arXiv subjects

Aleš Stejskal

Publications and source records attributed to Aleš Stejskal.

2 recordsLinked to original sources

arXiv2025

Towards Flexible Intensity Control of Resonantly Scattered $γ$-Rays Using Multi-Frequency Vibrating Resonant Absorber

We report a method for coherent control of $γ$-photons, enabling the shaping of $γ$-ray intensity in nearly arbitrary waveforms. Different intensity waveforms are created by adjusting the motion profile of a resonant absorber (an ensemble of Mössbauer nuclei) and tuning the energy of the incident radiation. A crucial aspect of this method is the use of a low fundamental frequency of vibrations, which broadens the possibilities for $γ$-ray control. The results of numerical simulations are experimentally validated by generating single and double $γ$-pulses and inducing short-term absorption. For this, a resonant absorber containing $^{57}$Fe nuclei was vibrated with different motion profiles composed of 12 harmonics with a fundamental frequency of 1\,MHz. The proposed technique represents an advancement in the manipulation of $γ$-rays and potentially X-rays, paving the way for the performance of unique types of $γ$-ray or X-ray quantum experiments and the development of tools such as adjustable tabletop $γ$-pulse sources or $γ$-ray or X-ray delays and gates. Moreover, inverse application of the method enables investigation of motion at the picometer scale.

physics.ins-det↗

arXiv2021

Non-blocking programmable delay line with minimal dead time and tens of picoseconds jitter

We report a non-blocking high-resolution digital delay line based on an asynchronous circuit design. Field programmable gate array logic primitives were used as a source of delay and optimally arranged using combinatorial optimization. This approach allows for an efficient trade-off of the resolution and a delay range together with minimized dead time operation. We demonstrate the method by implementing the delay line adjustable from 23 ns up to 1635 ns with a resolution of 10 ps. We present a detailed experimental characterization of the device focusing on thermal instability, timing jitter, and pulse spreading, which represent three main issues of the asynchronous design. We found a linear dependence of the delay on the temperature with the slope of 0.2 ps/K per a logic primitive. We measured the timing jitter of the delay to be in the range of 7 ps - 165 ps, linearly increasing over the dynamic range of the delay. We reduced the effect of pulse spreading by introducing pulse shrinking circuits, and reached the overall dead time of 4 ns - 22.5 ns within the dynamic range of the delay. The presented non-blocking delay line finds usage in applications where the dead time minimization is crucial, and tens of picoseconds excess jitter is acceptable, such as in many advanced photonic networks.

physics.ins-det↗