【公開日：2025.06.10】【最終更新日：2025.04.22】
課題データ / Project Data
課題番号 / Project Issue Number
24QS0004
利用課題名 / Title
Exploring Purcell effects of nuclei in a multimode x-ray cavity quantum electrodynamics system
利用した実施機関 / Support Institute
量子科学技術研究開発機構 / QST
機関外・機関内の利用 / External or Internal Use
外部利用/External Use
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）量子・電子制御により革新的な機能を発現するマテリアル/Materials using quantum and electronic control to perform innovative functions（副 / Sub）-
キーワード / Keywords
原子薄膜/ Atomic thin film,量子効果/ Quantum effect,放射光/ Synchrotron radiation,メスバウアー分光/ Mossbauer spectroscopy,フォトニクス/ Photonics
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
Kong Xiangjin
所属名 / Affiliation
Institute of Modern Physics, Fudan University
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
増田 亮,Xu Wei,Zhang Yujun,Cui Zinan,Xia Kangjun,Xue Nan,Wan Yunyu,Guo Zhiying,Jin Shuoxue,Li Qiuju
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
三井 隆也,藤原 孝将
利用形態 / Support Type
（主 / Main）共同研究/Joint Research（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
Cavity quantum electrodynamics (cQED) has provided a platform for studying light-matter interactions, leading to the construction of quantum networks and fundamental tests of quantum mechanics [1]. While cQED studies have traditionally focused on the coupling to a single cavity mode [2], there is a growing interest in extending cQED to many cavity modes (multimode cQED). Multimode cQED holds the promise of exploring quantum many-body physics in dissipative systems, such as creating effective photon-mediated interactions between emitters [3].On the other hand, the Purcell effect [4], which refers to the modification of emitter decay rates induced by a cavity mode, has been a fundamental topic in cQED. It serves as a standard metric for various applications in nanophotonics, including the generation of broadband single-photon sources and nanolasers. While the Purcell effect has been extensively investigated in single-mode cQED systems [5], its study in multimode cQED systems is currently lacking. Here, we propose a strategy to explore the Purcell effects in an emerging cQED platform that focuses on x-ray-nuclei interactions [6]. Our approach involves placing a layer of 57Fe, exhibiting a Mössbauer transition resonant to x-ray radiation, in a thin-film x-ray cavity composed of absorptive mediums. This open and dissipative environment provides an opportunity to study the Purcell effects of nuclei in a multimode cQED system.The Purcell effect of nuclei can be modified by the resonant energies of cavity modes, and the coupling strengths between the nuclei and cavity modes. We expect to observe a distinct line shape depicting the relationship between the decay rate and the resonant energies of the cavity modes, which can be extracted from the energy spectrum of the system. This study will pave the way for investigating many-body physics in multimode cQED systems in the x-ray regime, making significant contributions to the fields of x-ray quantum optics and photonics. The methods developed in this project also carry the potential for broader applications, particularly in advancing the study of thin-film magnetic materials through Mössbauer techniques.Our long-term vision is to develop the first generation of sophisticated x-ray photonic devices that efficiently control x-ray quanta for use as information carriers or x-ray qubits, which holds the promise of unlocking new avenues for leveraging Mössbauer nuclei and x-ray photons in the realms of quantum communication, simulation, and computing. The study of multimode cQED systems offers a means of achieving this goal. Mössbauer nuclei, such as 57Fe, are particularly promising systems for realizing Purcell effects in multimode cQED in the x-ray regime due to their exceptional cleanliness as quantum optical systems.
実験 / Experimental
The Nuclear Resonant Scattering experiment in the energy domain was conducted at the BL11XU beamline using the Synchrotron Mössbauer Source (SMS). A high heat-load monochromator, followed by a nested high-resolution monochromator, was utilized to achieve an energy resolution of approximately 2 meV. The incident energy was set to 14.4125 keV for 57Fe. A silicon crystal collimator was employed to reduce the divergence angle of the incident beam before reaching the sample. The measurement was performed in a reflection geometry configuration, where the sample holder was equipped with a theta rotation stage, and the detector was mounted on a 2-theta rotation stage, enabling a theta-2-theta scan. Reflectivity curves were initially measured for incident angles ranging from 0 to 1 degree to determine the real structure and roughness of the thin-film samples and identify the precise angles required for subsequent NRS measurements.The thin-film samples consisted of a Pt and B4C sandwich structure with an embedded stainless steel layer enriched with 57Fe. The samples were fabricated using sputter deposition on sapphire wafers. Based on prior theoretical calculations, the required incident angles were around 0.2 degrees. Each sample was measured at eight different incident angles using NaI(Tl) detectors.The experiment proceeded as planned. Reflectivity curves were measured beforehand to confirm the appropriate incident angles and ensure sufficient suppression of electronic reflectivity. The entire experiment was completed within the allocated 12 shifts, including setup alignment, sample switching, and data acquisition.
結果と考察 / Results and Discussion
The energy-domain NRS spectra were recorded for the thin-film samples. However, significant noise arising from the motion of the SMS affected the measurements. As a reference, one dataset was fitted using our theoretical model, as shown in Fig.~1. While the fitting is reasonable, the noise level remains high. We are currently developing new methods to analyze the acquired data, which will undergo further processing to extract detailed insights into nuclear resonance effects in the thin-film samples.
図・表・数式 / Figures, Tables and Equations
Fig. 1
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
Reference:
[1] S. Haroche and D. Kleppner, Phys. Today 42, 24 (1989).
[2] J.-M. Raimond, M. Brune, and S. Haroche, Reviews of Modern Physics 73, 565 (2001).
[3] V. D. Vaidya et al., Phys. Rev. X 8, 011002 (2018).
[4] E. M. Purcell, Phys. Rev. 69, 681 (1946).
[5] R. Röhlsberger, K. Schlage, B. Sahoo, S. Couet, and R. Rüffer, Science 328, 1248 (2010).
[6] D. Lentrodt, O. Diekmann, C. H. Keitel, S. Rotter, and J. Evers, Phys. Rev. Lett. 130, 263602 (2023).
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件