The large capacity and robustness of information encoding in the temporal mode of photons is important in quantum information processing, in which characterizing temporal quantum states with high usability and time resolution is essential. We propose and demonstrate a direct measurement method of temporal complex wavefunctions for weak light at a single-photon level with subpicosecond time resolution. Our direct measurement is realized by ultrafast metrology of the interference between the light under test and self-generated monochromatic reference light; no external reference light or complicated post-processing algorithms are required. Hence, this method is versatile and potentially widely applicable for temporal state characterization.
Strong Spin-Motion Coupling in the Ultrafast Dynamics of Rydberg Atoms
Institute for Molecular Science, National Institutes of Natural Sciences（国立自然科学研究所分子科学研究所）；SOKENDAI (The Graduate University for Advanced Studies)（综合研究大学院大学）；Department of Basic Science, The University of Tokyo（东京大学基础科学系）；Department of Physics, Tokyo University of Science（东京理科大学物理系）
We propose a synthetic dimension for ultrafast free electrons based on the discrete energy sidebands in photon-induced near-field electron microscopy (PINEM). The PINEM synthetic dimension can offer a powerful way to coherently shape or modulate free-electron wavefunctions in systems such as ultrafast transmission electron microscopes, dielectric laser accelerators, and quantum free-electron lasers. As examples of this paradigm, we demonstrate Bloch oscillations, diffraction management, and linear optics effects such as Talbot self-imaging in the PINEM lattice. These effects show the potential…
In this work we study the spatio-temporal correlations of photons produced by spontaneous parametric down conversion. In particular, we study how the waists of the detection and pump beams impact on the spectral bandwidth of the photons. Our results indicate that this parameter is greatly affected by the spatial properties of the detection beam, while not as much by the pump beam. This allows for a simple experimental implementation to control the bandwidth of the biphoton spectra, which only entails modifying the optical configuration to collect the photons. Moreover, we have performed Hong-O…
Pulse-by-pulse programmable synthesis of ultrafast optical waveforms
East China Normal University（华东师范大学）；Chongqing Institute of East China Normal University（华东师范大学重庆研究院）；Polytechnique Montréal（蒙特利尔高等理工学院）；University of New Mexico（新墨西哥大学）
The photonic temporal degree of freedom is one of the most promising platforms for quantum communication over fiber networks and free-space channels. In particular, time-bin states of photons are robust to environmental disturbances, support high-rate communication, and can be used in high-dimensional schemes. However, the detection of photonic time-bin states remains a challenging task, particularly for the case of photons that are in a superposition of different time-bins. Here, we experimentally demonstrate the feasibility of picosecond time-bin states of light, known as ultrafast time-bins…
Time-bin qudits have emerged as a promising encoding platform in many quantum photonic applications. However, the requirement for efficient single-shot measurement of time-bin qudits instead of reconstructive detection has restricted their widespread use in experiments. Here, we propose an efficient method to measure arbitrary superposition states of time-bin qudits and confirm it up to dimension 4. This method is based on encoding time bins at the picosecond time scale, also known as ultrafast time bins. By doing so, we enable the use of robust and phase-stable single spatial mode temporal in…
Picosecond Schrödinger cat states for ultrafast optical quantum processing
The University of Tokyo（东京大学）；RIKEN Center for Quantum Computing（理化学研究所量子计算研究中心）；OptQC Inc.（OptQC公司）；National Institute of Advanced Industrial Science and Technology（国立研究开发法人产业技术综合研究所）；NTT Inc.（日本电信电话株式会社）；Johannes Gutenberg-Universität Mainz（美因茨约翰内斯·古腾堡大学）
Infinitely fast critical dynamics: Teleportation through temporal rare regions in monitored quantum circuits
Racah Institute of Physics, The Hebrew University of Jerusalem（拉卡物理学研究所，耶路撒冷希伯来大学）；Department of Electrical and Computer Engineering, Princeton University（电气与计算机工程系，普林斯顿大学）；Department of Physics, Princeton University（物理系，普林斯顿大学）；The Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem（分子动力学弗里茨·哈伯研究中心，耶路撒冷希伯来大学）；Department of Physics and Astronomy, Center for Materials Theory, Rutgers University（物理与天文学系，材料理论中心，罗格斯大学）；Center for Computational Quantum Physics, Flatiron Institute（计算量子物理中心，平顿研究所）
