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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 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]

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]

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]

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]

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]

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]

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]

Photon blockade (PB) is an important quantum phenomenon in cavity quantum electrodynamics (QED). Here, we investigate the PB effect in the simplest cavity QED systems (one cavity containing first a single atom and then two atoms), where only the atoms are weakly driven. Via the analytical calculation and numerical simulation, we show that the strong PB can be generated even with the weak-coupling regime at the total resonance. This blockade is ascribed to the two-photon absorption, which is fundamentally different from the conventional and unconventional blockade mechanisms. Therefore, our study provides an alternative approach to produce the PB in the atom-driven cavity QED system.

We present a proposal to enhance the cross-Kerr coupling between the cavity and the mechanical oscillator significantly. Specifically, the periodic modulation of the mechanical spring constant induces strong mechanical parametric amplification, which leads to the cross-Kerr nonlinear enhancement. Also, we discuss its application in photon-phonon blockade and phonon-number measurement. We find that under the strong cross-Kerr coupling condition, not only the photon-phonon blockade effect is dramatically enhanced but also different phonon number is clearly distinguished. Our results offer an alternative approach to perform quantum manipulation between photon and phonon.

Quantum estimation of electrical charge is investigated by using nonlinear optomechanical interaction. Due to the light-matter decoupling at one mechanical period, we need to consider only the cavity state, meaning that no direct access to the oscillator state is required. It is shown that the charge sensitivity can be greatly improved by enhancing optomechanical coupling. Further, we find that our theoretical result can surpass the sensitivity obtained from electrical measurements.

We investigate the electromagnetically induced grating (EIG) in a quantum dot-metal nanoparticle (QD-MNP) hybrid system. The EIG can be controlled and improved by the surface plasmon effect and the interdot tunneling effect between quantum dots. By manipulating the tunneling effect and the QD-MNP distance, not only the first-order diffraction intensity of the grating can be efficiently enhanced, but also the EIG can be switched from the absorption grating to the gain grating. Almost two times the first-order diffraction efficiencies can be achieved in the gain gratings compared with the absorption gratings.

The mechanical squeezing can be used to explore quantum behavior in macroscopic system and realize precision measurement. Here we present a potentially practical method for generating strong squeezing of the mechanical oscillator in an electromechanical system. Through the Coulomb interaction between a charged mechanical oscillator and two fixed charged bodies, we engineer a quadratic electromechanical Hamiltonian for the vibration mode of mechanical oscillator. We show that the strong position squeezing would be obtained on the currently available experimental technologies.

We propose a scheme to generate the entangled state of two Lambda-type three-level atoms trapped in distant cavities by using interference of polarized photons. Two possible spontaneous emission channels of each excited atom result in a coherent superposition of the states of two atoms. The subsequent detection of the different polarized photons reveals that both atoms are in different ground states, but an interference effect prevents us from distinguishing which atom is in which ground state; the atoms are thus entangled. In comparison with the original proposal of interference-induced entanglement [C. Cabrillo, J. Cirac, P. Garcia-Fernandez, and P. Zoller, Phys. Rev. A 59, 1025 (1999)]], in our scheme the weakly driven condition is not required, and the influence of atomic excitement and atomic recoil on the entanglement fidelity can be eliminated.