cargo into the cytosol by glutathione-triggered disassembly according to confocal microscopy observation. Thus, this smart nanogel achieved outstanding luciferase gene silencing efficiency and decreased Bcl2 protein expression in vitro and in vivo based on western blot analysis. Moreover, this nanogel exhibited superior anti-tumor activity for B16F10 xenograft tumors in C57BL/6 mice. These results demonstrate that the networked DNGs are effective for gene condensation and controlled intracellular release for tumor therapy. Overall, these findings suggest that this multidimensional swellable stimuli-responsive dextrin nanogel is an innovative strategy with great promise for gene and drug delivery.

Dense baryon matter with isospin and chiral imbalance in the framework of a NJL4 model at large Nc : Duality between chiral symmetry breaking and charged pion condensation

In this paper the phase structure of dense quark matter has been investigated in the presence of baryon, isospin and chiral isospin chemical potentials in the framework of (3+1)-dimensional Nambu--Jona-Lasinio model with two quark flavors. It has been shown that in the large-$N_{c}$ limit ($N_{c}$ is the number of colors of quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one. The key conclusion of our studies is the fact that chiral isospin chemical potential generates charged pion condensation in dense quark matter with isotopic asymmetry.

Pion Condensation by Rotation in a Magnetic Field.

We show that the combined effects of a rotation plus a magnetic field can cause charged pion condensation. We suggest that this phenomenon may yield to observable effects in current heavy ion collisions at collider energies, where large magnetism and rotations are expected in off-central collisions.

Duality and Charged Pion Condensation in Chirally Asymmetric Dense Quark Matter in the Framework of an NJL2 Model

In this talk we present investigation of the phase structure of a (1+1)-dimensional quark model with four-quark interaction and in the presence of baryon ([Formula: see text]), isospin ([Formula: see text]) and chiral isospin ([Formula: see text]) chemical potentials. Spatially homogeneous and inhomogeneous (chiral density wave (for chiral condensate) and single wave (for charged pion condensate)) condensates are considered. It is established that in the large-[Formula: see text] limit ([Formula: see text] is the number of colored quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation (PC) one. The primary conclusion of this investigation is the fact that chiral isospin chemical potential generates charged pion condensation with non-zero baryon density in dense quark matter. Moreover, it is shown that inhomogeneous charged PC phase with nonzero baryon density is induced in the model by arbitrary small values of the chemical potential [Formula: see text] (for a rather large region of [Formula: see text] and [Formula: see text]).

Unconventional phase separation in the model 2D spin-pseudospin system

The competition of charge and spin orderings is a challenging problem for strongly correlated systems, in particular, for high-Tc cuprates. We addressed a simplified static 2D spin-pseudospin model which takes into account both conventional spin exchange coupling and the on-site and inter-site charge correlations. Classical Monte-Carlo calculations for large square lattices show that homogeneous ground state antiferromagnetic solutions found in a mean-field approximation are unstable with respect to phase separation into the charge and spin subsystems behaving like immiscible quantum liquids. In this case, with lowering of a temperature one can observe two sequential phase transitions: first, antiferromagnetic ordering in the spin subsystem diluted by randomly distributed charges, then, the charge condensation in the charge droplets. The inhomogeneous droplet phase reduces the energy of the system and changes the diagram of the ground states. On the other hand, the ground state energy of charge-ordered state in a mean-field approximation exactly matches the numerical Monte-Carlo calculations. The doped charges in this case are distributed randomly over a system in the whole temperature range. Various thermodynamic properties of the 2D spin-pseudospin system are studied by Monte-Carlo simulation.

Affinity of NJL2 and NJL4 model results on duality and pion condensation in chiral asymmetric dense quark matter

In this paper we investigate the phase structure of a (1+1) and (3+1)-dimensional quark model with four-quark interaction and in the presence of baryon (μB), isospin (μI) and chiral isospin (μI5) chemical potentials. It is shown that the chemical potential μI5 promotes the appearance of the charged PC phase with nonzero baryon density. Results of both models are qualitatively the same, this fact enhances one's confidence in the obtained predictions. It is established that in the large-Nc limit (Nc is the number of colored quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one.

Investigation of Ionic Transport Through Track-Etched Conical Nanopores of PET Membrane

The control of ionic transportation inside the multi asymmetric conical nanopores in polyethylene terephthalate (PET) membrane was investigated. The conical nanopores were prepared by chemical etching in irradiated PET foil using etchant (9 M NaOH) and stopping solution (1 M NaCl [Formula: see text] 1 M HCOOH). The behavior of ionic current was recorded under stepping voltage [Formula: see text]2[Formula: see text]V to [Formula: see text]2[Formula: see text]V at different molar concentrations of potassium halides (KCl, KBr and KI) under symmetric bathing condition in electrochemical cell. It is found that the presence of multiple ionic species and the occurrence of counterion condensation of charge regulated polyelectrolyte play an effective role in ionic current rectification (ICR). The electrical conductance of conical nanopores may be estimated by measuring the ionic current rectification properties of track-etched nanopores. The charge transport properties vary with molar concentration and pH of electrolyte. Moreover, ICR may be used as a voltage gating phenomena with wide technological applications.

Charged ρ-meson condensation in neutron stars

We extend relativistic mean-field models with hadron masses and meson–baryon coupling constants dependent on the scalar field σ, including hyperons and Δ(1232) baryons, to incorporate a possibility of the charged ρ meson condensation in neutron star matter. The influence of the ρ− condensation on the equation of state proves to be strongly model dependent. In our models of one type (KVORcut-based ones) the ρ− condensation arises by a second-order phase transition above a critical density and the maximum value of the neutron star mass diminishes only slightly. The matter composition changes more significantly. In our models of other type (MKVOR*-based ones), if the system is considered at fixed density, the ρ− condensation arises by a second-order phase transition at the baryon density n=nc,ρ(II) and at a slightly higher density n=nc,ρ(I) there occurs a first-order phase transition. In a neutron star matter starting with a density n<nc,ρ(II) there appears a region of a mixed phase, or the system is described by Maxwell construction, that results in a substantial decrease of the value of the maximum neutron star mass. Nevertheless in the models under consideration the observational constraint on the maximum neutron star mass is fulfilled. Besides, in MKVOR*-based models the appearance of the ρ− condensate is accompanied by a strong rearrangement of the matter composition. Dependence of the results on a choice of the ρ meson scaling functions for the effective ρ meson mass and coupling constants is also investigated.

Hyperons, Δ resonances and condensate of charged ρ mesons within relativistic mean-field models with scaled hadron masses and couplings

We study equation of state of cold and dense baryon matter within the relativistic mean-field framework with hadron masses and coupling constants dependent on the mean scalar field. Previously constructed models with included hyperons and Δ isobars are extended taking into account possibility of the condensation of charged ρ mesons. We demonstrate that the results obtained in the models with the charged ρ-meson condensation taken into account exhibit a strong model dependence. In some of our (so-called KVORcut-based) models the charged ρ condensation does not significantly affect the value of the neutron star maximum mass. In other (so called MKVOR-based) models the neutron star maximum mass decreases substantially. All thus constructed models pass the observational constraint on the minimal value of the maximum neutron star mass.