Electromagnetically induced transparency and quantum enhancement of transmission via dressed bloch photons in an array of three-level Λ-type atoms.

We investigate the interactions between an array of three-level atoms and two photon fields with distinct frequencies employing quantum electrodynamics (QED). The control beam, as expected, has a considerably higher intensity than the probe beam, and the probe photon's eigenstate notably then appears as a distinctive dressed Bloch wave. We calculate the dispersion relation and quantum amplitude of the probe photons for their transmission. At positions predicting electromagnetically induced transparency (EIT) phenomena, we unveil remarkable enhancements in the transmission of the probe beam. Crucially, these enhancements are intricately linked to the unique characteristics of the dressed Bloch wave eigenstate. Moreover, we demonstrate that modulating frequency and intensity of the control beam and the lattice constant would further tune these enhancements. Our study highlights the crucial role of the dressed Bloch wave eigenstate in substantially amplifying targeted light beams, thereby significantly enhancing the detection sensitivity for minute electromagnetic signals and emphasizing its pivotal role in unveiling intriguing phenomena.

Novel salty peptides derived from bovine bone: Identification, taste characteristic, and salt-enhancing mechanism.

Excessive sodium intake is a major contributor to the incidence of cardiovascular diseases. The objective of this study was to prepare, isolate, and characterize peptides from bovine bone protein and investigate the salty/salt-enhancing mechanism of peptides. 1032 peptides were identified in the enzymatic hydrolysates of bovine bone protein and were further screened by the composition of amino acid residues and molecular docking analysis. 5 peptides were finally selected for solid-phase synthesis, and KER showed a better salty taste by sensory verification. Moreover, the synergistic effect of KER in NaCl and MSG solution could enhance the salty intensity by 65.26 %. The binding of KER to the salty receptor (TMC4) was driven by hydrogen bonding and electrostatic interactions with a binding energy of -88.0734 kcal/mol. This work may provide a new approach to efficiently screen salty peptides from natural food materials, which were expected as a taste enhancer used in salt-reducing foods.

Use of a wheat straw covering to reduce nitrogen loss during pig slurry storage and reuse of the straw covering in biochar production for nitrogen retention in the slurry.

Storing pig slurry (PS) and returning it to the field is one of the most important ways to recycle PS. However, during the storage of PS, the NH3 emissions cause a large loss of nitrogen (N), which reduces the fertilizer value of stored PS and cause environmental pollution. To reduce N loss during PS storage, we added different amounts of wheat straw powder (WSP) and wheat straw segments (WSSs) to the PS. The wheat straw cover was used for biochar production, and then, the biochar was used for N adsorption from the PS. The results showed that the N loss of PS was significantly decreased by use of the wheat straw covering. The N losses in treatments of WSP covering and WSSs covering were reduced by 4.8-53.1 and 0.8-14.2 percentage points compared with that in the control, respectively. Ammonia adsorption is an important reason for the reduction in N loss by straw covering during PS storage. After covering for 180 days in storage, the NH4+-N content in both the WSP covering and WSSs covering increased greatly, and the cover was reused for biochar production. The biochar yield was inversely proportional to the pyrolysis temperature, and the specific surface area and pore volume of the biochar were proportional to the pyrolysis temperature. We achieved the highest amount of NH4+-N adsorption (1.9 mg/g) with a biochar dosage of 0.2 g/L (treatment Y-400). This study provides a new straw-covered PS storage method to achieve straw recycling and low N loss during PS storage.

Cascade utilization of rice straw for biogas production.

To improve the biogas yield of rice straw, an innovative cascade utilization process for biogas production was proposed using a method referred to as "the first digestion + NaOH treatment + the second digestion" (labeled FSD). Both the first digestion and the second digestion of all treatments were conducted at the initial total solid (TS) loading of straw of 6%. A series of lab-scale batch experiments were conducted to investigate the effect of first digestion time (5, 10, and 15 days) on biogas production and lignocellulose structure destruction of rice straw. The results showed that the cumulative biogas yield of rice straw using the FSD process was increased by 13.63-36.14% compared with the control (CK), and the highest biogas yield of 233.57 mL g-1 TSadded was obtained when the first digestion time was 15 days (FSD-15). The removal rates of TS, volatile solids, and organic matter were increased by 12.21-18.09%, 10.62-14.38%, and 13.44-16.88%, respectively, compared with those of CK. The results of Fourier transform infrared spectroscopy analysis revealed that the skeletal structure of rice straw was not significantly destroyed after the FSD process, but the relative contents of functional groups in rice straw were changed. The FSD process accelerated the destruction of crystallinity of rice straw, and the lowest crystallinity index of 10.19% was obtained at FSD-15. The abovementioned results indicated that the FSD-15 process is recommended for cascade utilization of rice straw in biogas production.

Manipulating quantum interference of dressed photon fields.

Through quantum electrodynamics (QED) we investigate the interactions between a three-level atom and two photon fields under perturbation limit. The dispersion relation and (relative) transmission of the probe photons are obtained by calculating the corresponding Feynman diagrams. The quantum interference in this three-level system such as Fano resonance and electromagnetically induced transparency (EIT) can be tuned by varying the intensities of the control and probe beams. Moreover, by considering that the control beam with periodic modulation, that is, the so-called Landau-Zener-Stückelberg (LZS) type source, the accumulated phase after Landau-Zener transitions is found to show the alternating Fano (EIT) lineshapes in the transmission of the probe photons. We further find that the transmissions can become almost stationary in addition to a wide EIT window in time even though the control beam is a LZS-type oscillating source.

Optical quantum frequency filter based on generalized eigenstates.

Bound eigenstates and generalized eigenstates (scattering eigenstates) are two kinds of eigenstates in quantum mechanics. In this work, we first introduce a systematic way to regularize a generalized eigenstates by using the Wick rotation. The states that can be regularized are, in fact, Gamow states since they form poles in the scattering matrix but not localized before the Wick rotation. We then demonstrate an example where a bosonic field interacting with an array of two level systems can have Gamow states with positive real eigenenergies, and the scattering spectrum diverges at the eigenenergy. Since the eigenenergies of this kind locate in a real continuous scattering spectrum, from the scattering matrix point of view, these states resemble the bound states in the continuum (BIC). Unlike BIC, however, these states are non-localized in space and possess the frequency-filtering nature which may lead to potential applications in tunable quantum frequency filters for scattering states.

Photon-Assisted Perfect Conductivity Between Arrays of Two-Level Atoms.

We investigate interactions between two (parallel) arrays of two-level atoms (2LA) via photons through quantum electrodynamical interaction with one array (the source array) connected to a particle source, and we study the (photo-)resistivity of the other array (the measured array). The wave function of the interacted photon propagating in an array is a Bloch wave with a gap in its eigenvalue (the photonic dispersion). Due to interactions between arrayed 2LA and the dressed photonic field with non-linear dispersion, the conduction behaviors of the measured array can be very diversified according to the input energy of the particle source connected to the source array, and their relative positions. As a result, the resistivity of the measured array can be zero or negative, and can also be oscillatory with respect to the incoming energy of the particle source of the source array, and the separation between arrays.

Transport of Photonic Bloch Wave in Arrayed Two-Level Atoms.

In a quantum system of arrayed two-level atoms interacting with light, the interacted (dressed) photon is propagating in a periodic medium and its eigenstate ought to be of Bloch type with lattice symmetry. As the energy of photon is around the spacing between the two atomic energy levels, the photon will be absorbed and is not in the propagating mode but the attenuated mode. Therefore an energy gap exists in the dispersion relation of the photonic Bloch wave of dressed photon in addition to the nonlinear behaviors due to atom-light interactions. There follows several interesting results which are distinct from those obtained through a linear dispersion relation of free photon. For example, slow light can exist, the density of state of dressed photon is non-Lorentzian and is very large around the energy gap; the Rabi oscillations become monotonically decreasing in some cases; and besides the superradiance occurs at long wavelengths, the spontaneous emission is also very strong near the energy gap because of the high density of state.

Spatio-Temporal Steering for Testing Nonclassical Correlations in Quantum Networks.

We introduce the concept of spatio-temporal steering (STS), which reduces, in special cases, to Einstein-Podolsky-Rosen steering and the recently-introduced temporal steering. We describe two measures of this effect referred to as the STS weight and robustness. We suggest that these STS measures enable a new way to assess nonclassical correlations in an open quantum network, such as quantum transport through nano-structures or excitation transfer in a complex biological system. As one of our examples, we apply STS to check nonclassical correlations among sites in a photosynthetic pigment-protein complex in the Fenna-Matthews-Olson model.

Plasmonic bio-sensing for the Fenna-Matthews-Olson complex.

We study theoretically the bio-sensing capabilities of metal nanowire surface plasmons. As a specific example, we couple the nanowire to specific sites (bacteriochlorophyll) of the Fenna-Matthews-Olson (FMO) photosynthetic pigment protein complex. In this hybrid system, we find that when certain sites of the FMO complex are subject to either the suppression of inter-site transitions or are entirely disconnected from the complex, the resulting variations in the excitation transfer rates through the complex can be monitored through the corresponding changes in the scattering spectra of the incident nanowire surface plasmons. We also find that these changes can be further enhanced by changing the ratio of plasmon-site couplings. The change of the Fano lineshape in the scattering spectra further reveals that "site 5" in the FMO complex plays a distinct role from other sites. Our results provide a feasible way, using single photons, to detect mutation-induced, or bleaching-induced, local defects or modifications of the FMO complex, and allows access to both the local and global properties of the excitation transfer in such systems.

Scattering of nanowire surface plasmons coupled to quantum dots with azimuthal angle difference.

Coherent scatterings of surface plasmons coupled to quantun dots have attracted great attention in plasmonics. Recently, an experiment has shown that the quantum dots located nearby a nanowire can be separated not only in distance, but also an angle ϕ along the cylindrical direction. Here, by using the real-space Hamiltonian and the transfer matrix method, we analytically obtain the transmission/reflection spectra of nanowire surface plasmons coupled to quantum dots with an azimuthal angle difference. We find that the scattering spectra can show completely different features due to different positions and azimuthal angles of the quantum dots. When additionally coupling a cavity to the dots, we obtain the Fano-like line shape in the transmission and reflection spectra due to the interference between the localized and delocalized modes.

Dressed Photons Induced Resistance Oscillation and Zero Resistance in Arrayed Simple Harmonic Oscillators with No Impurity.

We investigate a system of an array of N simple harmonic oscillators (SHO) interacting with photons through QED interaction. As the energy of photon is around the spacing between SHO energy levels, energy gaps appear in the dispersion relation of the interacted (dressed) photons. This is quite different from the dispersion relation of free photons. Due to interactions between dressed photonic field and arrayed SHO, the photoresistance of this system shows oscillations and also drops to zero as irradiated by EM field of varying frequencies.

Probing the spectral density of the surface electromagnetic fields through scattering of waveguide photons.

The spectral density of the metal-surface electromagnetic fields will be strongly modified in the presence of a closely-spaced quantum emitter. In this work, we propose a feasible way to probe the changes of the spectral density through the scattering of the waveguide photon incident on the quantum emitter. The variances of the lineshape in the transmission spectra indicate the coherent interaction between the emitter and the pseudomode resulting from all the surface electromagnetic modes. We further investigate the quantum coherence between the emitter and the pseudomode of the metal-dielectric interface.

Methane production from wheat straw with anaerobic sludge by heme supplementation.

Wheat straw particles were directly used as substrate for batch anaerobic digestion with anaerobic sludge under 35°C to evaluate the effects of adding heme on methane production. When 1mg/l heme was added to the fermentation process with no agitated speed, a maximum cumulative methane production of 12227.8ml was obtained with cumulative methane yield of wheat straw was 257.4ml/g-TS (total solid), which was increased by 20.6% compared with 213.5ml/g-TS of no heme was added in the reactor. Meanwhile, oxido-reduction potential (ORP) level was decreased, the activity of coenzyme F420 was significantly improved and NADH/NAD(+) ratio were the highest than other experimental groups. These results suggest that heme-supplemented anaerobic sludge with no agitated speed may be providing a more reductive environment, which is a cost-effective method of anaerobic digestion from biomass waste to produce methane with less energy consuming.

[Effect of pretreatment on storage and biogas production of baling wheat straw].

Long-term storage of crop straw is very important for biogas plant while pretreatment is always used to improve biogas production of crop straw. Feasibility of integrating the storage with pretreatment of baling wheat straw was studied. Changes of physicochemical properties and the biogas productivity of wheat straw obtained before and after 120 days storage were analyzed. The results showed that it was feasible to directly bale wheat straw for storage (control) and storage treatment had little effect on the physicochemical properties, structure and biogas productivity of wheat straw. After 120 day's storage, biogas production potential of the surface wheat straw of pile was decreased by 7.40%. Integrating NaOH pretreatment with straw storage was good for biogas production of wheat straw and the total solid (TS) biogas yield was increased by 7.02%-8.31% (compared to that of wheat straw without storage) and 5.68% -16.96% (compared to that of storage without alkaline pretreatment), respectively. Storage with urea treatment was adverse to biogas production of wheat straw and the contents of cellulose and hemicellulose of wheat straw were decreased by 18.25%-27.22% and 5.31%-16.15% and the TS biogas yield was decreased by 2.80%-7.71% after 120 day's storage. Exposing wheat straw to the air during the storage process was adverse to the conserving of organic matter and biogas utilization of wheat straw, but the influence was very slight and the TS biogas yield of wheat straw obtained from pile surface of control and urea treatment was decreased by 7.40% and 4.25%, respectively.

Rerouting excitation transfers in the Fenna-Matthews-Olson complex.

We investigate, using the hierarchy method, the entanglement and the excitation transfer efficiency of the Fenna-Matthews-Olson (FMO) complex under two different local modifications: the suppression of transitions between particular sites and localized changes to the protein environment. We find that inhibiting the connection between site 5 and site 6, or completely disconnecting site 5 from the complex, leads to a dramatic enhancement of the entanglement between site 6 and site 7. Similarly, the transfer efficiency actually increases if site 5 is entirely disconnected from the complex. We further show that if sites 5 and 7 are conjointly removed, the efficiency falls. This suggests that while not contributing to the transport efficiency in a normal complex, site 5 may introduce a redundant transport route in case of damage to site 7. Our results suggest an overall robustness of the excitation-energy transfer in the FMO complex under mutations, local defects, and other abnormal situations.

Examining non-locality and quantum coherent dynamics induced by a common reservoir.

If two identical emitters are coupled to a common reservoir, entanglement can be generated during the decay process. When using Bell's inequality to examine the non-locality, however, it is possible that the bound cannot be violated in some cases. Here, we propose to use the steering inequality to examine the non-locality induced by a common reservoir. Compared with the Bell inequality, we find that the steering inequality has a better tolerance for examining non-locality. In view of the dynamic nature of the entangling process, we also propose to observe the quantum coherent dynamics by using the Leggett-Garg inequalities. We also suggest a feasible scheme, which consists of two quantum dots coupled to nanowire surface plasmons, for possible experimental realization.

Witnessing Quantum Coherence: from solid-state to biological systems.

Quantum coherence is one of the primary non-classical features of quantum systems. While protocols such as the Leggett-Garg inequality (LGI) and quantum tomography can be used to test for the existence of quantum coherence and dynamics in a given system, unambiguously detecting inherent "quantumness" still faces serious obstacles in terms of experimental feasibility and efficiency, particularly in complex systems. Here we introduce two "quantum witnesses" to efficiently verify quantum coherence and dynamics in the time domain, without the expense and burden of non-invasive measurements or full tomographic processes. Using several physical examples, including quantum transport in solid-state nanostructures and in biological organisms, we show that these quantum witnesses are robust and have a much finer resolution in their detection window than the LGI has. These robust quantum indicators may assist in reducing the experimental overhead in unambiguously verifying quantum coherence in complex systems.

Delocalized single-photon Dicke states and the Leggett-Garg inequality in solid state systems.

We show how to realize a single-photon Dicke state in a large one-dimensional array of two-level systems, and discuss how to test its quantum properties. The realization of single-photon Dicke states relies on the cooperative nature of the interaction between a field reservoir and an array of two-level-emitters. The resulting dynamics of the delocalized state can display Rabi-like oscillations when the number of two-level emitters exceeds several hundred. In this case, the large array of emitters is essentially behaving like a "mirror-less cavity". We outline how this might be realized using a multiple-quantum-well structure or a dc-SQUID array coupled to a transmission line, and discuss how the quantum nature of these oscillations could be tested with an extension of the Leggett-Garg inequality.

Correspondence between entanglement and Fano resonance of surface plasmons.

We investigate the Fano resonance of the scattering spectra in a system consisting of a metal nanowire coupled to two colloidal quantum dots. By varying the coupling strengths and the energy spacings of the quantum dot qubits, we find that both the line shapes and the presence of the Fano resonance can be controlled. Furthermore, the degree of two-qubit entanglement can vary from unity to zero when the Fano resonance occurs. This indicates that there exists correlations between the two-qubit entanglement and the Fano resonance.