Search

Abstract We explore light storage in antirelaxation-coated and buffer-gas-filled alkali vapor cells, employing electromagnetically induced transparency (EIT) in warm rubidium vapor. We conduct a comparative study of light storage performance under identical experimental conditions for these two cell types. Using a buffer-gas-filled cell resulted in approximately a tenfold improvement in memory efficiency and storage time compared to antirelaxation-coated cells. Moreover, we demonstrate that memory efficiency can be further enhanced by choosing a near-resonant EIT $$\Lambda$$ Λ -scheme over a resonant one. Our findings provide valuable insights for optimizing light storage, thereby contributing to the development of field-deployable quantum memories.

We explore light storage in antirelaxation-coated and buffer-gas-filled alkali vapor cells, employing electromagnetically induced transparency (EIT) in warm rubidium vapor. We conduct a comparative study of light storage performance under identical experimental conditions for these two cell types. Using a buffer-gas-filled cell resulted in approximately a tenfold improvement in memory efficiency and storage time compared to antirelaxation-coated cells. Moreover, we demonstrate that memory efficiency can be further enhanced by choosing a near-resonant EIT Λ -scheme over a resonant one. Our findings provide valuable insights for optimizing light storage, thereby contributing to the development of field-deployable quantum memories. [ABSTRACT FROM AUTHOR]

• The magnetic field is utilized as a "knob" to manipulate the optical response of the degenerate four-level atomic medium. • The amplitude and sign of the group index are adjusted by the strength or the direction of the magnetic field. • We can switch between fast and slow light propagation by turning the static magnetic field on or off. • The influence of the Doppler effect on optical response and the group index is significant. We study slow and fast light propagation through a static magnetic field at room temperature in a degenerate four-level atomic medium. The probe field absorption spectrum and group index are controllable according to the static magnetic field and the coupling field pair under the electromagnetically induced transparency condition. When one or both coupling fields are turned on simultaneously, we can use the magnetic field as a tuning "knob" to change the optical response of the atomic medium from transparent to absorbing or vice versa. Accordingly, the amplitude and sign of the group index also change from positive to negative or vice versa under the on/off of the magnetic field. Furthermore, temperature's influence on the atomic medium's optical response and the group index is significant. Our proposed model is applied at room temperature, making the results close to reality and thus may be helpful in optical storage and quantum information processing. [ABSTRACT FROM AUTHOR]

We present the experimental demonstration of light storage towards the single photon level at a long storage time by electromagnetically induced transparency in a rare-earth ion-doped Pr ^3+ :Y _2 SiO _5 crystal. We apply decoherence control by static magnetic fields and appropriately designed radio-frequency composite pulse sequences to prolong the storage time in the memory. A rare-earth ion-doped filter crystal prepared by optical pumping serves to efficiently separate the signal at the single photon level from optical noise. Multipass setups around the memory and the filter crystal improve the storage efficiency and filter selectivity. Already without decoherence control, the setup permits storage of single photons in the microsecond regime at a storage efficiency of 42%. With decoherence control we demonstrate storage of weak coherent pulses containing some 10 photons for up to 10 s at a storage efficiency of several percent. The experimental data clearly demonstrate the applicability of EIT light storage to implement a true quantum memory in Pr ^3+ :Y _2 SiO _5 at long storage times. The scientific findings and technical developments are of relevance also to other protocols and media for quantum information storage.

We report on improved light storage efficiency in a hot rubidium atomic vapor cell achieved using an additional pump field for optical pumping to a target state. When this targetable optical pumping is applied to light storage based on an electromagnetically induced transparency (EIT) configuration with orthogonal polarizations, the light storage efficiency increases to three times that of the EIT storage without optical pumping. The cause of this improvement in the light storage efficiency is targetable optical pumping to a specific Zeeman sub-state, which makes the pump field necessary in order to achieve a complete EIT scheme. [ABSTRACT FROM AUTHOR]

Controlling the flow of light on-chip is of great importance for quantum computing and optical signal processing. In this paper, we present a theoretical study to reveal the underlying physics of how to effectively trap, store and release a signal pulse, and eventually break the delay-bandwidth limit, based on controllable EIT-like effect in dynamically tuned standing-wave cascaded nanocavities. Using this mechanism, we design a compact silicon photonic crystal system with long storing time and a delay-bandwidth product over 460, which is about two orders of magnitude greater than the reported results obtained by other methods based on static resonator system, and the trapped signal pulse can be released on demand.

In the framework of the coupled mode theory we consider light trapping between two off-channel resonators which serve as self-adjusted Fano mirrors due to the Kerr effect. By inserting an auxiliary nonlinear resonator between the mirrors we achieve self-tuning of phase shift between the mirrors. That allows for the light trapping for arbitrary distance between the mirrors. [ABSTRACT FROM AUTHOR]

By using slow and stored light based on electromagnetically induced transparency (EIT), we theoretically realize the storage of optical pulses with enhanced efficiency and high fidelity in ensembles of warm atoms in 85 Rb vapor cells. The enhancement of storage efficiency is achieved by introducing a pump field beyond three-level configuration to form a N-type scheme, which simultaneously inhibits the undesirable four-wave mixing effect while preserves its fidelity. It is shown that the typical storage efficiency can be improved from 29% to 53% with the application of pump field. Furthermore, we demonstrate that this efficiency decreases with storage time and increases over unity with optical depth. [ABSTRACT FROM AUTHOR]

Using atomic motion to coherently spread light information stored in atoms provides a means to manipulate atom-light interactions. We demonstrate light splitting with moving atoms in a paraffin-coated vapor cell by using phase-sensitive degenerate four-wave mixing, or self-rotation. This scheme amplifies the slow light beam splitter signal, and, in the meantime, maintains the phase coherence between the beam-splitter channels. Light storage efficiency in the beam-splitting channel can also be enhanced. Furthermore, we demonstrate an optical memory exceeding 1 s, taking advantage of the gain from self-rotation and an atomic coherence composed of a fast-decaying part and a slow-decaying part. These results should find applications in optical memory, optical routers, and atomic coherence control. [ABSTRACT FROM AUTHOR]

The rectangular spectrum of sinc-shaped Nyquist pulses enables the encoding of data in a minimum spectral width. Sinc pulses can improve optical sampling devices, could enable the implementation of ideal rectangular microwave photonics filters, and can be used for all-optical signal processing, spectroscopy, and light storage. Recently, the generation of sinc-pulse sequences with extraordinary quality was shown by the utilization of cascaded modulators. However, the line width and repetition rate of the pulses is limited by the modulator bandwidth. Here, we present the nonrestricted generation of flexible Nyquist pulse sequences. Therefore, multiple single lines of a comb generator are extracted with optical filters and subsequently processed by cascaded modulators. In a first proof-of-concept experiment, we achieved almost ideally sinc-shaped Nyquist pulses with a bandwidth of 286 GHz, a pulse width of 3.5 ps, and a duty cycle of 2.2%. However, sinc-shaped Nyquist pulse sequences in the femtosecond range with terahertz bandwidths would be possible with the method. [ABSTRACT FROM PUBLISHER]

Light can be invoked as a signal for improving metabolism and physiological state during plant storage. However, little is known about the effects of light on volatile flavor compounds and sensory properties during melon fruit storage, especially for different types of visible light. Fifty typical volatile flavor compounds, including 28 esters, 7 alcohols, 7 aldehydes, 4 ketones, 2 furans, 1 ether, and 1 pyrazine, were identified by gas chromatography–ion mobility spectrometry in melon fruit under blue light, black, green light, red light, and white light storage conditions. The total peak values of the flavor compounds were significantly higher in white light storage condition but significantly lower in black storage condition compared with the controls. A 5-day continuous sensory property study involving color, appearance, freshness, odor, and mouthfeel was performed. Total sensory scores were high in white light storage conditions but low in black storage conditions. The results were consistent with the previous detection results, and white light was found to be more conducive to melon storage. This study provides useful insights into the effects of light on flavor and sensory properties of melon fruit, as well as a possible way to extend melon fruit shelf life by visible light irradiation. [ABSTRACT FROM AUTHOR]

Abstract: It was numerically demonstrated that a 2-ns-long Gaussian shaped and a 2-ns-long rectangular shaped data-pulse are fully retrieved as original via stimulated Brillouin scattering light storage process in an optical fiber. Zero-broadening without distortion data-pulse light storage is realized. In our study, for a given data-pulse, there are two conditions for it is fully retrieved: (1) the spectrum of the control-pulse is engineered so that the spectral width of the pulses is changed, making possible to match at best the data-pulse spectrum. (2) control-pulse temporal distribution profile must be suitable for the data-pulse. We also proved that the readout efficiency of completely retrieved data-pulse is the biggest. Because the Gaussian shaped data-pulse relative optical spectral bandwidth is the narrowest, it is easier to be retrieved. [Copyright &y& Elsevier]

Abstract: A photon being a carrier of a polarization qubit is stored inside an atomic medium in the tripod configuration in the form of atomic excitations. Such stored information can be processed in the atomic memory and carried away by the released photon. An implementation is proposed of single qubit gates, e.g., phase, NOT, and Hadamard, as well as for a two-qubit CNOT gate, operating on polarized photons and based on light storage. [Copyright &y& Elsevier]

We experimentally study the generation and storage of double slow light pulses in a Pr3+:Y2SiO5 crystal. Under electromagnetically induced transparency, a single signal pulse is stored in the spin coherence of the crystal. By simultaneously switching on two control fields to recall the stored information, the spin coherence is converted into two slow light pulses with distinct frequencies. Furthermore, the storage and controlled retrieval of double slow light pulses are obtained by manipulating the control fields. This study of double slow light pulses may have practical applications in information processing and all-optical networks. [ABSTRACT FROM AUTHOR]

Abstract: The pulse compression effect in SBS light storage is numerically investigated. We demonstrate theoretically that the compressed width of retrieved data-pulses is not only related with temporal profile of data-pulse, but also spectrum and temple profile of control-pulse. The data-pulses with steep rising edge can be compressed after they are retrieved. The optimum compression effect takes place when a 2-ns-long exponential data-pulse interacts with a 1.5-ns-long chirped Gaussian control-pulse, where the data-pulse width is compressed to 1.73-ns-long and the readout efficiency is the biggest. A 2-ns-long rectangular data-pulse is also compressed to 1.73-ns-long when it encounters to a 1.5-ns-long rectangular control-pulse, but the readout efficiency isn’t maximum value. The results are significant for increasing storage capacity and variable bits all-optical buffering. [Copyright &y& Elsevier]

We have theoretically investigated the phase shift of a probe field for a four-level atomic system interacting successively with two fields tuned near an EIT resonance of an atom, a microwave field, and a coupling field. It has been found that the phase of retrieved signal has been shifted due to the cross-phase modulation when the stored spin wave was disturbed by a microwave. Because of the low relaxation rates of the ground hyperfine state, our proposed technique can impart a large phase rotation onto the probe field with low absorption of retrieved field and very low intensity of the microwave field. [ABSTRACT FROM AUTHOR]

Waveguides that are composed of electromagnetically coupled optical microcavities [coupled resonator optical waveguides (CROWs)] can be used for light guiding, slowing, and storage. In this paper, we present a 2-D analysis of finite-size straight and curved CROW sections based on a rigorous Muller boundary integral equation method. We study the mechanisms of the coupling of whispering-gallery (WG) mode and guiding light around bends in CROWs composed of both identical and size- mismatched microdisk resonators. Our accurate analysis reveals the differences in WG modes coupling in the vicinity of bends in CROWs composed of optically large and wavelength-scale micro- cavities. We propose and discuss possible ways to design low-loss CROW bends and to reduce bend losses. These include selecting specific bend angles depending on the azimuthal order of the WG mode and tuning the radius of the microdisk positioned at the CROW bend. [ABSTRACT FROM PUBLISHER]

Abstract: We experimentally demonstrate a light storage via slow-light four-wave mixing in a solid-state medium with a four-level double lambda scheme. Using slow light based on electromagnetically induced transparency, we obtain a slowed four-wave mixing signal pulse together with the slowed probe pulse. During the propagation of light pulses, the storage and retrieval of both the slowed four-wave mixing pulse and the slowed probe pulse are studied by manipulating the intensities of the control fields. [Copyright &y& Elsevier]