Atomic wave packets loaded into a phase-modulated vertical optical-lattice potential exhibit a coherent delocalization dynamics arising from intraband transitions among Wannier-Stark levels. Wannier-Stark intraband transitions are here observed by monitoring the in situ wave-packet extent. By varying the modulation frequency, we find resonances at integer multiples of the Bloch frequency. The resonances show a Fourier-limited width for interrogation times up to 2 s. This can also be used to determine the gravity acceleration with ppm resolution.
In situ accurate determination of the zero time delay between two independent ultrashort laser pulses by observing the oscillation of an atomic excited wave packet
We present a multichannel photoelectron interferometry technique based on trichromatic pulse shaping for unambiguous determination of quantum phases in multiphoton ionization (MPI) of potassium atoms. The colors of the laser field are chosen to produce three energetically separated photoelectron interferograms in the continuum. While the red pulse is two-photon resonant with the $3d$-state resulting in a (2+1) resonance-enhanced MPI (REMPI), a (1+2) REMPI occurs via the non-resonant intermediate $4p$-state with an initial green or blue pulse. We show that ionization via a non-resonant intermed…
The quasicontinuum method was originally introduced to bridge across length scales -- from atomistics to significantly larger continuum scales -- thus overcoming a key limitation of classical atomic-scale simulation techniques while solely relying on atomic-scale input (in the form of interatomic potentials). An associated challenge lies in bridging across time scales to overcome the time scale limitations of atomistics. To address the biggest challenge, bridging across both length and time scales, only a few techniques exist, and most of those are limited to conditions of constant temperature…
We investigate the effect of degenerate atomic states on the exciton delocalization of dipole-dipole interacting Rydberg assemblies. Using a frozen gas and regular one-, two-, and three-dimensional lattice arrangements as examples, we see that degeneracies can enhance the delocalization compared to the situation when there is no degeneracy. Using the Zeeman splitting provided by a magnetic field, we controllably lift the degeneracy to study in detail the transition between degenerate and non-degenerate regimes.
Quantum time dilation occurs when a clock moves in a superposition of relativistic momentum wave packets. We utilize the lifetime of an excited hydrogen-like atom as a clock to demonstrate how quantum time dilation manifests in a spontaneous emission process. The resulting emission rate differs when compared to the emission rate of an atom prepared in a mixture of momentum wave packets at order $v^2/c^2$. This effect is accompanied by a quantum correction to the Doppler shift due to the coherence between momentum wave packets. This quantum Doppler shift affects the spectral line shape at order…
Pulse analysis by delayed absorption from a coherently excited atom
在本教程中，我们简要回顾了阿秒脉冲表征技术，并对最近提出的称为延迟吸收脉冲分析（PANDA）的方法进行了教学说明[Pabst and Dahlström，Phys. Rev. A，94，13411（2016）]。我们讨论了在碱金属原子中使用主量子数波包或自旋轨道波包实现PANDA的可能性。PANDA方法的主要优点是，它可以用作脉冲表征方法，不受原子延迟效应的影响，例如散射相移和长寿命原子共振。最后，我们建议，结合PANDA方法与角分辨光电子探测应允许实验测量阿秒延迟的光电离从约束波包的顺序上的几十阿秒。
Scattering of ultrashort electron wave packets: optical theorem, differential phase contrast and angular asymmetries
RIKEN Cluster for Pioneering Research (CPR) and RIKEN Center for Advanced Photonics (RAP), RIKEN（RIKEN前沿研究集群（CPR）和RIKEN先进光子学中心（RAP），理化学研究所）；Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo（东京大学工学研究科核工程与管理系）；Department of Physics and Astronomy, Aarhus University（奥胡斯大学物理与天文系）
