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1.
Opt Express ; 28(12): 17868-17880, 2020 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-32679989

RESUMO

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.

2.
Sci Rep ; 9(1): 13033, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31506596

RESUMO

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.

3.
Sci Rep ; 8(1): 1519, 2018 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-29367748

RESUMO

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.

4.
Sci Rep ; 7(1): 3728, 2017 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-28623284

RESUMO

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.

5.
Sci Rep ; 7: 39720, 2017 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-28045089

RESUMO

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.


Assuntos
Proteínas de Bactérias/química , Técnicas Biossensoriais/métodos , Complexos de Proteínas Captadores de Luz/química , Ressonância de Plasmônio de Superfície/métodos , Proteínas de Bactérias/genética , Transferência de Energia , Complexos de Proteínas Captadores de Luz/genética , Metais/química , Modelos Teóricos , Nanoestruturas/química
6.
Sci Rep ; 6: 37766, 2016 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-27892942

RESUMO

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.

7.
Sci Rep ; 6: 37763, 2016 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-27886252

RESUMO

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.

8.
Sci Rep ; 6: 21673, 2016 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-26860197

RESUMO

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.

9.
Huan Jing Ke Xue ; 34(8): 3280-5, 2013 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-24191580

RESUMO

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.


Assuntos
Biocombustíveis , Triticum , Celulose/química , Fenômenos Químicos , Caules de Planta , Hidróxido de Sódio/química , Ureia/química
10.
Artigo em Inglês | MEDLINE | ID: mdl-24125226

RESUMO

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.

11.
Sci Rep ; 3: 2514, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23979099

RESUMO

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.


Assuntos
Retroalimentação , Modelos Teóricos , Pontos Quânticos , Teoria Quântica , Ressonância de Plasmônio de Superfície/métodos , Simulação por Computador
12.
Sci Rep ; 2: 869, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23162693

RESUMO

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.

13.
Sci Rep ; 2: 885, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23185690

RESUMO

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.


Assuntos
Complexos de Proteínas Captadores de Luz , Teoria Quântica , Nanoestruturas
14.
Opt Lett ; 37(19): 4023-5, 2012 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23027266

RESUMO

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.

15.
Opt Lett ; 37(8): 1337-9, 2012 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-22513678

RESUMO

Generating entangled states is a vital ingredient for quantum information engineering. Here, we investigate the entanglement generation between two quantum dots coupled to nanoring surface plasmons with asymmetric coupling strength g(1) and g(2). The dynamics of concurrence C is obtained by solving the corresponding master equation. High entanglement can be generated at appropriate times through the scatterings of the incident field and its scattered field. Furthermore, we find that maximum entanglement can be created when r≡g(1)/g(2) is the ratio of odd numbers. Contrary to intuition, relative high entanglement (C≃1) can remain even if the ratio r is far off the required values, which is useful in real experiments.

16.
Huan Jing Ke Xue ; 33(1): 203-7, 2012 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-22452211

RESUMO

The characteristics of Spartina alterniflora residue after producing methane (SAR) digested alone and co-digestion of various proportions of chicken manure and SAR were investigated by batch model at 35 degrees C +/- 1 degrees C. The initial total solid (TS) loading of all treatments was 8.0%. The results indicated that there was still some biogas produced by SAR with TS biogas yield of 107.25 mL x g(-1) and average methane content of 76.92%. The cellulose crystallinity of re-digested SAR was destructed by anaerobic microorganisms, and the destruction rate was 5.55%. Co-digestion meliorated the environment where microorganisms lived in and increased the cumulative biogas yield. When the ratio of chicken manure to SAR was 4 : 1, the cumulative biogas yield was highest while the cumulative biogas yield of T1 (the rate of chicken manure to SAR is 5 : 0 based on TS), T3-T6 (the rate of chicken manure to SAR are 3 : 2, 2 : 3, 1 :4 and 0 : 5 based on TS, respectively) were 61.31%, 62.09%, 52.15%, 39.74% and 31.67% of it. The anaerobic fermentation type of co-digestion is mix acid type fermentation. Co-digested with chicken manure promoted the destruction of cellulous crystallinity by 1.13% - 21.61% and especially when the rate of chicken manure to SAR was 4 : 1.


Assuntos
Fermentação , Esterco , Metano/metabolismo , Poaceae/metabolismo , Anaerobiose , Animais , Galinhas , Poaceae/microbiologia
17.
Huan Jing Ke Xue ; 33(12): 4406-11, 2012 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-23379172

RESUMO

Alkaline treatment is widely used for improving biogas production for lignocellulosic materials. This study was conducted to investigate the effect of alkaline treatment on physicochemical property of digested Spartina alterniflora (DSA). Fourier Transform Infrared Spectroscopy (FTIR), X-Ray diffraction patterns, proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), solid-state 13C-NMR Spectroscopy and some general indicators were used to analyze changes of the lignocellulosic structure and composition of NaOH-treated digested Spartina alterniflora. The results showed that, after NaOH treatment, surface lignin and some carbohydrate were destructed into lignin fragment, organic acids and some other small molecular organic matter, but the skeleton structure of lignin and cellulose of DSA were not destructed significantly. The crystalline of cellulose of DSA was transferred into biodegradable forms and content of crystalline of DSA and cellulose were increased after NaOH treatment. The results of 13C-NMR showed that methyl (CH3) and carboxylic C(COOH) groups of DSA were decomposed significantly.


Assuntos
Fenômenos Químicos/efeitos dos fármacos , Fermentação , Poaceae/metabolismo , Hidróxido de Sódio/química , Anaerobiose , Biodegradação Ambiental , Biocombustíveis/análise , Celulose/metabolismo , Poaceae/química
18.
Huan Jing Ke Xue ; 32(7): 2158-63, 2011 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-21922846

RESUMO

In order to improve the biotransformation rate of lignocellulosic materials, sodium hydroxide (NaOH) was widely used to pretreat lignocellulosic materials. Effect of NaOH-treatment on dry-thermophilic anaerobic digestion of Spartina alternflora was studied by batch model under the temperature of 55 degrees C +/- 1 degrees C, at the initial total solid loading (TSL) of 20%. The results indicated that biogas production was inhibited by NaOH-treatment and improved by NaOH-treatment with water washed. The cumulative biogas yield of control (CK), NaOH-treated and NaOH-treated with water washed (NaOH + water) were 268.35 mL/g, 205.76 mL/g and 299.97 mL/g, respectively. The methane content of CK and NaOH + water treatments kept stable while fluctuation of NaOH-treated treatment during anaerobic digestion process was observed. Compared with CK and NaOH + water treatments, methane content of NaOH-treated treatment was improved by 5.30%. The content of hemi-cellulose and cellulose of S. alternifora decreased while content of lignin of S. alterniflora increased after 51-day anaerobic digestion. The crystallinity of cellulose of S. alterniflora increased after NaOH-treatment which was consistent to the result of FTIR. The lignocellulosic structure was destroyed and the biodegradability of S. alterniflora was increased by NaOH pretreatment. However, the amount of Na+ was taken into the anaerobic system, besides the high Na+ content in the plant itself which inhibited the anaerobic microorganisms. Therefore, NaOH-treatment is considered to be unsuitable for the anaerobic digestion of S. alterniflora.


Assuntos
Biocombustíveis/análise , Celulose/metabolismo , Fermentação , Poaceae/metabolismo , Hidróxido de Sódio/química , Anaerobiose , Biodegradação Ambiental , Poaceae/efeitos dos fármacos
19.
Opt Lett ; 36(18): 3602-4, 2011 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-21931404

RESUMO

We theoretically study the effect of the applied magnetic field on the scattering properties of the nanowire surface plasmons coupled to two quantum dots. The dispersion relations of the surface plasmon are found to be upwardly displaced in the presence of an applied magnetic field. The symmetric double peaks in the transmission spectrum resulting from the interference between the localized and delocalized channels of the surface plasmon can combine together and the associated Fano lineshape will be smeared out when increasing the magnitude of the magnetic field.

20.
Huan Jing Ke Xue ; 32(11): 3425-8, 2011 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-22295645

RESUMO

Biogas residue of Spartina alterniflora treated by NaOH solution for 48h at room temperature was used for secondary anaerobic digestion with TS loading rates were 8%, 10%, 12% at (35 +/- 1) degrees C. The biogas yield, pH, and volatile fatty acid (VFA) were analyzed during the anaerobic digestion. The peak of daily gas production were 10, 14, 13 mL x g(-1) and the rates of cumulate gas production were 217, 227, 228 mL x g(-1) respectively. The methane content exceeded 65% and the lowest pH value was 7.04 during the process. The concentrations of acetic acid concentrations were 3 364, 3 286, 5 728 mg x L(-1) respectively while propionic acid and butyric acid concentrations were below 1 100 mg x L(-1). Biogas residue as a non-degradation organic compound with high potential biogas yield was decomposed slowly and no acid accumulation was not observed.


Assuntos
Bactérias Anaeróbias/metabolismo , Biocombustíveis/análise , Fermentação , Poaceae/metabolismo , Anaerobiose , Biodegradação Ambiental , Hidróxido de Sódio/química
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