Search

Breaking the symmetry between forward- and backward-propagating optical modes is of fundamental scientific interest and enables crucial functionalities, such as isolators, circulators, and duplex communication systems. Although there has been progress in achieving optical isolation on-chip, integrated broadband nonreciprocal signal processing functionalities that enable transmitting and receiving via the same low-loss planar waveguide, without altering the frequency or mode of the signal, remain elusive. Here, we demonstrate a nonreciprocal delay scheme based on the unidirectional transfer of optical data pulses to acoustic waves in a chip-based integration platform. We experimentally demonstrate that this scheme is not impacted by simultaneously counterpropagating optical signals. Furthermore, we achieve a bandwidth more than an order of magnitude broader than the intrinsic optoacoustic linewidth, linear operation for a wide range of signal powers, and importantly, show that this scheme is wavelength preserving and avoids complicated multimode structures.

In this article we report on the experimental investigation of light storage for several types of diffraction-free beams (Bessel and Airy beams) and quasi-diffraction-free beams by utilizing electromagnetically induced transparency (EIT) technique in a hot atomic gas cell. The experimental results show that the diffraction-free and quasi-diffraction-free beams have better storage performances when compared with ordinary images possessing similar spatial profiles. Meanwhile, the Bessel beams and the quasi-diffraction-free images are able to maintain their spatial profiles with a long storage time while the side-lobes of the Airy beam are gradually depleted with the increment of the storage time. We quantitatively analyze the storage results and give physical explanations behind these phenomena. Furthermore, the self-healing of the retrieved diffraction-free beams is verified, signifying that their characteristics preserve well after storage.

We theoretically investigate the super- and sub-radiance from the resonant dipole-dipole interactions (RDDI) in a confined two-dimensional (2D) reservoir. The distinctive feature of 2D RDDI shows qualitatively and quantitatively different long-range behavior from RDDI in free space. We investigate the superradiant properties of the singly-excited symmetric state under this 2D RDDI. This state also allows subradiant decays in much longer distances than the transition wavelength, showing long-range atom-atom correlations. We further study the dynamics of the subradiant states which can be accessed by imprinting spatially dependent phases on the atomic arrays. Our results demonstrate rich opportunities in engineering light-matter interactions in a confined 2D reservoir, and hold promise in applications of quantum light storage and single-excitation state manipulations., Comment: 4 figures

We present an improved version of the superatom (SA) model to examine the slow-light dynamics of a few-photons signal field in cold Rydberg atoms with van der Waals (vdW) interactions. A main feature of this version is that it promises consistent estimations on total Rydberg excitations based on dynamic equations of SAs or atoms. We consider two specific cases in which the incident signal field contains more photons with a smaller detuning or less photons with a larger detuning so as to realize the single-photon-level light storage. It is found that vdW interactions play a significant role even for the slow-light dynamics of a single-photon signal field as distributed Rydberg excitations are inevitable in the picture of dark-state polariton. Moreover, the stored (retrieved) signal field exhibits a clearly asymmetric (more symmetric) profile because its leading and trailing edges undergo different (identical) traveling journeys, and higher storage/retrieval efficiencies with well preserved profiles apply only to weaker and well detuned signal fields. These findings are crucial to understand the nontrivial interplay of single-photon-level light storage and distributed Rydberg excitations.[Figure not available: see fulltext.].

We provide an entropy analysis for light storage and light retrieval. In this analysis, entropy extraction and reduction in a typical light storage experiment are identified. The spatiotemporal behavior of entropy is presented for D1 transition in cold sodium atoms. The governing equations are the reduced Maxwell field equations and the Liouville–von Neumann equation for the density matrix of the dressed atom.

The application of electrolyzed water effectively reduces microbial contamination and has greatly contributed to delayed meat spoilage. However, concerns about applying electrolyzed water in the meat industry, which include the stability of available chlorine in various storage conditions, corrosion resistance and residual chlorate, have attracted much attention. In this study, primary concerns regarding acid electrolyzed water (AEW) and slightly acid electrolyzed water (sAEW) were evaluated in comparison to those of sodium hypochlorite (SH) widely used in meat processing plants. The results showed that closed and 4 °C storage conditions, which just declined about 30% ACC of available chlorine concentration (ACC), were more beneficial than open and 20 °C storage conditions for maintaining the stability of electrolyzed water, whereas no differences in stability were observed between dark and light storage. The decline of ACC positively depended on the concentrations of organic materials ranged from 0.1% to 0.3%, and the ACC was close to 10 mg/mL after 30 min trearment. The corrosion of AEW was equal to that of SH, but it was higher than that of sAEW. In addition, the concentration of residual chlorate in meat sprayed by electrolyzed water was less than meat sprayed by SH. The findings suggested that electrolyzed water is a great potential substitute for SH in the meat industry.

Light storage in an optical fiber is an attractive component in quantum optical delay line technologies. Although silica-core optical fibers are excellent in transmitting broadband optical signals, it is challenging to tailor their dispersive property to slow down a light pulse or store it in the silica-core for a long delay time. Coupling a dispersive and coherent medium with an optical fiber is promising in supporting long optical delay. Here, we load cold Rb atomic vapor into an optical trap inside a hollow-core photonic crystal fiber, and store the phase of the light in a long-lived spin-wave formed by atoms and retrieve it after a fully controllable delay time using electromagnetically-induced-transparency (EIT). We achieve over 50 ms of storage time and the result is equivalent to 8.7x10^-5 dB s^-1 of propagation loss in an optical fiber. Our demonstration could be used for buffering and regulating classical and quantum information flow between remote networks.

We design a compact photonic crystal system to effectively trap, store and release a signal pulse on demand, based on controllable EIT-like effect in dynamically tuned cascaded nanocavities.

We prove that optimal control of light energy storage in disordered media can be reached by wavefront shaping. For this purpose, we build an operator for dwell-times from the scattering matrix, and characterize its full eigenvalue distribution both numerically and analytically in the diffusive regime, where the thickness $L$ of the medium is much larger than the mean free path $\ell$. We show that the distribution has a finite support with a maximal dwell-time larger than the most likely value by a factor $(L/\ell)^2\gg 1 $. This reveals that the highest dwell-time eigenstates deposit more energy than the open channels of the medium. Finally, we show that the dwell-time operator can be used to store energy in resonant targets buried in complex media., 6 pages, 3 figures, + SI

Broadband spin-photon interfaces for long-lived storage of photonic quantum states are key elements for quantum information technologies. Yet, reliable operation of such memories in the quantum regime is challenging due to photonic noise arising from technical and/or fundamental limitations in the storage-and-recall processes controlled by strong electromagnetic fields. Here, we experimentally implement a single-photon-level spin-wave memory in a laser-cooled Rubidium gas, based on the recently proposed Autler-Townes splitting (ATS) protocol. We demonstrate storage of 20-ns-long laser pulses, each containing an average of 0.1 photons, for 200 ns with an efficiency of $12.5\%$ and signal-to-noise ratio above 30. Notably, the robustness of ATS spin-wave memory against motional dephasing allows for an all-spatial filtering of the control-field noise, yielding an ultra-low unconditional noise probability of $3.3\times10^{-4}$, without the complexity of spectral filtering. These results highlight that broadband ATS memory in ultracold atoms is a preeminent option for storing quantum light., 6 pages, 4 figures

Small crafts play an important role in marine development, and the development of power propulsion technology determines the operational performance of the aircraft. Aiming at the special requirements of small aircraft function, structure and operating environment, based on the analysis of the operation characteristics and influencing factors of small aircraft, the general design flow of power propulsion system construction is proposed, and the marine clearing navigation is carried out with a certain design. As an example, the design verification of the power propulsion system is carried out, and the relevant conclusions can provide a reference for the construction of the small aircraft propulsion system.

C-phycocyanin is a bright blue natural colorant used in food and beverage applications. However, its color stability is poor in acidic conditions under exposure to light. In this work, we study the use of whey protein isolate (WPI) to protect C-phycocyanin from color degradation. Low concentration (0.05-0.1%) WPI addition delayed (~2 days) the color degradation of C-phycocyanin at pH 3.0 over 5-day storage in light. However, the color degradation was aggravated adversely during 5-day light storage when C-phycocyanin mixed with a higher concentration (~1%) of WPI degraded after heat-treatment. The Fourier transform infrared and fluorescence spectroscopy confirmed that structural changes (e.g., alpha-helix protection and transformation from alpha-helix to beta-sheet) of C-phycocyanin due to interaction with WPI. These results, along with quartz crystal microbalance with dissipation technology outcomes, suggest that a low concentration of WPI may help protect C-phycocyanin's secondary structure from becoming damaged during light storage, preventing its color degradation.

Potatoes (Solanum tuberosum L) are included in priority crops considering their function as a source of carbohydrates in food diversification. One of the techniques in producing quality seed is through tissue culture continued within in vitro tuber production that is micro tubers. The aim of this research was to observe the effect of GA3 concentration, storage, and size of micro tubers on breaking dormancy. The activities were carried out in the tissue culture laboratory of IVEGRI from April to July 2018. The treatments were to determine the effect of GA3 (10,15,20 ppm) and the size of micro tubers cv. Granola i.e. large (>4 g); small (1 g - 3 concentration does not affect the percentage shoot growth which initializes the breaking dormancy of tubers at 8 to 10 WAS (Weeks After Storage). Average shoot number 0.3 – 1.25 per tuber and shoot length 0.30 – 0.80 cm. In general, each micro tuber only grows one shoot. On visual observation, the large size of micro tubers will have quality and length of shoot better than small size micro tubers.

We investigate the rephasing efficiency of sequences of phased pulses for spin echoes and light storage by electromagnetically induced transparency (EIT). We derive a simple theoretical model and show that the rephasing efficiency is very sensitive to the phases of the imperfect rephasing pulses. The obtained efficiency differs substantially for spin echoes and EIT light storage, which is due to the spatially retarded coherence phases after EIT light storage. Similar behavior is also expected for other light-storage protocols with spatial retardation or for rephasing of collective quantum states with an unknown or undefined phase, e.g., as relevant in single-photon storage. We confirm the predictions of our theoretical model by experiments in a ${\mathrm{Pr}}^{3+}$:${\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ crystal.

We provide an entropy analysis for light storage and light retrieval. In this analysis, entropy extraction and reduction in a typical light storage experiment are identified. The spatiotemporal behavior of entropy is presented for D1 transition in cold sodium atoms. The governing equations are the reduced Maxwell field equations and the Liouville–von Neumann equation for the density matrix of the dressed atom.

In an optomechanical resonator, the optical and mechanical excitations can be coherently converted, which induces a transparency window for a weak probe laser beam. Here, we report an experimental study of transient optomechanically induced transparency (OMIT) using the silica microsphere with the breathing modes. The transient OMIT behavior obtained are in good agreement with theoretical calculations. In addition, the coherent interconversion between optical and mechanical excitations that can be used for light storage and readout has also been studied here. Our experimental results indicate that the light storage is closely related to the process of OMIT, and the photon-phonon conversion can be further applied to optical wavelength or optical mode conversion.

International audience; We review a series of quantum memory protocols designed to store the quantum information carried by light into atomic ensembles. In particular, we show how a simple semiclassical formalism allows to gain insight into various memory protocols and to highlight strong analogies between them. These analogies naturally lead to a classification of light storage protocols into two categories, namely photon echo and slow-light memories. We focus on the storage and retrieval dynamics as a key step to map the optical information into the atomic excitation. We finally review various criteria adapted for both continuous variables and photon-counting measurement techniques to certify the quantum nature of these memory protocols.

Storing and delaying optical signals plays a crucial role in data centers, phased array antennas, communication and future computing architectures. Here, we show a delay scheme based on cascaded Brillouin light storage, that achieves multi-stage delay at arbitrary positions within a photonic integrated circuit. Importantly these multiple resonant transfers between the optical and acoustic domain are controlled solely via external optical control pulses, allowing cascading of the delay without the need of aligning multiple structural resonances along the optical circuit., Comment: 5 pages, 5 figures, Birgit Stiller and Moritz Merklein contributed equally to this work

We investigate in theory the ultraslow light propagation and reversible light storage in a Pr 3+ : Y 2 SiO 5 crystal driven into the electromagnetically induced transparency regime. By carefully adjusting several critical parameters, we can well recover relevant experimental results in terms of the time delay, the energy loss, the pulse width, and the retrieval efficiency of the transmitted signal. Our results depend on full numerical solutions of the coupled Maxwell–Liouville equations with the inhomogeneous broadenings properly dealt with.

We propose an effective method to achieve extremely slow light by using both the mechanism of electromagnetically induced transparency (EIT) and the localization of a coupled cavity waveguide (CCW). Based on quantum mechanics theory and the dispersion relation of a CCW, we derive a group-velocity formula that reveals both the effects of the EIT and CCW. Results show that ultralow light velocity at the order of several meters per second or even static light, could be obtained feasibly. In comparison with the EIT mechanism in a background of vacuum, this proposed method is more effective and realistic to achieve extremely slow light. And it exhibits potential values in the field of light storage.

151 E u 3 + -doped yttrium silicate ( 151 E u 3 + : Y 2 S i O 5 ) crystal is a unique material that possesses hyperfine states with coherence time up to 6 h. Many efforts have been devoted to the development of this material as optical quantum memories based on bulk crystals, but integrable structures (such as optical waveguides) that can promote 151 E u 3 + : Y 2 S i O 5 -based quantum memories to practical applications have not been demonstrated so far. Here we report the fabrication of type II waveguides in a 151 E u 3 + : Y 2 S i O 5 crystal using femtosecond-laser micromachining. The resulting waveguides are compatible with single-mode fibers and have the smallest insertion loss of 4.95 dB. On-demand light storage is demonstrated in a waveguide by employing the spin-wave atomic frequency comb (AFC) scheme and the revival of silenced echo (ROSE) scheme. We implement a series of interference experiments based on these two schemes to characterize the storage fidelity. Interference visibility of the readout pulse is 0.99 ± 0.03 for the spin-wave AFC scheme and 0.97 ± 0.02 for the ROSE scheme, demonstrating the reliability of the integrated optical memory.

A luminescent Eu, Dy: SrAl2O4 glass-ceramics with high transparency in the visible region was successfully synthesized using the frozen sorbet technique with the control of O2 partial pressure (PO2) for the oxidation of Eu2+ ions. The glass-ceramics include Eu2+, Eu3+, and Dy3+ ions, and thus exhibits three characteristic types of emission bands, 4f–5d at around 520 nm (Eu2+ ions), 4f–4f at 610 nm (Eu3+ ions), and 480 nm (Dy3+ ions). The Eu, Dy: SrAl2O4 glass-ceramics provide remarkable long-persistent luminescence under dark condition. The glass-ceramics also exhibits color-changing luminescence in the visible region based on their remarkable light storage properties. The luminescent Eu, Dy: SrAl2O4 glass-ceramics using the frozen sorbet technique with control of PO2 are promising materials for application in novel photonic and light storage materials.

Illumination during storage was proven to extend the storability of seedlings, but little attention has been given to the underlying mechanism. To determine how light conditions affect photosynthetic status in watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] plug seedlings, differences of stomatal development and relative photosynthetic characteristics of expanding new leaves when stored for 8 days at 15 °C in light at a photosynthetic photon flux (PPF) of 15 μmol·m−2·s−1 or darkness were investigated. The stomatal density (SD) increased with time to a peak and then decreased from the start of storage in light to the subsequent transplantation. Dark storage retarded the stomatal development and delayed the appearance of the peak of SD. Compared with those under dark storage, light-stored seedlings showed significantly higher SD and stomatal index (SI) in leaves accompanied by higher maximal photochemical efficiency of PSII (Fv/Fm) and quantum yield of PSII (ΦPSII). During storage in darkness, Fv/Fm and ΦPSII declined steeply with increasing storage duration but recovered gradually to reach the same level of those in light at the fourth day after transplanting. Seedlings stored in light for 8 days showed higher net photosynthesis rate (Pn), stomatal conductance (gS), intercellular CO2 concentration (Ci), and transpiration rate (Tr) than in darkness. The post-storage recovery of Pn, gS, and Tr were closely related to the SI, which ensured the fast recovery of photosynthesis during the early stage of transplanting. In agreement with the change of SD, no differences in Pn, gS, Ci, and Tr between light and dark storage were observed after 8 days of transplantation. Seedlings stored in light appeared vigorous and the shoot dry weight was significantly higher than that of dark-stored ones. Although seedlings in dark storage had a poor appearance during storage, they showed inhibited regrowth potentials during the subsequent transplanting stage. This study exhibited that light in short-term storage contributed to maintaining stomatal development as well as photosynthetic efficiency in watermelon, which could also extend to post-storage for ensuring the transplant quality of seedlings after removal from storage.

In this work, we demonstrate and evaluate the viability of SrAl2O4:Eu[Formula: see text], Dy[Formula: see text] crystals for long-term light storage applications at low temperatures that can be activated at higher temperatures for on-demand lighting applications. The switching mechanism is discussed from the point of view of the possible interplay between charge transport and the persistent luminescence in this system. Step-wise temperature-dependent luminescence decay time measurement is carried out to determine the optimal temperature for photo-charging and the operational temperature limit of the crystal-under-test as light sources.

In this paper, the influence of light storage and the exposure on quality parameters of a monovarietal extra virgin olive oil packaged in polyethylene terephthalate (PET) bottles were investigated. Coloured PET bottles (clear, green, orange, white and blue) were stored under different artificial lighting conditions in order to simulate the market environment (one fluorescent cool white lamp) and to perform an accelerated test (four fluorescent cool white lamps); storage in the dark was considered as a control. Total peroxide value, polyphenols, chlorophyll and carotenoids contents were, among the ones tested, the quality indexes most affected by lighting and were useful to investigate the bottle colour influence. Concerning the global quality of olive oil, under one fluorescent lamp, the best performances were obtained using blue and white PET bottles; whereas under accelerated conditions, the differences in the protection efficacy offered by the differently coloured bottles were reduced. Copyright © 2013 John Wiley & Sons, Ltd.

We propose a new method to create two-photon states in a controllable way using interaction between the Rydberg atoms during the storage and retrieval of slow light. A distinctive feature of the suggested procedure is that the slow light is stored into a superposition of two atomic coherences under conditions of electromagnetically induced transparency (EIT). Interaction between the atoms during the storage period creates entangled pairs of atoms in a superposition state that is orthogonal to the initially stored state. Restoring the slow light from this new atomic state one can produce a two photon state with a second-order correlation function determined by the atom-atom interaction and the storage time. Therefore the measurement of the restored light allows one to probe the atom-atom coupling by optical means with a sensitivity that can be increased by extending the storage time. As a realization of this idea we consider a many-body Ramsey-type technique which involves pi/2 pulses creating a superposition of Rydberg states at the beginning and the end of the storage period. In that case the regenerated light is due to the resonance dipole-dipole interaction between the atoms in the Rydberg states.