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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Storage and Retrieval of Electromagnetic Waves in Metamaterials by Dynamical Control of EIT-Like Effect
摘要： The storage of light is one of the most significant applications of electromagnetically induced transparency (EIT) effects in atomic systems. It is also possible to mimic the EIT effect using artificial media, or metamaterials, which are based on coupled resonators. This chapter focuses on metamaterials that realize the storage and retrieval of electromagnetic waves in the same way as the atomic EIT system. We introduce tunable metamaterials that are loaded with variable capacitors, which realize dynamical modulation of the EIT-like effects and the control of asymmetric spectra unique to the Fano resonance. Experiments are performed to show that electromagnetic waves are stored and released coherently in a multi-layered metamaterial designed for the operation in the microwave region. In addition, we show the frequency conversion of the stored waves and the extension of the storage time using parametric amplification.
关键词： Fano resonance,storage of electromagnetic waves,EIT,Electromagnetically induced transparency,parametric amplification,metamaterials
更新于2025-09-23 15:21:21
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Ytterbium laser system for studying parametric amplification of femtosecond pulses with a centre wavelength of a??2 ??m
摘要： A laser system is developed with an optical synchronisation of a femtosecond signal with a pump channel. The signal of a driving ytterbium fibre laser with a 60 MHz repetition rate of stretched femtosecond pulses is amplified in energy from several nanojoules to 0.4 mJ at a pulse repetition rate of 3 kHz in a wide-band amplifier and then is compressed in time to 250 fs. The obtained radiation is used for generating femtosecond laser pulses with a centre wavelength of ~2 mm, pulse energy of above 20 mJ, duration of several field oscillations, and phase stabilisation between the electromagnetic field and envelope. The other pulse of the driving fibre laser provides optical synchronisation and a minimal time delay and is directed to a regenerative Yb : YAG disk amplifier for amplification to an energy of 4 mJ at a pulse repetition rate of 3 kHz and duration of 20 ps. A multipass disk amplifier is developed for further increasing the energy of pump chirped pulses to an energy of 70 mJ at a pulse repetition rate of 10 Hz and duration of 400 ps for studying parametric amplification under sub-nanosecond pumping.
关键词： parametric amplification,Yb :YAG disk amplifier,ytterbium fibre laser,femtosecond pulses,pulse compression
更新于2025-09-23 15:19:57
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Fast Gate-Based Readout of Silicon Quantum Dots Using Josephson Parametric Amplification
摘要： Spins in silicon quantum devices are promising candidates for large-scale quantum computing. Gate-based sensing of spin qubits offers a compact and scalable readout with high fidelity, however, further improvements in sensitivity are required to meet the fidelity thresholds and measurement timescales needed for the implementation of fast feedback in error correction protocols. Here, we combine radio-frequency gate-based sensing at 622 MHz with a Josephson parametric amplifier, that operates in the 500–800 MHz band, to reduce the integration time required to read the state of a silicon double quantum dot formed in a nanowire transistor. Based on our achieved signal-to-noise ratio, we estimate that singlet-triplet single-shot readout with an average fidelity of 99.7% could be performed in 1 μs, well below the requirements for fault-tolerant readout and 30 times faster than without the Josephson parametric amplifier. Additionally, the Josephson parametric amplifier allows operation at a lower radio-frequency power while maintaining identical signal-to-noise ratio. We determine a noise temperature of 200 mK with a contribution from the Josephson parametric amplifier (25%), cryogenic amplifier (25%) and the resonator (50%), showing routes to further increase the readout speed.
关键词： quantum computing,spin qubits,gate-based sensing,silicon quantum dots,Josephson parametric amplification
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Broad-Band Optical Parametric Amplification in a Tapered Silicon Core Fiber Pumped in the Telecom Band
摘要： Silicon core ?bers (SCFs) are emerging as a robust and ?exible waveguide platform that can exploit the high nonlinear coef?cients of silicon to perform compact nonlinear processing within an integrated ?ber geometry. Optical parametric ampli?cation (OPA) based on four-wave mixing (FWM) has been studied intensively over the past decade using chip-based silicon waveguides for a variety of telecommunication applications such as all-optical signal sampling, time-demultiplexing, pulse generation, and wavelength conversion. However, due to the strong nonlinear absorption associated with two photon and free carrier effects in silicon at telecom wavelengths, net on/off parametric gain has not been observed using a continuous-wave (CW) signal, and even when using pulses the gain has been limited to be 5.2 dB. Here, by tapering the SCF to tailor the dimensions such that we can achieve high coupling ef?ciency into a core with a sub-micron-sized diameter, required to access the anomalous dispersion region, we demonstrate OPA with a positive on/off gain up to 6.6 dB and bandwidth of more than 220 nm. Eventually, when fully integrated with conventional ?bers and components to improve the robustness of the system, we expect these tapered SCFs will ?nd wide-ranging applications in areas that require ef?cient wavelength conversion across a broad spectral band.
关键词： optical parametric amplification,nonlinear absorption,Silicon core fibers,telecom wavelengths,four-wave mixing
更新于2025-09-11 14:15:04