hiː kəntɹˈɪbjuːɾᵻd tə ðə θˈiəɹi ʌv pˈoʊlæɹənz sˈiː ɹᵻvjˈuːz ɪn pɚtˈɪkjʊlɚ ðɛɹ ˈɑːptɪkəl ænd mˌæɡnɪtˈuːptɪkəl pɹˈɑːpɚɾiz, kwˈɔntəm θˈiəɹi ʌv sˈɑːlɪd mˈæɾɚ, sˌuːpɚkɑːndəktˈɪvᵻɾi ænd sˌuːpɚfluːˈɪdᵻɾi, fˈeɪnmən pˈæθ ˈɪntᵻɡɹəlz ænd mˌæθɪmˈæɾɪkəl mˈɛθədz stɹˈʌktʃɚz wɪð ɹᵻdˈuːst dᵻmˈɛnʃən ænd dᵻmˌɛnʃənˈælᵻɾi nˌænoʊfˈɪzɪks.
He contributed to the theory of polarons (see reviews in particular their optical and magnetooptical properties, quantum theory of solid matter, superconductivity and superfluidity, Feynman path integrals and mathematical methods structures with reduced dimension and dimensionality nanophysics).