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Accepted papers to appear in an upcoming issue

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Transfer of temporal coherence in parametric down-conversion

Anand Jha, Girish Kulkarni, and Prashant Kumar

Doc ID: 295911 Received 17 May 2017; Accepted 22 Jun 2017; Posted 22 Jun 2017  View: PDF

Abstract: We show that in parametric down-conversion the coherence properties of a temporally partially coherent pump field get entirely transferred to the down-converted entangled two-photon field. Under the assumption that the frequency-bandwidth of the down-converted signal-idler photons is much larger than that of the pump, we derive the temporal coherence functions for the down-converted field, for both infinitely fast and time-averaged detection schemes. We show that in each scheme the coherence function factorizes into two separate coherence functions with one of them carrying the entire statistical information of the pump field. In situations in which the pump is a Gaussian Schell-model field, we derive explicit expressions for the coherence functions. Finally, we show that the concurrence of time-energy-entangled two-qubit states is bounded by the degree of temporal coherence of the pump field. This study can have important implications for understanding how correlations of the pump field manifest as two-particle entanglement as well as for harnessing energy-time entanglement for long-distance quantum communication protocols.

Simultaneously high-Q and high-sensitivity slotted photonic crystal nanofiber cavity for complex refractive index sensing

Chao-Sheng Deng, Jian-Xin Zhong, Jie Peng, Wen-Liang Liu, and Ming-Jun Li

Doc ID: 287020 Received 17 Feb 2017; Accepted 21 Jun 2017; Posted 22 Jun 2017  View: PDF

Abstract: We proposed and theoretically investigated a novel one-dimensional slotted photonic crystal nanofiber cavity (SPCNC) for complex refractive index sensing in gaseous environment. Three-dimensional finite-difference time-domain simulations show that a high quality factor (Q) of 1.45*10^6 and a high sensitivity of 756 nm/RIU (refractive index unit) can be simultaneously achieved for the detection of the real part of the refractive index (RI) of the surrounding gas. In addition, we demonstrated the SPCNC possesses the capability of detecting the change of the imaginary part of the RI. A high sensitivity of 1525 nm/RIU is obtained and Q is found to decrease with increasing absorption strength but still remains as high as 1.1*10^4 for strong absorption. We believe our proposed SPCNC with excellent sensing performances, ultrasmall mode volume and compact footprint may offer the potential to develop multiplexed sensing techniques for applications in multi-element mixture detection.

Optical Barium Ion Qubit

Dahyun Yum, Debashis De Munshi, Tarun Dutta, and Manas Mukherjee

Doc ID: 290145 Received 14 Mar 2017; Accepted 21 Jun 2017; Posted 22 Jun 2017  View: PDF

Abstract: We demonstrate an optical single qubit based on a narrow 6S1/2 to 5D5/2 quadrupole transition of a single Ba+ ion operated by only diode based lasers. The characteristic properties of the qubit are discussed based on the Divicezo's criteria. We observe continuous bit-flip oscillations at a rate of about 250 kHz which is fast enough for a qubit operation as compared to the measured coherence time of over 3~ms. We also present a technique to quantify the bit-flip error in each qubit NOT gate operation.

{Squeezed Thermal States: The Result of Parametric Down Conversion in Lossy Cavities

Hossein Seifoory, Sean Doutre, Marc Dignam, and John Sipe

Doc ID: 293195 Received 25 Apr 2017; Accepted 16 Jun 2017; Posted 16 Jun 2017  View: PDF

Abstract: We investigate theoretically the properties and the temporal evolution of squeezed states generated using degenerate parametric down conversion in lossy cavities. We show that the Lindblad master equation, which governs the evolution of this system, has as its solution a squeezed thermal state with an effective temperature and squeezing parameter that depends on time. We derive analytical solutions for the time-evolution of quadrature noise, thermal photon number, squeezing parameter, and total photon number under different pumping regimes. We also find the steady state limits of the quadrature noises and discuss the $ g^{(2)} $ factor of the generated light inside the cavity in the steady state.

Wigner function and entanglement dynamics of Two-atom two-mode nonlinear Jaynes-Cummings model

Hassan Safari, Mahnaz Ghorbani, and Mohammad Javad Faghihi

Doc ID: 290336 Received 08 Mar 2017; Accepted 15 Jun 2017; Posted 16 Jun 2017  View: PDF

Abstract: In this paper, a model in which two moving atoms interact with a two-mode field with nondegenerate two-photon transitions is studied in the presence of intensity-dependent coupling. To discuss the entanglement dynamics between subsystems as well as nonclassicality of the system, the time-dependent form of the state vector of the system is exactly obtained. The dynamics of entanglement between the atoms and the field is evaluated by the von Neumann entropy. To examine the degree of entanglement between the atoms, concurrence and negativity are obtained. Then, in order to understand the nonclassicality feature of the state vector of the system, the two-mode Wigner-Weyl quasi-probability distribution function is precisely derived. It is deduced from the numerical results that the domain and the maximum amount of the degree of entanglement and nonclassicality of the system can be appropriately tuned by suitably adopting the nonlinearity function and the field-mode structure parameters.

Theoretical study of laser–mode competition in quantum–dot semiconductor lasers using a self–consistent electro–opto–thermal model

hossein yousefvand and Ziba Faris

Doc ID: 292613 Received 10 Apr 2017; Accepted 13 Jun 2017; Posted 14 Jun 2017  View: PDF

Abstract: We present a new model for quantum–dot (QD) semiconductor lasers which includes the self–consistent treatment of electrical, optical and thermal interactions. The approach is developed from the energy balance equation to incorporate the carrier temperature and a three–level rate equations to describe the carrier and photon dynamics within the QD active region operating simultaneously on two longitudinal modes; via ground–state (GS) and the first excited–state (ES) transitions. Using the presented model, the steady–state, small–signal modulation response and transient device characteristics are calculated and analyzed. Similar to the situation of mode competition of laser modes, it is found that the light output power of GS mode enters the roll–off regime, while the power of ES mode increases. The model also predicts the negative temperature dependency of the power threshold for the ES mode, which can be understood from the negative temperature–dependent behavior of incomplete clamping of the ES population above the GS threshold. The simulated results are in good agreement with experimental data from the devices reported earlier.

Broadband LWIR and MWIR Metamaterial Absorbers with a Simple Design Topology: Almost Perfect Absorption and Super-Octave Band operation in MWIR Band

Kadir Ustün and GONUL TURHAN-SAYAN

Doc ID: 285906 Received 31 Jan 2017; Accepted 12 Jun 2017; Posted 14 Jun 2017  View: PDF

Abstract: Wideband infrared absorbers are not only important in the design of various sensors and thermal emitters but they are also crucial in the design of IR imagers for defense applications. In this study, we propose simple structures of wideband metamaterial absorbers operating in long-wave infrared and mid-wave infrared wavelengths of the electromagnetic spectrum. Our wideband absorbers have the ability to fill the wavelength intervals, 8 µm to 12-13 µm or 3 µm to 5 µm, where the atmosphere shows transparent behavior. The suggested metamaterial absorbers are mostly thin structures consisting of three functional layers; patterned metal layer - planar dielectric layer - ground metal layer, from top to bottom. The metal pattern is four-fold symmetric to satisfy polarization insensitive operation under normal incidence. The metamaterial patterns are chosen in extremely simple forms to facilitate the lithography process. We intentionally use a low-conductivity metal such as titanium at the top layer of the absorber to increase the overall operational bandwidth of absorption. Extraordinary results such as almost perfect absorption and super-octave band operation are demonstrated especially in the MWIR region. Oxidation of the lossy metal layer may lend itself as an important practical problem. Effects of applying a very thin protective coating layer on top of the titanium metasurface are also investigated in the article.

Artificial electrostriction in composite materials

Ashwin Singh, Michael Smith, and C. Martijn de Sterke

Doc ID: 291865 Received 31 Mar 2017; Accepted 08 Jun 2017; Posted 14 Jun 2017  View: PDF

Abstract: We examine the role of artificial electrostriction in composites comprising solid materials, extending earlier theoretical models that omit the effect of shear. We accurately describe artificial electrostriction in such materials and present results for a selection of technologically important material combinations.

A simplified proposal for realizing multiqubit tunable phase gate in circuit QED

Wen-An Li and Yuan Chen

Doc ID: 292211 Received 06 Apr 2017; Accepted 08 Jun 2017; Posted 14 Jun 2017  View: PDF

Abstract: We propose a scheme to realize multiqubit tunable phase gate in a circuit QED setup where two resonators each coupling with a qudit are interconnected to a common qudit (d = 4). In this proposal, only two levels of each qudit serve as the logical states and other two levels are used for the gate realization. The proposal is efficient and simple because only a classical microwave pulse is needed, no matter how many qudits are involved, which significantly reduces experimental difficulty. In non-resonant case, the tunable phase gate can be achieved readily, while under the resonant condition a π-phase gate can be realized after a full cycle of Rabi oscillation where the gate speed is rather fast due to the resonant interaction. We have shown that the resulting effective dynamics allows for the creation of high fidelity phase gate. The influence of various decoherence processes such as the decay of the resonator mode, and the relaxation of the qudits is investigated. Moreover, the proposed scheme can be easily generalized to realize N-qubit phase gate.

Dark mode metasurfaces: sensing optical phase difference with subradiant modes and Fano resonances

Ann Roberts, Tim Davis, and Daniel Gomez

Doc ID: 285936 Received 31 Jan 2017; Accepted 07 Jun 2017; Posted 14 Jun 2017  View: PDF

Abstract: We computationally investigate the excitation of subradiant modes and Fano resonances of arrays of simple antenna elements with subwavelength dimensions. We show that periodic arrangements of dipoles on a flat surface provide a highly flexible approach for developing a range of metasurfaces with high sensitivity to both the wavelength of the incident radiation and angle of incidence.

Entanglement-enhanced Neyman-Pearson target detection using quantum illumination

Jeffrey Shapiro, Quntao Zhuang, and Zheshen Zhang

Doc ID: 291263 Received 23 Mar 2017; Accepted 07 Jun 2017; Posted 14 Jun 2017  View: PDF

Abstract: Quantum illumination (QI) provides entanglement-based target detection — in an entanglement-breaking environment — whose performance is significantly better than that of optimum classical-illumination target detection. QI's performance advantage was established in a Bayesian setting with the target presumed equally likely to be absent or present and error probability employed as the performance metric. Radar theory, however, eschews that Bayesian approach, preferring the Neyman-Pearson performance criterion to avoid the difficulties of accurately assigning prior probabilities to target absence and presence and appropriate costs to false-alarm and miss errors. We have recently reported an architecture---based on sum-frequency generation (SFG) and feedforward (FF) processing---for minimum error-probability QI target detection with arbitrary prior probabilities for target absence and presence. In this paper, we use our results for FF-SFG reception to determine the receiver operating characteristic — detection probability versus false-alarm probability — for optimum QI target detection under the Neyman-Pearson criterion.

A transmission-bias metaheuristic for design optimization of optical structures

Sacha Verweij and Shanhui Fan

Doc ID: 290297 Received 10 Mar 2017; Accepted 18 May 2017; Posted 19 May 2017  View: PDF

Abstract: Search algorithms play a crucial role in systematic design optimization of optical structures. Though many sophisticated methods appear in the literature, physically motivated guiding principles for the design and enhancement of such methods are few. We introduce such a guiding principle --- a transmission- bias metaheuristic --- and demonstrate its value in practice. Specifically, we present a case study in which application of this metaheuristic leads to significantly better performing variants of a simple stochastic local search algorithm --- restarted iterative best improvement --- on a challenging design optimization problem --- combinatorial design optimization of a multi-spatial-mode photonic crystal waveguide bend that preserves modal content.

Analytical qualitative modelling of passive and active metamaterials

Arkadi Chipouline and Franko Küppers

Doc ID: 290288 Received 07 Mar 2017; Accepted 05 May 2017; Posted 31 May 2017  View: PDF

Abstract: The era of metamaterials (MM) was ushered in with the publication of the widely known paper by Prof. V. Veselago who first suggested that the basic principles of electrodynamics do not forbid the possibility of materials with negative values of the real parts of both the permittivity and permeability. MMs are artificial media which tailor the macroscopic properties of light propagation by a careful choice of a microscopic unit cell (called the metaatom - MA) from which they are constructed. MM design in the optical domain is mainly carried out using rigorous Maxwell’s equation solvers like finite difference time-domain simulations, finite-element methods, and Fourier modal methods. In contrast to such numerical techniques, the analytical description of MMs is much less developed. There is the evident inclination in favor of numerical methods in order to describe the optical properties of MMs at the expense of physical intuition. There is no doubt that modern numerical algorithms and available computer facilities provide the main way to investigate more or less complicated problems. Nevertheless, the qualitative approximate type models can provide a deeper understanding of the basic physical processes, stimulate discussion of new effects, and even provide new paradigm for optimization of a particular design. The qualitative models are complimentary to the numerical ones, taking advantages of careful comparison with the results of rigorous numerical calculations, but at the same time remaining analytically treatable. Elaboration of the qualitative models in the frame of the same paradigm appears to be useful not only at the consideration of the specific problems, but at the teaching of the respective courses as well. The qualitative models allow us to show mutual self-consistency of the physical theory (in this particular case in application to the MM), which otherwise could be seen as a huge leap from independent experimental to theoretical facts. In this review, the macroscopic approach to the homogenization has been outlined resulting in three possible representations of ME – Casimir “C”, Landau&Lifshitz “L&L”, and new Toroidal “T” forms. The Serdyukov-Fedorov transformations (SFT) have been reformulated and used to establish relationships between the three representations of ME. A new form of material equations has been suggested in the frame of the phenomenological approach in the case of weak (up to the second order) dispersion. The multipole approach to the homogenization of the MM has been formulated in case of classical charge dynamics of the MAs, and the dispersion relation has been elaborated. The analytical treatment has been extended to the case of MM with the significant coupling between neighboring MA in the lateral direction. In extending the multipole approach to the case of random MMs, the effect of spatial distribution of the MAs was taken into account by considering the near field coupling between neighboring MAs. It has been shown that the specific convective carrier oscillations together with the quadrupole moment inherently introduce nonlinear material interactions. A magnetic resonance contribution to third-order optical nonlinearities of the fishnet MM was shown. The multipole approach has been extended on the case of the quantum MM, where quantum physics appeared to be necessary for adequate modelling of the dynamics of MAs. An application of the developed model for enhancement of saturation nonlinearity in the system of coupled carbon nano tubes (CNT) and MM has been demonstrated. The coupled dynamics model of the plasmonic nanoresonator and quantum emitter has been applied to describe regular and stochastic properties of the nanolaser (spaser). The problem of monochromatic plane wave propagation in the MM consisting of quantum MAs has been considered.

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