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We investigate the use of the cross-Kerr nonlinearity to realize strong photon blockade in a weakly driven, three-mode system. The results show that the conventional photon blockade induced by the strong nonlinearities and the unconventional photon blockade induced by quantum interference effects exist in our system. In particular, we find that the CPB only appears in the strong cross-Kerr coupling regime, while the UPB can occur in the weak or strong cross-Kerr coupling regime. For the strong cross-Kerr nonlinearities, both CPB and UPB exhibit strong antibunching features. Furthermore, the switch between CPB and UPB can be achieved with different detunings. Our work paves the way to study two different physical mechanisms behind CPB and UPB. [ABSTRACT FROM AUTHOR]

Abstract: The dynamic evolution of a Λ system coupled by two strong coherent fields is investigated by taking spontaneously generated coherence (SGC) into account. By numericaly simulation, it is shown that the relative phase of the two coherent fields affects significantly the time scale to the coherent population trapping state. In addition, an analytical expression to the evolution rate which is consistent with the numerical results is given. [Copyright &y& Elsevier]

The steady-state nonlinear behavior in a ring cavity based on a Λ-type atomic model is investigated. It is shown that, due to the existence of strong spontaneously generated coherence, optical bistability still can be realized even if both coherent fields in resonance with the medium. Moreover, the appearance or disappearance of bistability can be controlled by adjusting the relative phase between the two coherent fields. When the probe field is not resonant, it is found that the threshold intensity for producing bistability is very sensitive to the relative phase, and bistability and multistablity can transform mutually by adjusting the relative phases. [Copyright &y& Elsevier]

We investigate the coherent control of spectra effects with chirped femtosecond laser pulse propagation in a two-level-atom medium. It is found that the spectral feature depends crucially on the sign and magnitude of the initial chirp rate. For small chirp rate, blueshift or redshift of the spectrum can occur depending on the sign of the chirp. However, for relative large chirp rate, the medium can become transparent to positive chirped pulse, whereas in the case of negative chirped pulse, higher spectral components can be produced even for small area pulses. [Copyright &y& Elsevier]

The effect of spontaneously generated coherence (SGC) on the pump–probe response of a nearly degenerate Λ system is investigated by taking into account the dephasing of the low-frequency coherence. It is found, in the case of small dephasing, that instead of electromagnetically induced transparency (EIT) at resonance, electromagnetically induced absorption (EIA) can occur due to the effect of SGC. We also study the effect of relative phase between the two applied fields and find that EIA and EIT can transform mutually by adjusting the relative phase. [Copyright &y& Elsevier]

Spontaneous emission can create coherence in a ladder-type three-level atom with equispaced levels, subject to the condition that the atomic dipole moments are nonorthogonal. We study the effects of this kind of coherence on the steady-state population inversion in the atomic system. We show that the population inversion can be greatly enhanced on one of the optical transitions due to the spontaneous emission-induced coherence. Furthermore, we find, within suitable parameters regions, that such coherence can also lead to unexpected population inversion on both of the optical transitions. [Copyright &y& Elsevier]

The nonreciprocity between two signal fields is regarded as a key function in future quantum networks and modern communication technologies. Here, we theoretically propose a scheme of nonreciprocal devices between signal fields in two different arbitrarily frequency domains in a hybrid cavity opto-electromechanical system. The model consists of a microwave cavity and an optical cavity, respectively, coupled with two different mechanical oscillators, which are coupled together by the tunable Coulomb interaction and driven by the external electrical fields. We study the nonreciprocal response between two different frequency fields. Nonreciprocal transmission is based on multichannel quantum interference to break time-reversal symmetry. The perfect nonreciprocity is shown in the certain conditions. By adjusting the Coulomb interaction, the phase differences, and strength of the electrically driven fields on the mechanical oscillators, we find that nonreciprocity can be modulated and even transformed into perfect nonreciprocity and reciprocity. These results provide a new insight into the design of nonreciprocal devices and present the potential applications in quantum information processing and quantum networks. [ABSTRACT FROM AUTHOR]

We present the most prominent features in two-colour coherent control of high-order harmonic generation using a strongly driven two-level atom model, which are known to generate high harmonics as well as hyper-Raman lines with a plateau and a cut-off. Furthermore, for one laser field case, we find, when the hyper-Raman lines are located at the position of the high harmonics, that the high harmonics are strongly enhanced due to the interference effect between the high harmonics and the hyper-Raman lines. Within these conditions, by combining the laser field with another much weaker laser field, we show plentiful and strong high harmonics in the light spectrum of the driven atomic system. [ABSTRACT FROM AUTHOR]

The steady-state population behaviour in a laser driven V-type system has been analysed. The effects of spontaneous emission-induced coherence and of the relative phase of the two coherent driving fields are considered in detail. A large and unexpected population inversion is found on one of the optical transitions due to these coherent effects. [ABSTRACT FROM AUTHOR]

We theoretically study the nonlinear optical phenomena including optical stability state and four-wave mixing (FWM) process in a hybrid opto-electromechanical system with the cross-Kerr (CK) effect. The hybrid system consists of an optomechanical cavity in which the cross-Kerr (CK) effect and Coulomb interaction are simultaneously introduced by the CK medium and the mechanical resonator capacitively coupling to an external circuit, respectively. The CK interaction induces a tristability behavior of the mean intracavity photon number, which can be modulated by the strength of the CK effect and electrically controlled by the voltage on the capacitor. In addition, we give the effects of the optomechanical, CK, and Coulomb coupling strengths on the FWM of the output field. The results show that the voltage can be employed to electrically engineer the optical nonlinear phenomena. [ABSTRACT FROM AUTHOR]

The future quantum networks will require reversible coherent conversion and modulation between microwave and optical photons to link the quantum information-processing ability of microwave and long-distance distribution ability of optical photons. Here, we present a scheme of bi-directional phase controllable four-wave mixing (FWM) between microwave and optical fields in the hybrid opto-electromechanical system. As an intermediate interface, a nanomechanical resonator optomechanically couples both optomechanical cavities in the optical and microwave frequency domains by the radiation pressure forces. We can find the four peaks of FWM, study the effects of the phases of the driven fields on the total, absolute, and cross correlation FWMs, and achieve the laws of phase control FWM based on quantum interference. In particular, we believe that such a hybrid opto- and electro-mechanical device incorporating highly coherent and compact mechanical elements on a chip has some potential functions for electro-optic modulation. We expect that such a modulator will have a broad range of applications including in optical communications and further quantum networks. [ABSTRACT FROM AUTHOR]

Pulsed Nd:YAG (532 nm) and Excimer (248 nm) lasers were employed to produce freestanding, two-dimensional (2D), carbon nanosheets (CNSs) from naphthalene, through laser-induced exfoliation. The polymer-to-carbon transition was investigated in terms of laser wavelengths, fluences, as well as target preparations. Continuous and porous CNSs of several nanometers in thickness and micrometers in size were obtained from 532 and 248 nm pulsed laser exfoliation of spin-coated naphthalene films, respectively. The porous morphology is ascribed to the photon-induced dissociation of chemical bonds dominated in 248 nm laser interaction with ablated naphthalene. With the increase of laser fluences from 1 to 5 J cm −2 , amorphous carbon and ultrathin CNS structures were obtained in sequence. This work revealed a general mechanism of producing 2D structured carbon materials from pulsed laser exfoliation. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the steady-state optical bistability behavior in a three-level Λ-type atomic system closed by a microwave field under the condition that the applied fields are in resonance with corresponding atomic transitions. It is shown that the bistable hysteresis cycles can be controlled by both the amplitude and the phase of the microwave field. [Copyright &y& Elsevier]

We investigate the optical bistability (OB) behavior of a nearly equispaced ladder-type three-level atomic system contained in a unidirectional ring cavity. We consider the three-level atoms under conditions that the atomic dipole moments are nonorthogonal so that the effect of spontaneously generated coherence (SGC) is important. We find that the SGC effect significantly affects the OB behavior of such system. Within certain parameter range, OB can be realized due to the SGC effect. The bistable hysteresis cycle becomes wider with the enhancement of SGC effect. Furthermore, such system is much sensitive to the relative phase between the coupling and probe fields. This property makes it possible to switch between bistability and multistability via adjusting the relative phase. [Copyright &y& Elsevier]

We present a scheme for the quantum storage of single photons using electromagnetically induced transparency (EIT) in a low-finesse optical cavity, assisted by state-selected spontaneous atomic emission. Mediated by the dark mode of cavity EIT, the destructive quantum interference between the cavity input–output channel and state-selected atomic spontaneous emission leads to strong absorption of single photons with unknown arrival time and pulse shapes. We discuss the application of this phenomenon to photon counting using stored light. [ABSTRACT FROM AUTHOR]

We present a scheme of reversible waveform conversion between microwave and optical fields in the hybrid opto-electromechanical system. As an intermediate interface, nanomechanical resonator optomechanically couples both optomechanical cavities in the optical and microwave frequency domains. We find the double-optomechanically induced transparency and achieve coherent signal waveform bi-directional transfer between microwave and optical fields based on quantum interference. In addition, we give an analytical expression of one-to-one correspondence between the microwave field and the optical output field, which intuitively shows the reversible waveform conversion relationship. In particular, by numerical simulations and approximate expression, we demonstrate the conversion effects of the three waveforms and discuss the bi-directional conversion efficiency and the bandwidth. such a hybrid opto- and electro-mechanical device has significant potential functions for electro-optic modulation and waveform conversion of quantum microwave-optical field in optical communications and further quantum networks. [ABSTRACT FROM AUTHOR]

We propose a scheme to implement electrically controlled quantum memory based on vacuum-induced transparency (VIT) in a high-Q tunable cavity, which is capacitively coupled to a mechanically variable capacitor by a charged mechanical cavity mirror as an interface. We analyze the changes of the cavity photons arising from vacuum-induced-Raman process and discuss VIT in an atomic ensemble trapped in the cavity. By slowly adjusting the voltage on the capacitor, the VIT can be adiabatically switched on or off, meanwhile, the transfer between the probe photon state and the atomic spin state can be electrically and adiabatically modulated. Therefore, we demonstrate a vacuum-induced quantum memory by electrically manipulating the mechanical mirror of the cavity based on electromagnetically induced transparency mechanism. [ABSTRACT FROM AUTHOR]

We investigate the coherence trapping of a two-level atom transversally interacting with a reservoir with a photonic band-gap structure function. We then focus on the multipartite entanglement dynamics via genuinely multipartite concurrence among N independent atoms each locally coupled with its own reservoir. By considering the Lorentzian width and the system size, we find that for the resonant and near-resonant conditions, the increase of Lorentzian width and the decrease of system size can lead to the occurrence of coherence trapping and entanglement trapping. By choosing the multipartite GHZ state as atomic initial state, we show that the multipartite entanglement may exhibit entanglement sudden death depending on the initial condition and the system size. In addition, we also analyze how the crossover behaviors of two dynamical regimes are influenced by the Lorentzian width and the weight ratio, in terms of the non-Markovianity. [ABSTRACT FROM AUTHOR]

In this paper, we propose a scheme to realize electrically controlled quantum memories in a cavity and electro-mechanical system. By assisting with a constant weak optical field into the high- $Q$ cavity, the electrical manipulations of the dark-state polariton and the group velocity of light are derived. The storage and retrieval of the photon state can be realized and optimized by sending the optimal voltage waveforms in the electric circuit, respectively. In addition, the storage efficiency and the experimental feasibility are discussed. The cavity-induced quantum memory scheme driven by the electric field here has potential applications in future integration and miniaturization of optical information processing devices. [ABSTRACT FROM AUTHOR]

We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity. It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region, which has been known as the positive Doppler effect on optical bistability. In addition, we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type. [ABSTRACT FROM AUTHOR]

We theoretically investigate the high-order harmonic generation from the hydrogen atom driven by the laser pulses with the durations less than the optical cycle. It is found that the switching term of the laser field may have an obvious influence on the cutoff, intensity or plateau structure of the high-order harmonic spectrum. Generally speaking, the switching term can shorten the cutoff of the high-order harmonic spectrum for a relatively longer pulse and extend the cutoff for a relatively shorter pulse. [ABSTRACT FROM AUTHOR]

Black thermal control blankets have been widely used in spacecraft for eliminating stray light around high-resolution optical instruments. However, the limited absorption in visible light range, the fast degradation upon hyperthermal atomic oxygen (AO) in low Earth orbit (LEO), and the poor adhesion of black coatings with substrate confined their applications into board solar spectrum and multi-layer interface engineering. In this work, a nanocomposite polyimide film containing a trisilanolphenyl POSS, a dye of solvent black 34, and a carbon black of CABOT M800 has been designed. With an ingredient of 20 wt% POSS, 5 wt% dye, and 10 wt% carbon black, the nanocomposite polyimide film PPIBC10 exhibited an ultra-low transmittance near zero in the range 200–2000 nm, a low reflectance below 5% in UV range and below 2% in VIS-IR range, and a low erosion yield of 0.49 ± 0.11 × 10−24 cm3 atom−1 upon a 2.27 × 1020 atoms cm−2 hyperthermal AO exposure, with an absorptance of 0.983, an emissivity of 0.86, and a coefficient of thermal expansion of 20 ppm oC−1. SEM and XPS analysis indicated that a uniform SiO x passivating network was formed on surface upon the hyperthermal AO exposure. The tensile strength decreased with increasing additives, and kept stable upon the AO exposure, for there was only sub-micrometer in erosion depth. The thermal expansion coefficients of the nanocomposite films are comparable to that of Kapton, which benefits interface engineering. The small granularity of tens of micrometers and good solubility in poly(amic acid) of additives POSS, dye, and carbon black benefit potential manufacture. This study suggests an ultra-black AO durable polyimide film for potential applications in LEO. Image 1 • A nanocomposite polyimide film was designed with additives of a POSS, a dye, and a carbon black in poly(amic acid). • Bulk-phase black dye and carbon black reinforcements for ultra-low transmittance and reflectance in solar spectrum. • Bulk-phase POSS reinforcement for atomic oxygen resistance. • Comparable coefficient of thermal expansion to Kapton. • Small-granularity and soluble additives in polar solvent. [ABSTRACT FROM AUTHOR]

We present an efficient method for quantum estimation of gravitational acceleration in a modulated optomechanical system. We use the squeezed mechanical mode, which could potentially enhance the optomechanical interaction between cavity field and mechanical oscillation into the strong-coupling regime. We show that the strong optomechanical coupling can significantly improve the measurement sensitivity of gravitational acceleration. The proposed scheme can provide a platform for further investigations on precision measurement of gravitational acceleration. [ABSTRACT FROM AUTHOR]