Quantum Optical Devices Research Articles

Laser frequency stabilization in sub-nanowatt level using nanofibers

We introduce a novel scheme which combines conventional Doppler dichroic atomic vapor laser lock (DAVLL) and nanofiber techniques for realizing frequency stabilization with sub-nanowatt laser power. The dependences of DAVLL signal on the total incident power of probe light and the quantification magnetic field amplitude indicate that the power for frequency stabilization could be minimized to only 15 pW. To evaluate the frequency stability of the locked laser, we calculate the Allan standard deviation, which shows that the relative frequency stability could reach 10−10 level at 10 s. This frequency stabilization scheme paves the road for future quantum optical device integration.

Entanglement Dynamics of Two Atoms in a Double Damping Jaynes-Cummings System**Supported by the National Natural Science Foundation of China under Grant No. 11504218, and the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices No. KF201704

The entanglement between two stationary qubits is a kind of valuable quantum resources in quantum information or quantum network. This paper investigates the time evolution of the entanglement between two atoms, which are initially prepared in the Bell states and each of which interacts with its own cavity field in the identical and non-identical double damping Jaynes-Cummings (J-C) system. It mainly considers the effect of the atomic spontaneous decay Γ and the decay of cavity field κ on the two-qubit entanglement in such system. While causing the decay of entanglement, Γ and κ can also play a positive role in the entanglement evolution, which may imply a way to better control and maintain the entanglement. What is more, the rules governing the transfer of entanglement between two-qubit subsystems in strong coupling regime are finally studied by taking Γ and κ into consideration.

Double optomechanically induced transparency and absorption in parity-time-symmetric optomechanical systems

We explore the optomechanically induced transparency (OMIT) in a parity-time-symmetric ($\mathcal{PT}$-symmetric) optomechanical system (OMS) in which the mechanical oscillator is coupled to another one via the Coulomb interaction. Calculating the transmission rate of the probe field, we find that double optomechanically induced absorption (OMIA) can be observed by modulating the Coulomb coupling strength with zero gain rate of the active cavity. The absorption window for the system in the $\mathcal{PT}$-symmetry-broken phase is deeper than that in other phases due to the strong field localization. When the gain rate is not zero, the output field of the system exhibits double inverted OMIT. Both splits of the double OMIA and double OMIT depend linearly on the strength of the Coulomb interaction. The inverted OMIT can also be changed into an absorption window and the system can achieve perfect absorption by modulating the Coulomb coupling strength. The transmission light at the double inverted OMIT is always fast light and the transmission light at $\ensuremath{\delta}={\ensuremath{\omega}}_{m}$ is always of slow light, independent of the phase the system in (the $\mathcal{PT}$-symmetry phase or the $\mathcal{PT}$-symmetry-broken phase). The absolute value of the group delay at $\ensuremath{\delta}={\ensuremath{\omega}}_{m}$ can be manipulated by controlling the strength of the Coulomb interaction. These observations provide us with a tool to control light propagation which might have potential application in quantum optical devices and quantum information networks.

High-Q integrated photonic microresonators on 3C-SiC-on-insulator (SiCOI) platform.

We report a high-quality 3C-silicon carbide (SiC)-on-insulator (SiCOI) integrated photonic material platform formed by wafer bonding of crystalline 3C-SiC to a silicon oxide (SiO2)-on-silicon (Si) substrate. This material platform enables to develop integrated photonic devices in SiC without the need for undercutting the Si substrate, in contrast to the structures formed on conventional 3C-SiC-on-Si platforms. In addition, we show a unique process in the SiCOI platform for minimizing the effect of lattice mismatch during the growth of SiC on Si through polishing after bonding. This results in a high-quality SiCOI platform that enables record high Qs of 142,000 in 40 µm radius SiC microring resonators. The resulting SiCOI platform has a great potential for a wide range of applications in integrated optics, including nonlinear optical devices, quantum optical devices, and high-power optical devices.

Enabling Lasing Action in Hybrid Atomic–Nanophotonic Integrated Structures

AbstractThe incorporation of neutral atoms in nanophotonic structures offers significant potential to realize novel quantum optical devices. Here, the possibility of creating low‐threshold integrated lasers in hybrid systems based on coupling room‐temperature atomic gases with both dielectric and metallic nanophotonic systems is investigated. Two different classes of devices resulting from incorporating an optically pumped Rb–ethane mixture in a dielectric ring resonator and a plasmonic lattice are studied. It is shown that the combination of the optical gain provided by the atomic vapor, along with the unique field‐confinement properties of nanophotonic structures, enables the generation of coherent radiation, that is, laser light, at moderate power levels. In addition, general design guidelines for these hybrid nanophotonic lasers are provided. These results pave the way toward a novel class of active nanophotonic and metamaterial systems.

Plasmon-Enhanced Generation of Nonclassical Light

Strong light-matter interactions enabled by surface plasmons have given rise to a wide range of photonic, optoelectronic and chemical functionalities. In recent years, the interest in this research area has focused on the quantum regime, aiming to developing ultra-compact nanoscale instruments operating at the single (few) photon(s) level. In this perspective, we provide a general overview of recent experimental and theoretical advances as well as near-future challenges towards the design and implementation of plasmon-empowered quantum optical and photo-emitting devices based on the building blocks of nanophotonics technology: metallo-dielectric nanostructures and microscopic light sources.

Tripartite continuous-variable entanglement of NOPA system**Projected supported by the National Natural Science Foundation of China (Grant No. 11504074) and the Science Fund from the State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University, Shanxi, China (Grant No. KF201601).

We investigate the fundamental limits to the achievable tripartite continuous-variable (CV) entanglement criterion of a generalized V1 criterion. Our numerical simulation results show that the non-degenerate eigenvalues do effect the performances of the estimated minimum variances. From below the threshold to above the threshold, with the increase of the pump parameter, the tripartite CV entanglement gradually disappears. The different off-diagonal elements seriously distort the weights for entanglement. We can obtain a good tripartite CV entanglement by appropriately controlling the values of off-diagonal elements εij.

Tunable Resonance Coupling in Single Si Nanoparticle-Monolayer WS2 Structures.

Two-dimensional semiconducting transition metal dichalcogenides (TMDCs) are extremely attractive materials for optoelectronic applications in the visible and near-infrared range. Coupling these materials to optical nanocavities enables advanced quantum optics and nanophotonic devices. Here, we address the issue of resonance coupling in hybrid exciton-polariton structures based on single Si nanoparticles (NPs) coupled to monolayer (1L)-WS2. We predict a strong coupling regime with a Rabi splitting energy exceeding 110 meV for a Si NP covered by 1L-WS2 at the magnetic optical Mie resonance because of the symmetry of the mode. Further, we achieve a large enhancement in the Rabi splitting energy up to 208 meV by changing the surrounding dielectric material from air to water. The prediction is based on the experimental estimation of TMDC dipole moment variation obtained from the measured photoluminescence spectra of 1L-WS2 in different solvents. An ability of such a system to tune the resonance coupling is realized experimentally for optically resonant spherical Si NPs placed on 1L-WS2. The Rabi splitting energy obtained for this scenario increases from 49.6 to 86.6 meV after replacing air by water. Our findings pave the way to develop high-efficiency optoelectronic, nanophotonic, and quantum optical devices.

Spectral features of the tunneling-induced transparency and the Autler-Townes doublet and triplet in a triple quantum dot

We theoretically investigate the spectral features of tunneling-induced transparency (TIT) and Autler-Townes (AT) doublet and triplet in a triple-quantum-dot system. By analyzing the eigenenergy spectrum of the system Hamiltonian, we can discriminate TIT and double TIT from AT doublet and triplet, respectively. For the resonant case, the presence of the TIT does not exhibit distinguishable anticrossing in the eigenenergy spectrum in the weak-tunneling regime, while the occurrence of double anticrossings in the strong-tunneling regime shows that the TIT evolves to the AT doublet. For the off-resonance case, the appearance of a new detuning-dependent dip in the absorption spectrum leads to double TIT behavior in the weak-tunneling regime due to no distinguished anticrossing occurring in the eigenenergy spectrum. However, in the strong-tunneling regime, a new detuning-dependent dip in the absorption spectrum results in AT triplet owing to the presence of triple anticrossings in the eigenenergy spectrum. Our results can be applied to quantum measurement and quantum-optics devices in solid systems.

Theoretical analysis of new optical microcavity

Optical microcavity can confine light into a small volume by resonant recirculation. Devices based on optical microcavities are already indispensable for a wide range of applications and studies. They not only apply to traditional optics, but also have broad application prospects in quantum information and integrated optoelectronic chips. In quantum optical devices, microcavity can cause atoms or quantum dots to emit spontaneous photons in a desired direction or can provide an environment where dissipative mechanisms such as spontaneous emission are overcome so that quantum entanglement of radiation and matter is possible. For better application in quantum communication, optical microcavity needs to have a high quality factor and a low mode volume. Considering the beam coupling, spot shape and experimental production and others, the Fabry-Perot (F-P) microcavity has been widely applied to the field of optoelectronics. However, the Q-factor of the F-P microcavity is generally low, and the mode volume is large, so it needs to be improved.In addition, high Q-factor microcavity can also play a large role in detecting particles and biological macromolecules.In this paper, through the theory of wave optics, the eigenmodes of a new type of cone-top cylindrical optical micro-cavity are analyzed, and the resonant wavelength expression of the resonant cavity is obtained. We discuss the effects of the top mirror angle on the resonator performance and application of COMSOL simulation software to verify the proposed cone-top cylindrical microcavity. The optimized design and simulation results show that the quality factor of the new resonator can be increased by 22.4% to 49928.5 and the effective mode volume of the resonator can be reduced by 47.8% compared with the traditional parallel resonator. In this case, the corresponding new cavity length is 4.51 μm and the diameter is 3.13 μm. In this article its fabrications are also discussed.

Bistable Topological Insulator with Exciton-Polaritons.

The functionality of many nonlinear and quantum optical devices relies on the effect of optical bistability. Using microcavity exciton-polaritons in a honeycomb arrangement of microcavity pillars, we report the resonance response and bistability of topological edge states. A balance between the pump, loss, and nonlinearity ensures a broad range of dynamical stability and controls the distribution of power between counterpropagating states on the opposite edges of the honeycomb lattice stripe. Tuning energy and polarization of the pump photons, while keeping their momentum constant, we demonstrate control of the propagation direction of the dominant edge state. Our results facilitate the development of practical applications of topological photonics.

Controlling the Optical Response of 2D Matter in Standing Waves

There is a major development unfolding in photonic technology that promises to impact optical data processing, spectroscopy, and nonlinear/quantum optics. This new direction relates to plasmonics, metamaterials and coherent optics. It exploits the difference in manifestations of optical properties of thin films in traveling waves and standing waves. In standing waves, “coherent control” of the energy exchange between incident and scattered waves leads to new technological opportunities including single photon gates, 100 THz all-optical modulators, sophisticated spectroscopy techniques that can for example distinguish different multipole contributions to absorption and quantum optical devices. We provide an overview of the rapidly growing body of work on the optics of films and metasurfaces in coherent light fields.

Optomechanically induced absorption in parity-time-symmetric optomechanical systems

We explore the optomechanically induced absorption (OMIA) in a parity-time- ($\mathcal{PT}$-) symmetric optomechanical system (OMS). By numerically calculating the Lyapunov exponents, we find out the stability border of the $\mathcal{PT}$-symmetric OMS. The results show that in the $\mathcal{PT}$-symmetric phase the system can be either stable or unstable depending on the coupling constant and the decay rate. In the $\mathcal{PT}$-symmetric broken phase the system can have a stable state only for small gain rates. By calculating the transmission rate of the probe field, we find that there is an inverted optomechanically induced transparency (OMIT) at $\ensuremath{\delta}=\ensuremath{-}{\ensuremath{\omega}}_{M}$ and an OMIA at $\ensuremath{\delta}={\ensuremath{\omega}}_{M}$ for the $\mathcal{PT}$-symmetric optomechanical system. At each side of $\ensuremath{\delta}=\ensuremath{-}{\ensuremath{\omega}}_{M}$ there is an absorption window due to the resonance absorption of the two generated supermodes. Comparing with the case of optomechanics coupled to a passive cavity, we find that the active cavity can enhance the resonance absorption. The absorption rate at $\ensuremath{\delta}={\ensuremath{\omega}}_{M}$ increases as the coupling strength between the two cavities increases. Our work provides us with a promising platform for controlling light propagation and light manipulation in terms of $\mathcal{PT}$ symmetry, which might have potential applications in quantum information processing and quantum optical devices.

Optical and spin-optical superpositions modulated by Aharonov–Bohm effect

Generation of Aharonov–Bohm (AB) phase has achieved a state-of-the-art in mesoscopic systems with manipulation and control of the AB effect. The possibility of transfer information encoded in such systems to nonclassical states of light increases the possible scenarios where the information can be manipulated and transferred. In this paper, we propose a quantum transfer of the AB phase generated in a spintronic device, a topological spin transistor (TST), to an quantum optical device, a coherent state superposition in high-Q cavity and discuss optical and spin-optical superpositions in the presence of an AB phase. We demonstrate that the AB phase generated in the TST can be transferred to the coherent state superposition, considering the interaction with the spin state and the quantum optical manipulation of the coherent state superposition. We show that these cases provide examples of two-qubit states modulated by AB effect and that the phase parameter can be used to control the degree of rotation of the qubit state. We also show under a measurement on the spin basis, an optical one-qubit state that can be modulated by the AB effect. In these cases, we consider a dispersive interaction between a coherent state and a spin state with an acquired AB phase and also discuss a dissipative case where a given Lindblad equation is achieved and solved.

Performance analysis of quantum access network using code division multiple access model**Project supported by the National Natural Science Foundation of China (Grant Nos. 61475099 and 61102053), the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices (Grant No. KF201405), the Open Fund of IPOC (BUPT) (Grant No. IPOC2015B004), and the Program of State Key Laboratory of Information

A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of the code. Recently, the chaotic phase shifters were proposed to guarantee the orthogonality by different chaotic signals and spread the spectral content of the quantum states. In this letter, we propose to implement the code division multiple access quantum network by using chaotic phase shifters and synchronization. Due to the orthogonality of the different chaotic phase shifter, every pair of users can faithfully transmit quantum information through a common channel and have little crosstalk between different users. Meanwhile, the broadband spectra of chaotic signals efficiently help the quantum states to defend against channel loss and noise.

Special Property of Group Velocity for Temporal Dark Soliton**Supported by the National Nature Science Foundation of China under Grant No. 11404260, the Education Department of Shaanxi Province (16JK1758) and the State Key Laboratory of Quantum Optics and Optical Device (KF201602)

We investigate the speed of temporal dark soliton based on an optical coherent medium. It is demonstrated that the temporal dark soliton is described by a nonlinear Schrodinger equation whose coefficients are decided by the coherent medium. It is found that the speed of temporal dark soliton not only relies on the linear responses including GV parameter, group velocity dispersion parameter as well as the amplitude of dark soliton, but also relies on the nonlinear response like self-phase modulation parameter. Additionally, the dark soliton in anomalous-dispersion regime propagates slower than bright soliton, while in normal-dispersion regime it inversely propagates faster than bright soliton. The complicated property of the speed for dark soliton is quite different from the bright soliton whose speed is commonly only related to the group velocity parameter. We attribute this feature to the modulation instability of the nonlinear system.

Coupling Ideality of Integrated Planar High-QMicroresonators

Chipscale microresonators with integrated planar optical waveguides are useful building blocks for linear, nonlinear and quantum optical devices. Loss reduction through improving fabrication processes has resulted in several integrated micro resonator platforms attaining quality (Q) factors of several millions. However only few studies have investigated design-dependent losses, especially with regard to the resonator coupling section. Here we investigate design-dependent parasitic losses, described by the coupling ideality, of the commonly employed microresonator design consisting of a microring resonator waveguide side-coupled to a straight bus waveguide. By systematic characterization of multi-mode high-Q silicon nitride microresonator devices, we show that this design can suffer from low coupling ideality. By performing full 3D simulations to numerically investigate the resonator to bus waveguide coupling, we identify the coupling to higher-order bus waveguide modes as the dominant origin of parasitic losses which lead to the low coupling ideality. Using suitably designed bus waveguides, parasitic losses are mitigated, and a nearly unity ideality and strong overcoupling (i.e. a ratio of external coupling to internal resonator loss rate > 9) are demonstrated. Moreover we find that different resonator modes can exchange power through the coupler, which therefore constitutes a mechanism that induces modal coupling, a phenomenon known to distort resonator dispersion properties. Our results demonstrate the potential for significant performance improvements of integrated planar microresonators, achievable by optimized coupler designs.

Broadband sum-frequency generation using d33 in periodically poled LiNbO3 thin film in the telecommunications band.

We demonstrate the first, to the best of our knowledge, type-0 broadband sum-frequency generation (SFG) based on single-crystal periodically poled LiNbO3 (PPLN) thin film. The broad bandwidth property was largely tuned from mid-infrared region to the telecommunications band by engineering the thickness of PPLN from bulk crystal to nanoscale. It provides SFG a solution with both broadband and high efficiency by using the highest nonlinear coefficient d33 instead of d31 in type-I broadband SFG or second-harmonic generation. The measured 3 dB upconversion bandwidth is about 15.5 nm for a 4 cm long single crystal at 1530 nm wavelength. It can find applications in chip-scale spectroscopy, quantum information processing, LiNbO3-thin-film-based microresonator and optical nonreciprocity devices, etc.

Parity-time-symmetry enhanced optomechanically-induced-transparency.

We propose and analyze a scheme to enhance optomechanically-induced-transparency (OMIT) based on parity-time-symmetric optomechanical system. Our results predict that an OMIT window which does not exist originally can appear in weak optomechanical coupling and driving system via coupling an auxiliary active cavity with optical gain. This phenomenon is quite different from these reported in previous works in which the gain is considered just to damage OMIT phenomenon even leads to electromagnetically induced absorption or inverted-OMIT. Such enhanced OMIT effects are ascribed to the additional gain which can increase photon number in cavity without reducing effective decay. We also discuss the scheme feasibility by analyzing recent experiment parameters. Our work provide a promising platform for the coherent manipulation and slow light operation, which has potential applications for quantum information processing and quantum optical device.

Vortex quasi-crystals in mesoscopic superconducting samples**Project supported by the National Natural Science Foundation of China (Grant Nos. 11274009, 11434011, and 111522436), the National Key Basic Research Program of China (Grant No. 2013CB922000), the Research Funds of Renmin University of China (Grant Nos. 10XNL016 and 16XNLQ03), and the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices (Grant

There seems to be a one to one correspondence between the phases of atomic and molecular matter (AMOM) and vortex matter (VM) in superfluids and superconductors. Crystals, liquids, and glasses have been experimentally observed in both AMOM and VM. Here, we propose a vortex quasi-crystal state which can be stabilized due to boundary and surface energy effects for samples of special shapes and sizes. For finite sized pentagonal samples, it is proposed that a phase transition between a vortex crystal and a vortex quasi-crystal occurs as a function of magnetic field and temperature as the sample size is reduced.