This PDF file contains the front matter associated with SPIE Proceedings Volume 10029 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Narrow-band time-frequency entangled biphotons are generated from spontaneous four-wave mixing in cold atom clouds. The coherence time of the entangled biphotons can be extended to sub-microseconds by the slow light effect. The temporal wavefunction of the biphotons can be manipulated through modulating the spectral or spatial mode of the controlling laser beams. Concerning a pair of entangled biphoton and the resulting heralded single photon, it was commonly believed that, time-frequency entanglement damages the temporal purity of the single photon. However, the case is totally different for biphotons with long coherence time which is far beyond the time resolution of single-photondetectors. We demonstrate that, the single photon heralded from these time-frequency entangled biphotons is in a pure temporal state. Therefore, single photons are able to be shaped through the time-frequency entanglement with their partner photons, while the single photons could be found to be still in a pure state and thus useful for quantum information processing and communication technology.

Applying the mathematics of quantum information to a Poisson semiclassical photodetection model, we derive fundamental limits to parameter estimation and hypothesis testing with any measurement of weak incoherent optical sources via linear optics and photon counting. Connections with our recent work on superresolution imaging are highlighted.

The ultimate goal of quantum information science is to build a global quantum network, which enables quantum resources to be distributed and shared between remote parties. Such a quantum network can be realized using only fiber elements, thus deriving the advantages of low transmission loss, low cost, scalability, and integrability through mature fiber communication techniques such as dense wavelength division multiplexing. Hence high-quality entangled-photon sources based on fibers are in high demand. Here we report multiplexed polarization- and time-bin-entangled photon-pair sources based on the dispersion-shifted fiber operating at room temperature. The associated high quality of entanglement is characterized using interference, Bell’s inequality, and quantum state tomography. The simultaneous presence of both types of entanglement in multi-channel pairs of a 100-GHz dense wavelength division multiplexing device indicates a great capacity in distributing entangled photons over multiple users. Our design provides a versatile platform and takes a big step toward constructing an all-fiber quantum network.

In 1935, Einstein, Podolsky and Rosen published their influential paper proposing a now famous paradox (the EPR paradox) that threw doubt on the completeness of quantum mechanics. Two fundamental concepts: entanglement and steering, were given in the response to the EPR paper by Schrodinger, which both reflect the nonlocal nature of quantum mechanics. In 1964, John Bell obtained an experimentally testable inequality, in which its violation contradicts the prediction of local hidden variable models and agrees with that of quantum mechanics. Since then, great efforts have been made to experimentally investigate the nonlocal feature of quantum mechanics and many distinguished quantum properties were observed. In this work, along with the discussion of the development of quantum nonlocality, we would focus on our recent experimental efforts in investigating quantum correlations and their applications with optical systems, including the study of entanglement-assisted entropic uncertainty principle, Einstein-Podolsky-Rosen steering and the dynamics of quantum correlations.

Benefit from the recent nanotechnology process, people can integrate different nanostructures on a single chip. Particularly, quantum dots (QD), which behave as artificial atoms, have been shown to couple with a superconducting resonator, indicating that quantum-dot based quantum chip has a highly scalable possibility. Here we show a quantum chip architecture by combining graphene quantum dots and superconducting resonators together. A double quantum dot (DQD) and a microwave hybrid system can be described by the Jaynes-Cummings model, while a multi-quantum-dots system is conformed to the Tavis-Cummings model. These simple quantum optics models are experimentally realized in our device, providing a compelling platform for both graphene study and potential applications.

Long baseline optical interferometry, by combining the lights from widely-distributed telescopes, is shown to afford pronounced improvement in the imaging resolution in comparison with a single telescope. However, the noise and photon loss in the transmission between the telescopes would limit the length of baseline of interferometer to a few hundred meters. Here, we present a scheme for enhancement of long baseline optical interferometer by using quantum resources- noiseless linear amplifier (NLA) and displacement operation at the photon transmission channels. We exhibit this enhancement quantitatively by calculating higher fisher information compared with those of conventional optical interferometer.

Hybrid quantum state engineering in quantum communication and imaging^1-2 needs traceable quantum sensing and metrology, which are especially critical to quantum internet³ and precision measurements⁴ that are important across all fields of science and technology-. We aim to set up a mode of traceable quantum sensing and metrology. We developed a method by specially transforming an atomic force microscopy (AFM) and a scanning tunneling microscopy (STM) into a conducting atomic force microscopy (C-AFM) with a feedback control loop, wherein quantum entanglement enabling higher precision was relied upon a set-point, a visible light laser beam-controlled an interferometer with a surface standard at z axis, diffractometers with lateral standards at x-y axes, four-quadrant photodiode detectors, a scanner and its image software, a phase-locked pre-amplifier, a cantilever with a kHz Pt/Au conducting tip, a double barrier tunneling junction model, a STM circuit by frequency modulation and a quantum electrical triangle principle involving single electron tunneling effect, quantum Hall effect and Josephson effect⁵. The average and standard deviation result of repeated measurements on a 1 nm height local micro-region of nanomedicine crystal hybrid quantum state engineering surface and its differential pA level current and voltage (dI/dV) in time domains by using C-AFM was converted into an international system of units: Siemens (S), an indicated value 0.86×10^-12 S (n=6) of a relative standard uncertainty was superior over a relative standard uncertainty reference value 2.3×10^-10 S of 2012 CODADA quantized conductance⁶. It is concluded that traceable quantum sensing and metrology is emerging.

Entanglement generation between atomic ensembles is typically modeled using the framework of continuous variables (CV) which approximates discrete spin operators as canonical position and momentum operators. Although hugely successful with many applications, this approximation is valid only for small deviations in spin. Here we investigate entanglement generation between two atomic ensemble qubits using a measurement based scheme of a common light mode. Various methods of entanglement detection of the entangled state is discussed. We propose a entanglement witness for this state and discuss its further applications to optical states.

Nonlinear wavelength conversion provides flexible solutions for generating wideband tunable radiation in novel wavelength band. Parametric process in photonic crystal fibers (PCFs) has attracted comprehensive interests since it can act as broadband tunable light sources in non-conventional wavelength bands. The current state-of-the-art photonic crystal fibers can provide more freedom for customizing the dispersion and nonlinearity which is critical to the nonlinear process, such as four wave mixing (FWM), compared with the traditional fibers fabricated with doping techniques. Here we demonstrate broadband parametric wavelength conversion in our homemade photonic crystal fibers. The zero dispersion wavelength (ZDW) of PCFs is critical for the requirement of phase matching condition in the parametric four wave mixing process. Firstly a procedure of the theoretical design of PCF with the ZDW at 1060 nm is proposed through our homemade simulation software. A group of PCF samples with gradually variable parameters are fabricated according to the theoretical design. The broadband parametric gain around 1060 nm band is demonstrated pumped with our homemade mode locked fiber laser in the anomalous dispersion region. Also a narrow gain band with very large wavelength detune with the pump wavelength in the normal dispersion region is realized. Wavelength conversion with a span of 194 nm is realized. Furthermore a fiber optical parametric oscillator based on the fabricated PCF is built up. A wavelength tunable range as high as 340 nm is obtained. This report demonstrates a systematic procedure to realize wide band wavelength conversion based on PCFs.

We propose and experimentally demonstrate a generation scheme of telecom-band fiber-based frequency-degenerate polarization-entanglement photon pair source. Basing on the vector spontaneous four wave mixing process in a Sagnac fiber loop along the clockwise and counter-clockwise directions, two frequency-degenerate and polarization orthogonal biphoton states generate and then lead to the polarization entanglement states by the interference at the beamsplitter. The raw fringe visibilities of the two-photon interferences are 97% and 92%, respectively. Information can be encoded on the generated photon pairs using the polarization entangled Bell states. It is demonstrated by a simplified Bell state measurement with a fringe visibility of 83%.

Theoretically, we propose an investigation of the vectorial light field interacting with the isotropic Kerr medium. We obtain the analytical expression of the focal field of the hybrid polarized beam based on the vectorial Rayleigh-Sommerfeld formulas under the paraxial condition. Then we numerically simulate the far-field vectorial self-diffraction behavior and nonlinear ellipse rotation of a hybrid polarized beam by isotropic Kerr nonlinearity. Experimentally, we observe the vectorial self-diffraction behavior of the femtosecond-pulsed hybridly polarized beam in carbon disulfide at 800 nm, which is in agreement with the theoretical predictions. Our results demonstrate that the self-diffraction intensity pattern and the distribution of state of polarization (SoP) of a hybridly polarized beam could be manipulated by tuning the magnitude of the isotropic optical nonlinearity, which may find interesting applications in nonlinear mechanism analysis, nonlinear characterization technique, and spin angular momentum (SAM) manipulation.

We proposed and demonstrated pre-chirp managed amplification (PCMA), in which the seeding pulse was nonlinearly amplified such that the amplified spectrum was substantially broadened. By properly pre-chirping the seeding pulse, the amplified pulse can be compressed with the duration much shorter than the transform-limited duration allowed by the seeding spectrum. Using an Yb-doped rod-type large-pitch fiber as the power amplifier, PCMA has enabled us to generate 75 MHz, ~60 fs, linearly-polarized pulses with >100-W average power.

The enhanced nonlinear interaction in a silicon microcavity under coherent excitation is studied under different conditions. By controlling the pulse frequency drift, we guarantee, at every instant, the coincidence with the frequency resonance of the cavity that in the nonlinear regime suffers from a blue shift in time. This limiting shift effect is caused by the free carriers generated by the strong silicon two-photon absorption. Owing to the linear time-frequency relation of the pulse, the coupling efficiency to the drifted resonance can be maintained, further increasing the blue-shift. We study the input power effect after using different pulse durations.

We demonstrate nonlinear Fano effect in ultracold atom-molecule system composed of Photoassociation (PA) near a narrow d-wave Feshbach resonance for Cs atoms in the hyperfine state F = 3, mF = 3. A series of PA spectra of ultracold Cs atoms trapped in a crossed dipole trap are recorded near the Feshbach resonance. We measure PA rate as a function of magnetic field and clearly find Fano effect with characteristically asymmetric line shapes. Meanwhile, we investigate variations of spectral broadening and shifts as magnetic field around the Feshbach resonance. Our results also show Fano effect has a great effect on both spectral broadening and slope of spectral shift. We develop a nonlinear Fano theory based on magnato-optical quantum interferences in this ultracold atom-molecule system. The theory provides a remarkable agreement with our experimental results.

Lithium niobate on insulator platform, with excellent light confinement and second order nonlinearity, has recently attracted great interest for applications towards next-generation wavelength conversion systems that are highly efficient and can be densely fabricated. Here we propose and experimentally demonstrated efficient quasi-phase matched second harmonic generation in periodically-grooved lithium niobate waveguides with sub-micron dimensions. We show that, an additional momentum kick induced by periodically modulating the waveguide width could be used to compensate for the phase mismatch between the two fundamental modes at pump and second harmonic wavelengths. We measure normalized conversion efficiencies as high as 7.0% W^-1cm^-2 from the fabricated devices. This system is promising for future on-chip quantum wavelength conversion.

In this paper, the evolution of temporal soliton is investigated analytically when a laser pulse propagates in the inhomogeneous nonlinear medium with a Scarff II parity-time (PT)-symmetric potential. After a detailed analyzing the evolution of the intensity and pulse width (PW) of a temporal soliton, it is find that the chirped-free and chirped temporal soliton are stable when the dispersion coefficient is a periodic modulated function. When the dispersion coefficient are the constant and the exponential decreasing function, the chirped-free temporal soliton is stable, while the chirped temporal soliton is gradually compressed.

Quantum secure direct communication (QSDC) is an important branch of quantum cryptography. It can transmit secret information directly without establishing a key first, unlike quantum key distribution which requires this precursive event. One of the most highlighted QSDC protocol is the Two-step protocol. This paper will focus on proposing a frequency coding scheme in the Two-step protocol, while retaining other contents of the QSDC protocol. This new coding scheme will significantly increase the protocol’s ability against channel noise and loss, and provides an efficient protocol for secure direct quantum communication in a noisy environment. Besides, the frequency coding technology is also easy to understand and highly practical. After numerically simulating the performance of the protocol in a noisy channel, the results showed that the scheme was robust against channel noise and loss.

Practical quantum systems are open systems due to interactions with their environment. Understanding the evolution of open systems dynamics is important for quantum noise processes , designing quantum error correcting codes, and performing simulations of open quantum systems. Here we proposed an efficient quantum algorithm for simulating the evolution of an open quantum system on a duality quantum computer. In contrast to unitary evolution in a usual quantum computer, the evolution operator in a duality quantum computer is a linear combination of unitary operators. In this duality algorithm, the time evolution of open quantum system is realized by using Kraus operators which is naturally realized in duality quantum computing. Compared to the Lloyd's quantum algorithm [Science.273, 1073(1996)] , the dependence on the dimension of the open quantum system in our algorithm is decreased. Moreover, our algorithm uses a truncated Taylor series of the evolution operators, exponentially improving the performance on the precision compared with existing quantum simulation algorithms with unitary evolution operations.

We theoretically investigate a basic structure that the series-coupled double ring resonator coupled two straight waveguide. We calculate the transmission function and phase shift through transfer matrix theory .The system consists of two rings, three straight waveguide and four couplers which the drop port and the though port are coupled to a bus waveguide .We obtain a tunable flat delay line which mitigates the deleterious effects of group delay dispersion in this structure through adjusting 4 coupling coefficient of the couplers, the attenuation factor of ring waveguide and the perimeter of 2 rings. The ability to realize the phenomenon is important for applications such as optical switching, and tunable bandwidth filter applications.

We theoretically analyze the electromagnetically induced transparency (EIT)-like spectrum in the Eye-like resonator configuration. The EIT-like spectrum results from the interference between the inner ring and the outer ring. In this paper, we obtain a tunable group delay and bandwidth of the transparency window through changing the coupling coefficients and the attenuation factors of the inner and the outer ring. The tunable group delay and the bandwidth will have potential application in optical switching or tunable delay lines and tunable bandwidth filter.

In this work, two kinds of strip/slot hybrid As₂S₃ waveguides with the silicon dioxide slots, which are demonstrated to have low and flat dispersion profiles are proposed. Based on those waveguides, we obtain broadband and highly coherent supercontinuum numerically using the nonlinear Schrödinger equation. For the waveguide with a vertical silicon dioxide slot, the dispersion between ±20 ps/(nm∙km) from 1435 to 2800 nm is obtained by adjusting the structure parameters. The broadband spectrum covering from 1392 to 2916 nm at -35 dB level is generated in a 5.5-mm waveguide with high correlation of ~1. For the waveguide with a horizontal silicon dioxide slot, the dispersion spans ±4 ps/(nm∙km) from 1685 to 2770 nm and the generated spectrum with correlation of ~1 spans from 1212 to 3979 nm in a 5.5-mm waveguide.

We report here the detailed characteristics of 1.9 μm laser emission from hydrogen-filled hollow-core fiber by stimulated Raman scattering. A 6.5 m hydrogen-filled Ice-cream negative curvature hollow-core fiber is pumped with a high peak power, narrow linewidth, liner polarized subnanosecond pulsed 1064 nm microchip laser, generating pulsed 1908.5 nm vibrational Stokes wave. The linewidth of the pump laser and the vibrational Stokes wave is about 1 GHz and 2 GHz respectively. And the maximum Raman conversion quantum efficiency is about 48%. We also studied the pulse shapes of the pump laser and the vibrational Stokes wave. The polarization dependence of the vibrational and the rotational stimulated Raman scattering is also investigated. In addition, the beam profile of vibrational Stokes wave shows good quality, which may be taken advantage of in many applications.

Indium doped zinc oxide (IZO) thin films were grown on sapphire substrate by radio frequency (RF/DC) magnetron sputtering technique. The structural characterization and surface morphology of IZO thin films were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The XRD results show that the samples exhibit polycrystalline characteristics and still retained wurtzite structure. The surface morphology of the samples reveals the average crystallite sizes are increased as indium content. In addition, the linear optical properties of IZO thin films were studied by UV-VIS spectrometer with wavelength range 200-900 nm. The high transmittances and the band gap values were observed in both thin films. Moreover, the nonlinear optical absorption and refraction of IZO thin films were investigated using nanosecond Z-scan technique. These samples show self-focusing optical nonlinearity and good two-photon nonlinear optical absorption behaviors. Therefore, these studies make the IZO thin films as the applications in nonlinear optical devices.

Search on improved-glued-binary-trees is a representative example of quantum superiority, where exponential acceleration can be achieved using quantum walk with respect to any classical algorithms. Here we analyzed the evolution process of this quantum-walk-based algorithm. Several remarkable features of the process are revealed. Generation of the model by introducing tunable defect strength and double defects is also discussed and the effects of these generalization on evolution process, arrival probability and residual probability are discussed in details. Physical implementation with silicon ridge waveguide array is presented. The design of the array with FEM method are presented and light propagation simulation with FDTD method shows that this kind of structure is feasible for the task. Lastly, preliminary experimental demonstration with classical coherent light simulation are presented. Our results show that silicon photonic chips are suitable for such search problems and opening a route towards large-scale photonic quantum computation.

We experimentally generated the duration-controllable square-wave pulse from an L band dissipative soliton (DS) fiber laser based on the dispersive Fourier transformation (DFT) technique. The rectangular spectrum emitted from an L band dissipative soliton fiber laser is mapped into a time-domain coherent rectangular waveform through the DFT technique. The duration of the square-wave pulse can be controllable with the adjustments of the pump power. The results demonstrate that it is an effective and flexible way to achieve duration-controllable square-wave pulses by combinating with DFT technique and DS fiber laser.

By considering propagation equations of Stokes-waves for different orders of the stimulated Brillouin scattering (SBS) and the stimulated Raman scattering (SRS) together with propagation-rate equations of Ytterbium-doped double-clad fiber amplifiers, we numerically analyze steady-state characteristics of these amplifiers such as Amplified Spontaneous Emission (ASE) and threshold pump power and parameters which have influence over it such as pumping configuration, pumping wavelength, input signal wavelength, input signal power, input signal bandwidth and amplifier geometry. Also in an experimental setup threshold pump powers under both forward and backward pumping configurations are measured. Our results are of prime importance for applications such as nonlinear frequency generation.

In this paper, the supercontinuum (SC) generation in a carbon disulfide (CS₂)-filled photonic crystal fiber (PCF) with strong slow nonlinearity is investigated. When the PCF is pumped at 1.55 μm in the anomalous dispersion region, we obtain highly coherent SC spanning from 0.99 to 2.32 μm, at -40 dB level. Moreover, the influences of the slow nonlinearity, the input pulse width, the pulse peak power, the fiber length, and the temperature on the supercontinuum generation (SCG) are studied. The role of the slow nonlinearity in enhancing the coherence of SC is proved. To our best knowledge, this is the first demonstration on generating the octave-spanning SC with high coherence using the slow nonlinearity of CS₂. CS₂ is a material that has high nonlinearity coefficient and well transparency in infrared. What’s more, the slow nonlinearity is very strong in this material.

Propagation of strong femtosecond hyper-Gaussian pulses in an organic molecular medium is studied by solving numerically the Maxwell-Bloch equations using an iterative predictor-corrector finite-difference time-domain technique. The carrier-wave frequency of the field is tuned in two-photon resonance with the molecular system simplified by a cascade three-level model. Strong two-photon absorption induced optical power limiting behavior is observed for the hyper-Gaussian pulses of different orders. For the ultrashort hyper-Gaussian pulses, it is found that the ”two-photon area” is no further the deciding quantity of the two-photon induced dynamics, and pulses with different temporal profiles will induce different two-photon absorption dynamics and optical limiting processes. With the same pulse duration and field amplitude, pulses of a lower order is found to have a larger input ”two-photon area” but a smaller output area, and therefore show a better optical limiting behavior. The population distribution and the generation of new fields during pulse propagation also depend on the shape of the incident field.

Electromagnetically induced transparency (EIT) is a significant nonlinear optical phenomenon. Based on the theory of density matrix equation, we presented the influence of Doppler effect on EIT. A cascade type three-level system and Na atomic vapor is adopted during the course. The results showed that EIT is determined by Rabi frequency of the couple and probing field. It is independent of temperature usually. But when we take Doppler effect into account, it is found that the full transparency appeared at the condition of Ω_P=0.01GHz, Ω_C=1GHz will vary with temperature. An obvious transparent window can be observed only when the temperature is less than 50K. With the increase of temperature, EIT phenomenon disappeared quickly. At room temperature, we can see that the double peaks of Aulter-Townes will instead of the EIT transparent window as Rabi frequency of the couple field is larger than 1.5GHz.

Among the demerits of standard nonlinear amplifying loop mirrors (NALM), one can single out the dependence of its reflectivity upon the intensity of the intra-cavity. This results in a relatively narrow range of radiation power, within which stable mode-locked operation of a fibre laser with NALM can be achieved. This work reports for the first time that in the process of generation, the NALM reflectivity may be controlled independently of the intra-cavity radiation power by using two different active media with independent pump sources. The newly proposed layout allows stable mode locking within a substantially broader radiation power range and enables achievement of record-high pulse parameters.

This work reports on possibilities of contrast enhancement of dynamically excited coherent population trapping (CPT) resonance in ⁸⁷Rb vapour arising from application of feedback methods. Controlling the bichromatic pump radiation power through a feedback loop that stabilises Rb atom luminescence when scanning the frequency difference of the bichromatic pump radiation resulted in a more than an order-or-magnitude improvement in the amplitude of the CPT resonance at scanning frequencies over 100 Hz. It is established that the excursion of the pump radiation power controlled by the feedback loop under dynamic excitation is by an order of magnitude smaller than that under quasistationary excitation at scan frequencies < 1 Hz.

Motivated by the robust immunity to interference as well as the higher spectrum efficiency, Orthogonal Frequency Division Multiplexing (OFDM) has been widely considered as one of the strongest contenders for high-speed Next- Generation Passive Optical Networks (NG-PONs), which satisfies the huge surge in demand for high-speed broadband services. In the other hand, OFDM systems suffer from a high Peak-to-Average Power Ratio (PAPR) at the transmitted signal resulting in signal degradation. The simplest method to deal with the PAPR problem consists in applying deliberate clipping to the transmitted signal which significantly reduces the requirement of the received optical power. In this paper, an analytical evaluation for the performance of an IM/DD optical OFDM system is shown, this is while accounting for clipping distortion and quantification noise caused by the limited bit resolution of DAC converter. Moreover, the paper demonstrates that applying digital signal restoration at the system receiver enables further improvements in the system performances in terms of enhanced effective Signal-to-Noise Ratio (SNR) and reduced optical power that is required to achieve specified Bit-Error-Rate (BER).