Theory on radiation dynamics of biexciton in thin film and its entangled photon generation

• Project/Area Number: 16K05403
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Tokyo Denki University
• Principal Investigator: AJIKI Hiroshi 東京電機大学, 理工学部, 教授 (60283735)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000); Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 量子もつれ光子対 / 励起子分子 / 表面励起子ポラリトン / 量子井戸 / 励起子

Outline of Final Research Achievements

An entangled photon pair is a key resource of quantum information technologies. The entangled photon pair can be generated from the radiative decay of a biexciton. For a semiconductor film, one of the final states of the biexciton decay processes is a surface exciton polariton, which cannot emit a photon, i.e., entangled photons cannot be generated via the surface polariton.
In this study, I calculate the transition rate from the biexciton to the surface polariton, which cannot contribute to the entangled photon generation. For this purpose, photon and exciton components consisting the surface polariton are numerically obtained, which has not been calculated so far. I also calculate the transition rate to the exciton and photon, in which entangled photons are generated. By calculating the thickness dependence of each transition rate, an optimum thickness of the film is found for the entangled photon generation.

Academic Significance and Societal Importance of the Research Achievements

量子情報処理技術の実用化に向けて様々な量子もつれ状態が提案されているが，量子もつれ光子対は環境からの影響が極めて小さい点に長所がある．もつれ光子対の実験の多くは量子ドットを利用しているが，光と物質系の相互作用が強くなる薄膜の方が効率よくもつれ光子対を生成できると考えられる．本研究では，量子もつれ光子対の生成効率に最適な膜厚が存在することを示し，その計算方法を明らかにしている点で意義がある．

Research Products

• [Journal Article] Biexciton relaxation associated with dissociation into a surface polariton pair in semiconductor films (2018)
  • Author(s): Mitsumori Yasuyoshi、Matsuura Shimpei、Uchiyama Shoichi、Saito Kentarao、Edamatsu Keiichi、Nakayama Masaaki、Ajiki Hiroshi
  • Journal Title: Physical Review B Volume: 97 Issue: 15
  • DOI: 10.1103/physrevb.97.155303
  • Peer Reviewed
• [Journal Article] 薄膜における励起子分子の輻射緩和 (2016)
  • Author(s): 安食博志
  • Journal Title: 第２７回光物性研究会論文集 Volume: 27 Pages: 207-210
• [Presentation] Biexciton Radiative Decay to Surface Exciton Polariton (2018)
  • Author(s): H. Ajiki, Y. Mitsumori, S. Matsuura, S. Uchiyama, M. Sadgrove, K. Edamatsu
  • Organizer: EXCITON2018
  • Int'l Joint Research
• [Presentation] Thickness Dependence of Radiative Decay Time of Biexciton in Thin Film: Efficiency of Entangled Photon Generation (2017)
  • Author(s): H. Ajiki
  • Organizer: International Conference on Optics of Exciton in Confined Systems (OECS2017)
  • Int'l Joint Research
• [Presentation] CuCl薄膜中の励起子分子のエネルギー緩和時間の膜厚依存性II (2017)
  • Author(s): 三森康義、内山将一、枝松圭一、植田誠史、中山正昭、安食博志
  • Organizer: 日本物理学会秋季大会
• [Presentation] 薄膜における励起子分子の輻射緩和 (2016)
  • Author(s): 安食博志
  • Organizer: 第２７回光物性研究会
  • Place of Presentation: 神戸大学（兵庫県神戸市）
  • Year and Date: 2016-12-02
• [Presentation] 薄膜における励起子分子の輻射寿命の膜厚依存性 (2016)
  • Author(s): 安食博志
  • Organizer: 日本物理学会２０１６年秋季大会
  • Place of Presentation: 金沢大学（石川県金沢市）
  • Year and Date: 2016-09-13