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Tin sulfide semiconductor nanowires (NWs) have been widely investigated for photodetection applications because of their good optical and electrical properties. Herein, we synthesized n-type SnS2 NWs and then fabricated SnS2 NW photodetectors with a ferroelectric polymer side-gate. The strong electric field induced by ferroelectric polymer can effectively suppress the dark current and improve the detectivity in SnS2 NW photodetectors. The photodetectors after polarization depletion exhibit a high photoconductive gain of 4.0 × 105 and a high responsivity of 2.1 × 105 A W−1. Compared with devices without polarization depletion, the detectivity of polarization-depleted photodetectors is improved by at least two orders of magnitude, and the highest detectivity is 1.3 × 1016 Jones. Further, the rise and fall time are 56 and 91 ms respectively, which are about tens of times faster than those without polarization depletion. The device also shows a good spectral response from ultraviolet to near-infrared. This study demonstrates that ferroelectric materials can enhance optoelectronic properties of low-dimensional semiconductors for high-performance photodetectors.

We propose an effective scheme to enhance the efficiency of optical second-order sideband (OSS) via optomechanically induced absorption (OMIA) in a double-cavity optomechanical system. In this double-cavity optomechanical configuration, the optomechanical cavity is driven by a strong control field and a weak probe pulse, while the assisted cavity is excited by another strong control field. Using experimentally achievable parameters, we identify that the present optomechanical system can create the OMIA effect and improve the efficiency of the upper OSS beyond that is achieved by employing optomechanically induced transparency (OMIT). With the aid of OMIA, we also report that the maximum efficiency and linewidth of the upper OSS peak can be modulated by the double-cavity coupling strength and the detuning of the driving field. The present proposal offers a new path to optimize optical nonlinearity and design chip-scale signal processing.

A coherently prepared Er3+-doped yttrium aluminum garnet (YAG) crystal with a four-level ionic configuration is exploited for realizing one-dimensional (1D) and two-dimensional (2D) electromagnetically induced gratings (EIGs). Owing to the probe gain induced by the incoherent pump, the diffraction efficiency of the crystal grating, especially the first-order diffraction, can be significantly improved via increasing the incoherent pumping rate or decreasing the probe detuning. The enhancement of the grating diffraction efficiency originates from the interference between the gain and phase gratings. It is also demonstrated that the diffraction of the crystal grating can be dynamically controlled via tuning the intensity and detuning of the standing-wave driving field or the concentration of Er3+ ion. More importantly, the probe energy of the diffraction side lobes around the central principle maximum is comparable to that of the first-order diffraction field for small driving intensity or large driving detuning. Our scheme may provide a possibility for the active all-optical control of optical switching, routing and storage in fiber communication wavelengths.

The electronic, optical, and photocatalytic properties of Au-adsorbed MoSi2N4 systems are predicted by first-principles calculations. Electronic structure analysis shows that the band gap is reduced from 1.89 eV (intrinsic MoSi2N4) to 0 eV (MoSi2N4–9Au). Calculation results of density of states indicate that the valence band edge is mainly contributed by the Mo 4d state, whereas the conduction band edge is contributed by both the Mo 4d and Si 3p states. As the number of adsorbed Au atoms is increased, the absorption coefficient increases from 3.0 × 104 cm−1 to 5.6 × 104 cm−1, meaning that more photons can be absorbed. Indeed, Au-adsorbed MoSi2N4 monolayer shows greater potential for applications such as water splitting and CO2 reduction based on redox potential analysis. The Au-adsorbed MoSi2N4 structures can effectively change the properties of materials, offering great potential in different fields.

We propose a scheme for realizing high-precision three-dimensional (3D) atom localization by using V-type three-level atoms in which atoms interact with a weak probe field, a weak control field together with three mutually perpendicular standing-wave fields. Our numerical results show that the precision of 3D atom localization in volumes can be improved via three-wave mixing (TWM) in the presence of the control switch field but made instead to be reduced when the TWM channel is off in absence of the switch field. As a result, assisting with TWM, a single position information of the atom in the 3D space can be achieved, and the atom can be localized in volumes that are substantially smaller than a cubic optical wavelength. The effect of spontaneously generated coherence (SGC) as well as the relative phase of the applied fields on the precision of 3D atom localization are also discussed.

The properties of two and three two-split-ring-resonators (TSRRs) are investigated in this paper, which shows a remarkable Fano resonance in the microwave frequency. In two TSRRs, the Fano resonance results from the interference between two TSRRs by conductive coupling, both experiments and numerical simulations are in good agreement. The structure shows strong magnetic dipole at the intersection of two TSRRs. In three TSRRs, the double Fano resonances can be excited and double magnetic dipoles produce at two intersections. Because of the interaction between two magnetic dipole, symmetric magnetic dipole and anti-symmetric magnetic dipole (toroidal dipole) modes are presented, respectively. An almost doubled Q factor is observed in the three TSRRs compared to the two TSRRs. In addition, we experimentally demonstrate that the double Fano resonances are sensitivity to the refractive index of background. The sensitivity changes with the change of position of detected material. The highly sensitive areas of double Fano resonances locate at two intersections. This study paves the way to excite the multiple Fano resonances. Such Fano resonance can be applied to the sensors.

We analyze the optical steady-state behaviors based on intersubband transitions in a triple quantum well structure driven coherently by a probe laser field and two control laser fields embedded in a unidirectional cavity. It is shown that the optical bistability behavior can be observed and controlled efficiently through the frequency detuning of the probe field, the intensities of two control fields, the electronic cooperation parameter, and the Fano-type interference. More interestingly, with Fano-type interference, switch from optical bistability to optical multistability or vice versa can be also controlled by adjusting the relative phase between two coherent control fields.

We propose a theoretical scheme to coherently control the transport of a single electron in an asymmetric double-quantum-dot system. The single-electron transport originates from the intrinsic interplay between the externally applied few-cycle pulse and the inter-dot tunneling. Solving the equations of motion for dot-density matrix, we reveal numerically that the current exhibits a significant dependence on the carrier-envelope phase (CEP) of the few-cycle pulse, which is similar to the magnetic flux controlled coherent transport in an Aharnov–Bohm (AB) interferometer. As a result, by varying the CEP of the pulse one can suppress or enhance the current either instantaneously or periodically. Our results illustrate the potential to utilize few-cycle pulses for excitation in quantum dot systems through the CEP control, as well as a guidance in the design for possible experimental implementations.

We analyze the absorption-dispersive properties of a weak probe laser field based on the ISBT in a triple semiconductor quantum well (SQW) structure driven coherently by two control laser fields. It is shown that the system can produce anomalous and normal dispersion regions with negligible absorption by adjusting the intensities of the control fields and the Fano-type interference. More interestingly, the dispersion can be changed between normal and anomalous simply by adjusting the relative phase between two coherent control fields due to the existence of the Fano-type interference. Thus the relative phase can be regarded as a switch to manipulate light propagation with subluminal or superluminal. In addition, the temporal and spatial dynamics of the probe laser pulse with Gaussian-type envelope are analyzed.

The visibility of ghost-interference patterns is investigated firstly based on the coherent-mode representation theory. We find that the intensity correlation function can be changed from the usually two-dimensional integral representation to a new one-dimensional summation representation. During the process of analyzing the effects from the light source's properties and the transmission area of the object imaged on the imaging visibility, it is shown that by compared with the results from the integral representation, the coherent mode representation is quite useful to understand more clearly the whole process of correlated imaging.

The theoretical analysis of the noise property is presented in a correlated imaging system. For both entangled source produced by parametric down-conversion (PDC) and classically light source, a small aperture of the imaging system makes the noise increase slightly and the resolution of the imaging signal degrade. We also show that, in PDC case, the noise is strongly influenced by the source size because of the existence of the entanglement, while the effect is not obvious in the thermal case.

We investigate two imaging schemes, lensless system and 2-f system which are used to implement ghost diffraction. It is shown that the two schemes have similar intensity fluctuation correlation functions which both realize the function of the Fourier-transform imaging, and the diffraction pattern is in agreement with that in the classical wave optics. The difference of the imaging visibility in the two systems is also discussed.

The giant enhancement of Kerr nonlinearity in a four-level inverted-Y atomic system is investigated theoretically. Compared with that generated in a generic three-level system, the Kerr nonlinearity can be enhanced by several orders of magnitude with vanishing linear absorption. The physical mechanism leading to the giant enhancement of Kerr nonlinearity is also discussed.

We investigate the enhancement of Kerr nonlinearities in an asymmetric coupled double quantum-well (CQW) by analyzing the nonlinear optical response. With the consideration of real parameters in AlGaAs-based CQWs, we indicate the possibility to obtain the giant Kerr nonlinearities with the cancellation of linear absorption simultaneously. We also reveal both analytically and numerically that under appropriate conditions a probe field with very low intensity can evolve into a stable shape-preserving waveform that propagates with a slow group velocity. The stability of such slow optical solitons is also demonstrated numerically.

We propose and analyze an efficient scheme for suppressing the absorption of a weak probe field based on intersubband transitions in a four-level asymmetric coupled quantum well (CQW) driven coherently by a probe laser field and a control laser field. We study the steady-state process analytically and numerically, and our results show that the probe absorption can be completely eliminated under the condition of Raman resonance (i.e. two-photon detuning is zero). Besides, we can observe one transparency window without requiring one- or two-photon detuning to exactly vanish. This investigation may provide a possible scheme for EIT in solids by using the CQW.

We study the spectrum of ultracold atoms on the honeycomb lattice under a constant effective magnetic field. In the tight-binding approximation, we derived the generalized Harper's equations and numerically calculate the spectrum, which has a fractal structure. For the cases with and without the next-nearest-neighbor tunneling, the graphs of spectra have different symmetries. Comparing the symmetries of the graphs of spectra, we find that next-nearest-neighbor tunneling induces symmetry breaking of the graph of spectrum.

We perform a time-dependent analysis of continuous wave (cw) four-wave mixing (FWM) in InGaAs/AlAs coupled double quantum well (CDQW) structures via intersubband transitions. By using the coupled Schrodinger-Maxwell approach, we obtain the corresponding explicit analytical expressions for the input probe and FWM-generated signal fields. We calculated the dependencies of the efficiency of the FWM-generated fields on cw pump fields and the depths of penetration into the CDQW sample. Such a nonlinear optical process may be used to generate coherent short-wavelength radiation efficiently in the CDQW solid state system.

We show that a giant Kerr nonlinearity with a relatively large cross phase modulation (CPM) phase-shift can be used for realizing polarization quantum phase gate based on the nonlinear optical response in a coupled semiconductor double quantum well (SDQW) structure via intersubband transitions.

In this letter, a efficient scheme is proposed for the quantum secret encryption and decryption implementation for quantum secret sharing protocol with trapped ions in thermal motion, in which the effective Hamiltonian does not involve the external degree of freedom and thus the scheme is insensitive to the external state, allowing it to be thermal state. The proposed scheme requires no auxiliary states to assist intermediate atomic transitions and conditional quantum dynamics for quantum phase flip and quantum state diffusion. Besides, secret transmission using entanglement swapping also has been presented.

We propose a practical scheme for implementing two-dimension quantum dense coding (QDC) between three parties through manipulating three ions confined in microtraps addressed by microwaves and assisted by a magnetic field gradient. The ions in our scheme are not required to be strictly cooled to the vibrational ground state because single-qubit and multi-qubit operations are made via Ising terms, in which the vibrational modes of the ions remain unchanged throughout the scheme, rendering our scheme robust to the heating of the ions. We also present the detailed steps and parameters for implementing the three-party QDC experimentally and show that the proposed scheme is within the current techniques of ion-trap experiments., Comment: 6 pages, 2 figures, accepted by J. Phys. B: At. Mol. Opt. Phys

In this letter, a procedure is proposed for reconstructing the motional quantum state of N trapped ions. Unlike other previous schemes, the present scheme works in the dispersive regime in the presence of dissipation. In our scheme, we show that it is possible to directly measure the quasiprobability distribution function corresponding to the motional coherent state in a trapped-ion system subjected to dissipation. We also provide an example of a motional Schrödinger cat state reconstruction to exemplify our procedure.

We present an alternative scheme to prepare entangled states of multiple trapped ions in thermal motion. In this scheme the vibrational degrees of freedom are only regarded as intermediate states and the ions exchange energy via the mediation of the vibration of the vibrational mode in coupling processes. The scheme is insensitive to both the initial vibrational state and heating if the system remains in the Lamb–Dicke regime. Since the effective Rabi frequency has a small dependence on the vibrational quantum number, the heating will have no direct effect on the internal state evolution. The scheme can also be used for the storage of entangled states.

We proposed a scheme to generate a multi-component squeezed coherent states with arbitrary coefficients on a line in phase space for multiple trapped ions radiated by a single standing-wave laser whose carrier frequency is tuned to the ions transition. In the scheme each ion does not need to be exactly positioned at the node of the standing wave. Furthermore, our scheme may allow the generation of a multi-component squeezed coherent states with large mean phonon number in a fast way by choosing a suitable laser intensity, which is important in view of de-coherence processes.

We report experimental observation of lasing on surface states, in the form of standing waves at the termination of a defect-free photonic crystal on top of vertical-cavity surface-emission lasers. Direct images of lasing modes at the truncated periodic potential, along one side of a square lattice, are demonstrated by collecting near-field radiation patterns, as well as in numerical simulations. Our results provide a step toward realizing surface and edge states in optical cavities.

We propose and analyze an effective scheme to generate hyper-Raman scattering via inhibiting electromagnetically induced transparency (EIT) in a monolayer graphene under a magnetic field. By solving the Schrödinger-Maxwell formalism, we derive explicitly analytical expressions for linear susceptibility, nonlinear susceptibility, and generated Raman electric field under the steady-state condition. Based on dressed-state theory, our results show a competition between EIT and hyper-Raman scattering, and the hyper-Raman process is totally dominant when multiphoton destructive interference is completely suppressed.

We propose and analyze an efficient way to detect the terahertz (THz) signal in a magnetized graphene system via electromagnetically induced transparency. Such a scheme for THz signal detection mainly relies on the measurement of probe transmission spectra, in which the behaviors of a weak-probe transmission spectra can be controlled by switching on/off the THz signal radiation. Taking into account the tunable optical transition frequency between the Landau levels in graphene, our analytical results demonstrate that a broad frequency bandwidth of the THz signal radiation, ranging from 0.36 to 11.4 THz, can be inspected and modulated by means of an external magnetic field. As a consequence, the proposed magnetized graphene system performs a striking potential to utilize quantum interference in the design of optical solid-state devices.

We investigate the high-order harmonic generation (HHG) in a semiconductor quantum dot (SQD) and metallic nanorod (MNR) complex driven by a moderate intensity (10(12) W/cm(2)) frequency-chirped Gaussian few-cycle pulse. Our numerical results indicate that the cutoff energy of the HHG can be controlled by optimizing the shape of the MNR and surface-to-surface distance between the SQD and the MNR. We also show that the extreme ultraviolet supercontinuum harmonics (25 eV maximal photon energy) and isolated ultrashort pulses (2.67-4.36 fs FWHM) are achievable.

Tunneling-induced quantum interference experienced by an incident probe in the asymmetric double AlGaAs/GaAs quantum well (QW) structure can be modulated by means of an external control light beam and the tunable coupling strengths of resonant tunneling. These phenomena can be exploited to devise a novel intracavity medium to control Goos-Hänchen (GH) shifts of a mid-infrared probe beam incident on a cavity. For a suitably designed QW structure, our results show that maximum negative shift of 2.62 mm and positive shift of 0.56 mm are achievable for GH shifts in the reflected and transmitted light.

We conducted a theoretical investigation of the optical steady-state behavior in N four-level Y-type atoms driven coherently by a probe laser and a single elliptically polarized field (EPF) by means of a unidirectional ring cavity. It was found that the optical bistability can be observed for a wide regime of frequency detuning of the probe field, intensity of the EPF, and the atomic cooperation parameter. Interestingly, in principle the optical steady-state behavior can be switched from optical bistability to multistability or vice versa by adjusting the phase difference between two components of the polarized electric field of the EPF if the perfect spontaneously generated coherence of atoms is included. Our results illustrate the potential to utilize EPF for all-optical switching in atomic systems through the phase control, as well as provide guidance in the design for possible experimental implementations.

We propose a scheme for controlling the coherent transport of a single electron through a closed three-level structure in coupled quantum dots. The coherent transport is externally controlled by applying a weak few-cycle pulse with an adjustable carrier-envelope phase (CEP). It is revealed numerically that there exists a significant dependence of the electron transport on the CEP. Our results illustrate the potential to utilize few-cycle pulses for the excitation in coupled quantum dot systems through control of the CEP, as well providing guidance in the design for possible experimental implementations.

We analyze the hybrid absorptive-dispersive optical bistability (OB) behavior in an open Λ-type three-level atomic system by using a microwave field to drive the hyperfine transition between two lower states, along with the consideration of incoherent pumping and spontaneously generated coherence. Different from the closed system, we show that the bistable threshold intensity and related hysteresis loop can be controlled by adjusting the ratio between atomic injection and exit rates. More interestingly, the appearance and disappearance of OB can be transformed mutually by varying the relative phase of three coherent fields under the condition of a strong spontaneously generated coherence. The manipulation of OB behavior through the intensity of the microwave field and the atomic cooperation parameter is also analyzed.

We show the formation of bright and dark slow optical solitons based on intersubband transitions in a semiconductor quantum well (SQW). Using the coupled Schrodinger-Maxwell approach, we provide both analytical and numerical results. Such a nonlinear optical process may be used for the control technology of optical delay lines and optical buffers in the SQW solid-state system. With appropriate parameters, we also show the generation of a large cross-phase modulation (XPM). Since the the intersubband energy level can be easily tuned by an external bias voltage, the present investigation may open the possibility for electrically controlled phase modulator in the solid-state system.