[1] R. Zimmermann, K. Kilimann, W. D. Kraeft, D. Kremp, and G. R¨opke, “Dynamical Screening and Self-Energy of Excitons in the Electron-Hole Plasma,” Phys. Stat. Sol. B 90, 175 (1978).
[2] H. Stolz and R. Zimmermann, “Correlated Pairs and a Mass Action Law in Two-Component Fermi Systems,” Phys. Stat. Sol. B 94, 135 (1979).
[3] R. Zimmermann and H. Stolz, “The Mass Action Law in Two-Component Fermi Systems Revis- ited,” Phys. Stat. Sol. B 131, 151 (1985).
[4] D. Guerci, M. Capone, and M. Fabrizio, “Exciton Mott transition revisited,” Phys. Rev. Materials 3, 054605 (2019).
[5] J. M. Blatt, K. W. B¨oer, and W. Brandt, “Bose-Einstein Condensation of Excitons,” Phys. Rev. 126, 1691 (1962).
[6] L. V. Keldysh and A. N. Kozlov, Zh. Eksp. Teor. Fiz. 54, 978 (1968) [“Collective Properties of Excitons in Semiconductors,” Sov. Phys. JETP 27, 521 (1968)].
[7] E. Hanamura and H. Haug, “Condensation Effects of Excitons,” Phys. Rep. 33, 209 (1977).
[8] J. Bardeen, L. N. Cooper, and J. R. Schrieffer, “Theory of Superconductivity,” Phys. Rev. 108, 1175 (1957).
[9] L. V. Keldysh and Yu. V. Kopaev, Fiz. Tverd. Tela 6, 2791 (1964) [“Possible Instability of the Semimetallic State toward Coulomb Interaction,” Sov. Phys. Solid State 6, 2219 (1965)].
[10] D. J´erome, T. M. Rice, and W. Kohn, “Excitonic Insulator,” Phys. Rev. 158, 462 (1967).
[11] C. Comte and P. Nozi`eres, “Exciton Bose condensation: the ground state of an e-h gas I. Mean field description of a simplified model,” J. Phys. 43, 1069 (1982).
[12] P. Nozi`eres and S. Schmitt-Rink, “Bose Condensation in an Attractive Fermion Gas: From Weak to Strong Coupling Superconductivity,” J. Low Temp. Phys. 59, 195 (1985).
[13] E. Fortin, S. Fafard, and A. Mysyrowicz, “Exciton Transport in Cu2O: Evidence for Excitonic Superfluidity?” Phys. Rev. Lett. 70, 3951 (1993).
[14] J. L. Lin and J. P. Wolfe, “Bose-Einstein Condensation of Paraexcitons in Stressed Cu2O,” Phys. Rev. Lett. 71, 1222 (1993).
[15] K. Yoshioka, E. Chae, and M. Kuwata-Gonokami, “Transition to a Bose-Einstein condensate and relaxation explosion of excitons at sub-Kelvin temperatures,” Nat. Commun. 2, 328 (2011).
[16] D. C. Dai and A. P. Monkman, “Observation of superfluorescence from a quantum ensemble of coherent excitons in a ZnTe crystal: Evidence for spontaneous Bose-Einstein condensation of excitons,” Phys. Rev. B 84, 115206 (2011).
[17] M. E. Flatt´e, E. Runge, and H. Ehrenreich, “Coherent exciton lasing in ZnSe/ZnCdSe quantum wells?” Appl. Phys. Lett. 66, 1313 (1995).
[18] P. P. Vasil’ev, H. Kan, H. Ohta, and T. Hiruma, “Condensation of Electron-Hole Pairs in Bulk GaAs at Room Temperature under Conditions of Femtosecond Cooperative Emission,” J. Exp. Theor. Phys. 93, 1288 (2001).
[19] P. P. Vasil’ev, H. Kan, H. Ohta, and T. Hiruma, “Experimental evidence of condensation of electron-hole pairs at room temperature during femtosecond cooperative emission,” Phys. Rev. B 64, 195209 (2001).
[20] P. P. Vasil’ev, H. Kan, H. Ohta, and T. Hiruma, “Properties of electrons and holes during fem- tosecond cooperative emission,” Quantum Electron. 31, 870 (2001).
[21] P. P. Vasil’ev, H. Kan, H. Ohta, and T. Hiruma, “Coherent Electron-Hole BCS State: Study of Dynamics,” J. Exp. Theor. Phys. 96, 310 (2003).
[22] P. P. Vasil’ev and I. V. Smetanin, “Condensation of electron-hole pairs in a degenerate semicon- ductor at room temperature,” Phys. Rev. B 74, 125206 (2006).
[23] L.V. Butov, A. Zrenner, G. Abstreiter, G. B¨ohm, and G. Weimann, “Condensation of Indirect Excitons in Coupled AlAs/GaAs Quantum Wells,” Phys. Rev. Lett. 73, 304 (1994).
[24] L.V. Butov, A. L. Ivanov, A. Imamoglu, P. B. Littlewood, A. A. Shashkin, V. T. Dolgopolov, K. L. Campman, and A. C. Gossard, “Stimulated Scattering of Indirect Excitons in Coupled Quantum Wells: Signature of a Degenerate Bose-Gas of Excitons,” Phys. Rev. Lett. 86, 5608 (2001).
[25] L. V. Butov, A. C. Gossard, and D. S. Chemla, “Macroscopically ordered state in an exciton system,” Nature 418, 751 (2002).
[26] J. P. Eisenstein and A. H. MacDonald, “Bose–Einstein condensation of excitons in bilayer electron systems,” Nature 432, 691 (2004).
[27] H. Deng, G. Weihs, C. Santori, J. Bloch, Y. Yamamoto, “Condensation of Semiconductor Micro- cavity Exciton Polaritons,” Science 298, 199 (2002).
[28] J. Kasprzak, M. Richard, S. Kundermann, A. Baas, P. Jeambrun J. M. J. Keeling, F. M. Marchetti, M. H. Szyman´ska, R. Andr´e, J. L. Staehli, V. Savona, P. B. Littlewood, B. Deveaud, and L. S. Dang, “Bose–Einstein condensation of exciton polaritons,” Nature 443, 409 (2006).
[29] S. Utsunomiya, L. Tian, G. Roumpos, C. W. Lai, N. Kumada, T. Fujisawa, M. Kuwata-Gonokami, A. L¨offler, S. H¨ofling, A. Forchel, and Y. Yamamoto, “Observation of Bogoliubov excitations in exciton-polariton condensates,” Nat. Phys. 4, 700 (2008).
[30] T. Byrnes, N. Y. Kim, and Y. Yamamoto, “Exciton–polariton condensates,” Nat. Phys. 10, 803 (2014).
[31] Y. Sun, P. Wen, Y. Yoon, G. Liu, M. Steger, L. N. Pfeiffer, K. West, D. W. Snoke, and K. A. Nelson, “Bose-Einstein Condensation of Long-Lifetime Polaritons in Thermal Equilibrium,” Phys. Rev. Lett. 118, 016602 (2017).
[32] C. A. Regal, M. Greiner, and D. S. Jin, “Observation of Resonance Condensation of Fermionic Atom Pairs,” Phys. Rev. Lett. 92, 040403 (2004).
[33] M. W. Zwierlein, C. A. Stan, C. H. Schunck, S. M. F. Raupach, A. J. Kerman, and W. Ketterle, “Condensation of Pairs of Fermionic Atoms near a Feshbach Resonance,” Phys. Rev. Lett. 92, 120403 (2004).
[34] S. Giorgini, L. P. Pitaevskii, and S. Stringari, “Theory of ultracold atomic Fermi gases,” Rev. Mod. Phys. 80, 1215 (2008).
[35] M. Randeria and E. Taylor, “Crossover from Bardeen-Cooper-Schrieffer to Bose-Einstein Conden- sation and the Unitary Fermi Gas,” Annu. Rev. Condens. Matter Phys. 5, 209 (2014).
[36] M. Yamaguchi, K. Kamide, R. Nii, T. Ogawa, and Y. Yamamoto, “Second Thresholds in BEC- BCS-Laser Crossover of Exciton-Polariton Systems,” Phys. Rev. Lett. 111, 026404 (2013).
[37] V.-N. Phan, K. W. Becker, and H. Fehske, “Ground-state and spectral signatures of cavity exciton- polariton condensates,” Phys. Rev. B 93, 075138 (2016).
[38] T. Horikiri, M. Yamaguchi, K. Kamide, Y. Matsuo, T. Byrnes, N. Ishida, A. L¨offler, S. H¨ofling, Y. Shikano, T. Ogawa, A. Forchel, and Y. Yamamoto, “High-energy side-peak emission of exciton- polariton condensates in high density regime,” Sci. Rep. 6, 25655 (2016).
[39] T. Horikiri, T. Byrnes, K. Kusudo, N. Ishida, Y. Matsuo, Y. Shikano, A. L¨offler, S. H¨ofling, A. Forchel, and Y. Yamamoto, “Highly excited exciton-polariton condensates,” Phys. Rev. B 95, 245122 (2017).
[40] J. Hu, Z. Wang, S. Kim, H. Deng, S. Brodbeck, C. Schneider, S. H¨ofling, N. H. Kwong, and R. Binder, “Signatures of a Bardeen-Cooper-Schrieffer Polariton Laser,” arXiv:1902.00142.
[41] Y. Lubashevsky, E. Lahoud, K. Chashka, D. Podolsky, and A. Kanigel, “Shallow pockets and very strong coupling superconductivity in FeSexTe1−x,” Nat. Phys. 8, 309 (2012).
[42] K. Okazaki, Y. Ito, Y. Ota, Y. Kotani, T. Shimojima, T. Kiss, S. Watanabe, C.-T. Chen, S. Niitaka, T. Hanaguri, H. Takagi, A. Chainani, and S. Shin, “Superconductivity in an electron band just above the Fermi level: possible route to BCS-BEC superconductivity,” Sci. Rep. 4, 4109 (2014).
[43] K. Akiba, A. Miyake, H. Yaguchi, A. Matsuo, K. Kindo, and M. Tokunaga, “Possible Excitonic Phase of Graphite in the Quantum Limit State,” J. Phys. Soc. Jpn. 84, 054709 (2015).
[44] Z. Zhu, R. D. McDonald, A. Shekhter, B. J. Ramshaw, K. A. Modic, F. F. Balakirev, and N. Harrison, “Magnetic field tuning of an excitonic insulator between the weak and strong coupling regimes in quantum limit graphite,” Sci. Rep. 7, 1733 (2017).
[45] K. Seki, Y. Wakisaka, T. Kaneko, T. Toriyama, T. Konishi, T. Sudayama, N. L. Saini, M. Arita,H. Namatame, M. Taniguchi, N. Katayama, M. Nohara, H. Takagi, T. Mizokawa, and Y. Ohta, “Excitonic Bose-Einstein condensation in Ta2NiSe5 above room temperature,” Phys. Rev. B 90, 155116 (2014).
[46] Y. F. Lu, H. Kono, T. I. Larkin, A. W. Rost, T. Takayama, A. V. Boris, B. Keimer, and H. Takagi, “Zero-gap semiconductor to excitonic insulator transition in Ta2NiSe5,” Nat. Commun. 8, 14408 (2017).
[47] S. Mor, M. Herzog, D. Goleˇz, P. Werner, M. Eckstein, N. Katayama, M. Nohara, H. Takagi, T. Mizokawa, C. Monney, and J. St¨ahler, “Ultrafast Electronic Band Gap Control in an Excitonic Insulator,” Phys. Rev. Lett. 119, 086401 (2017).
[48] K. Okazaki, Y. Ogawa, T. Suzuki, T. Yamamoto, T. Someya, S. Michimae, M. Watanabe, Y. Lu, M. Nohara, H. Takagi, N. Katayama, H. Sawa, M. Fujisawa, T. Kanai, N. Ishii, J. Itatani, T. Mizokawa, and S. Shin, “Photo-induced semimetallic states realised in electron–hole coupled insulators,” Nat. Commun. 9, 4322 (2018).
[49] A. Kogar, M. S. Rak, S. Vig, A. A. Husain, F. Flicker, Y. I. Joe, L. Venema, G. J. MacDougall, T. C. Chiang, E. Fradkin, J. van Wezel, and P. Abbamonte, “Signatures of exciton condensation in a transition metal dichalcogenide,” Science 358, 1314 (2017).
[50] D. J. Campbell, C. Eckberg, P. Y. Zavalij, H.-H. Kung, E. Razzoli, M. Michiardi, C. Jozwiak, A. Bostwick, E. Rotenberg, A. Damascelli, and J. Paglione, “Intrinsic insulating ground state in transition metal dichalcogenide TiSe2,” Phys. Rev. Materials 3, 053402 (2019).
[51] H. Hedayat, C. J. Sayers, D. Bugini, C. Dallera, D. Wolverson, T. Batten, S. Karbassi, S. Friede- mann, G. Cerullo, J. van Wezel, S. R. Clark, E. Carpene, and E. Da Como, “Excitonic and lattice contributions to the charge density wave in 1T -TiSe2 revealed by a phonon bottleneck,” Phys. Rev. Research 1, 023029 (2019).
[52] T. Suzuki and R. Shimano, “Exciton Mott Transition in Si Revealed By Terahertz Spectroscopy,” Phys. Rev. Lett. 109, 046402 (2012).
[53] F. Sekiguchi and R. Shimano, “Excitonic correlation in the Mott crossover regime in Ge,” Phys. Rev. B 91, 155202 (2015). 78, 593 (2004).
[54] 関口文哉、「テラヘルツ分光法による励起子モット転移近傍の電子正孔相関の研究」、博士学位論文、東京大学大学院理学系研究科物理学専攻(2016)。
[55] F. Sekiguchi, T. Mochizuki, C. Kim, H. Akiyama, L. N. Pfeiffer, K. W. West, and R. Shimano, “Anomalous Metal Phase Emergent on the Verge of an Exciton Mott Transition,” Phys. Rev. Lett. 118, 067401 (2017).
[56] C. Comte and G. Mahler, “Dynamic Stark effect in interacting electron-hole systems: Light- enhanced excitons,” Phys. Rev. B 34, 7164 (1986).
[57] C. Comte and G. Mahler, “Excitonic reference state of a model semiconductor in the dynamic Stark regime,” Phys. Rev. B 38, 10517 (1988).
[58] S. Glutsch and R. Zimmermann, “Coherent optics for pumping near the absorption edge,” Phys. Rev. B 45, 5857 (1992).
[59] T. Iida, Y. Hasegawa, H. Higashimura, M. Aihara, “Density bistability in an interacting electron- hole system in coherently excited semiconductors,” Phys. Rev. B 47, 9328 (1993).
[60] T. J. Inagaki, T. Iida, and M. Aihara, “Many-body theory of pump-probe spectra for highly excited semiconductors,” Phys. Rev. B 62, 10852 (2000).
[61] Th. O¨ streich and K. Sch¨onhammer, “Non-stationary excitonic-insulator states in photoexcited semiconductors,” Z. Phys. B 91, 189 (1993).
[62] K. Hannewald, S. Glutsch, and F. Bechstedt, “Excitonic insulator through coherent pulse excita- tion?” J. Phys.: Condens. Matter 13, 275 (2001).
[63] A. Mysyrowicz, D. Hulin, A. Antonetti, A. Migus, W. T. Masselink, and H. Morko¸c, “‘Dressed Excitons’ in a Multiple-Quantum-Well Structure: Evidence for an Optical Stark Effect with Fem- tosecond Response Time,” Phys. Rev. Lett. 56, 2748 (1986).
[64] S. Schmitt-Rink and D. S. Chemla, “Collective Excitations and the Dynamical Stark Effect in a Coherently Driven Exciton System,” Phys. Rev. Lett. 57, 2752 (1986).
[65] S. Schmitt-Rink, D. S. Chemla, and H. Haug, “Nonequilibrium theory of the optical Stark effect and spectral hole burning in semiconductors,” Phys. Rev. B 37, 941 (1988).
[66] M. Combescot and R. Combescot, “Excitonic Stark Shift: A Coupling to ‘Semivirtual’ Biexcitons,” Phys. Rev. Lett. 61, 117 (1988).
[67] D. S. Chemla, W. H. Knox, D. A. B. Miller, S. Schmitt-Rink, J. B. Stark, R. Zimmermann, “The Excitonic Optical Stark Effect in Semiconductor Quantum Wells Probed with Femtosecond Optical Pulses,” J. Lumin. 44, 233 (1989).
[68] R. Shimano and M. Kuwata-Gonokami, “Observation of Autler-Townes splitting of biexcitons in CuCl,” Phys. Rev. Lett. 72, 530 (1994).
[69] C. Ciuti, C. Piermarocchi, V. Savona, P. E. Selbmann, P. Schwendimann, and A. Quattropani, “Strongly Driven Exciton Resonances in Quantum Wells: Light-Induced Dressing versus Coulomb Scattering,” Phys. Rev. Lett. 84, 1752 (2000).
[70] M. Saba, F. Quochi, C. Ciuti, D. Martin, J.-L. Staehli, B. Deveaud, A. Mura, and G. Bongiovanni, “Direct observation of the excitonic ac Stark splitting in a quantum well,” Phys. Rev. B 62, R16322 (2000).
[71] M. Phillips and H. Wang, “Spin Coherence and Electromagnetically Induced Transparency via Exciton Correlations,” Phys. Rev. Lett. 89, 186401 (2002).
[72] M. C. Phillips and H. Wang, “Exciton spin coherence and electromagnetically induced trans- parency in the transient optical reponse of GaAs quantum wells,” Phys. Rev. B 69, 115337 (2004).
[73] H. Haug and S. W. Koch, Quantum Theory of the Optical and Electronic Properties of Semicon- ductors, World Scientific, Fifth Edition (2009).
[74] G. Grosso and G. P. Parravicini, Solid State Physics, Academic Press, Second Edition (2014).
[75] R. J. Elliott, “Intensity of Optical Absorption by Excitons,” Phys. Rev. 108, 1384 (1957).
[76] D. D. Sell, “Resolved Free-Exciton Transitions in the Optical-Absorption Spectrum of GaAs,” Phys. Rev. B 6, 3750 (1972).
[77] D. W. Snoke and J. D. Crawford, “Hysterisis in the Mott transition between plasma and insulating gas,” Phys. Rev. E 52, 5796 (1995).
[78] S. Arndt, W. D. Kraeft, and J. Seide, “Two-Particle Energy Spectrum in Dense Electron-Hole Plasmas,” Phys. Stat. Sol. B 194, 601 (1996)
[79] S. W. Koch, W. Hoyer, M. Kira, and V. S. Filinov, “Exciton ionization in semiconductors,” Phys. Stat. Sol. B 238, 404 (2003).
[80] D. Semkat, F. Richter, D. Kremp, G. Manzke, W.-D. Kraeft, and K. Henneberger, “Ionization equilibrium in an excited semiconductor: Mott transition versus Bose-Einstein condensation,” Phys. Rev. B 80, 155201 (2009).
[81] T. Yoshioka and K. Asano, “Exciton-Mott Physics in a Quasi-One-Dimensional Electron-Hole System,” Phys. Rev. Lett. 107, 256403 (2011).
[82] G Manzke, D Semkat, and H Stolz, “Mott transition of excitons in GaAs-GaAlAs quantum wells,” New J. Phys. 14, 095002 (2012).
[83] T. Yoshioka and K. Asano, “Classical-quantum crossovers in quasi-one-dimensional electron-hole systems: Exciton-Mott physics and interband optical spectra,” Phys. Rev. B 86, 115314 (2012).
[84] K. Asano and T. Yoshioka, “Exciton-Mott Physics in Two-Dimensional Electron-Hole Systems: Phase Diagram and Single-Particle Spectra,” J. Phys. Soc. Jpn. 83, 084702 (2014).
[85] H. Haug and S. Schmitt-Rink, “Electron Theory of the Optical Properties of Laser-Excited Semi- conductors,” Prog. Quantum Electron. 9, 3 (1984).
[86] R. Zimmermann, “Excitons and Electron-Hole Plasma. A Ground State Calculation,” Phys. Stat. Sol. B 76, 191 (1976).
[87] L. V. Keldysh, “Coherent states of excitons,” Physics Uspekhi 60, 1180 (2017).
[88] Q. Chen, J. Stajic, S. Tan, and K. Levin, “BCS-BEC crossover: From high temperature super- conductors to ultracold superfluids,” Phys. Rep. 412, 1 (2005).
[89] T. Ogawa, Y. Tomio, and K. Asano, “Quantum condensation in electron-hole systems: excitonic BEC-BCS crossover and biexciton,” J. Phys.: Condens. Matter 19, 295205 (2007). crystallization
[90] V. M. Galitskiˇı, S. P. Goreslavskiˇı, and V. F. Elesin, Zh. Eksp. Teor. Fiz. 57, 207 (1969) [“Electric and Magnetic Properties of a Semiconductor in the Field of a Strong Electromagnetic Wave,” Sov. Phys. JETP 30, 117 (1970)].
[91] L. V. Keldysh, “Correlations in the Coherent Transient Electron-Hole System,” Phys. Stat. Sol. B 188, 11 (1995).
[92] C. A. R. Sa de Melo, M. Randeria, and J. R. Engelbrecht, “Crossover from BCS to Bose Supercon- ductivity: Transition Temperature and Time-Dependent Ginzburg-Landau Theory,” Phys. Rev. Lett. 71, 3202 (1993).
[93] M. Randeria, “Pre-pairing for condensation,” Nat. Phys. 6, 561 (2010).
[94] S. Tsuchiya, R. Watanabe, and Y. Ohashi, “Single-particle properties and pseudogap effects in the BCS-BEC crossover regime of an ultracoled Fermi gas above Tc,” Phys. Rev. A 80, 033613 (2009).
[95] R. Watanabe, S. Tsuchiya, and Y. Ohashi, “Superfluid density of states and pseudogap phe- nomenon in the BCS-BEC crossover regime of a superfluid Fermi gas,” Phys. Rev. A 82, 043630 (2010).
[96] D. Kremp, D. Semkat, and K. Henneberger, “Quantum condensation in electron-hole plasmas,” Phys. Rev. B 78, 125315 (2008).
[97] G. Mazza and A. Georges, “Superradiant Quantum Materials,” Phys. Rev. Lett. 122, 017401 (2019).
[98] M. A. M. Versteegh, A. J. van Lange, H. T. C. Stoof, and J. I. Dijkhuis, “Observation of preformed electron-hole Cooper pairs in highly excited ZnO,” Phys. Rev. B 85, 195206 (2012).
[99] H. Chu and Y. C. Chang, “Theory of optical spectra of exciton condensates,” Phys. Rev. B 54, 5020 (1996).
[100] H. Chu and Y. C. Chang, “Optical spectra of exciton condensates in semiconductor quantum wells,” Europhys. Lett. 35, 535 (1996).
[101] Y. Nambu, “Quasi-particles and gauge invariance in the theory of superconductivity,” Phys. Rev. 117, 648 (1960).
[102] J. Goldstone, “Field theories with ‘superconductor’ solutions,” Nuovo Cimento 19, 154 (1961).
[103] J. Goldstone, A. Salam, and S. Weinberg, “Broken symmetries,” Phys. Rev. 127, 965 (1962).
[104] R. Cˆot´e and A. Griffin, “Excitonic modes in a Bose-condensed electron-hole gas in the pairing approximation,” Phys. Rev. B 37, 4539 (1988).
[105] Z. Koinov, “Direct optical transitions in semiconductors in the presence of the exciton condensed phase,” Phys. Rev. B 72, 085203 (2005).
[106] Z. G. Koinov, M. Fortes, M. de Llano, and M. A. Sol´ıs, “Unified description of collective modes in superconductors and semiconductors with an exciton condensed phase,” Phys. Stat. Sol. B 247, 2207 (2010).
[107] R. Matsunaga, Y. I. Hamada, K. Makise, Y. Uzawa, H. Terai, Z. Wang, and R. Shimano, “Higgs Amplitude Mode in the BCS Superconductors Nb1−xTixN Induced by Terahertz Pulse Excitation,” Phys. Rev. Lett. 111, 057002 (2013).
[108] R. Matsunaga, N. Tsuji, H. Fujita, A. Sugioka, K. Makise, Y. Uzawa, H. Terai, Z. Wang, H. Aoki, and R. Shimano, “Light-induced collective pseudospin precession resonating with Higgs mode in a superconductor,” Science 345, 1145 (2014).
[109] R. Matsunaga and R. Shimano, “Nonlinear terahertz spectroscopy of Higgs mode in s-wave super- conductors,” Phys. Scr. 92, 024003 (2017).
[110] K. Katsumi, N. Tsuji, Y. I. Hamada, R. Matsunaga, J. Schneeloch, R. D. Zhong, G. D. Gu, H. Aoki, Y. Gallais, and R. Shimano, “Higgs Mode in the d-Wave Superconductor Bi2Sr2CaCu2O8+x Driven by an Intense Terahertz Pulse,” Phys. Rev. Lett. 120, 117001 (2018).
[111] Y. T. H. Le and T. J. Inagaki, “Density dependence of the terahertz absorption spectra in optically excited semiconductors,” Phys. Stat. Sol. B 252, 589 (2015).
[112] M. Combescot, O. Betbeder-Matibet, and R. Combescot, “Bose-Einstein Condensation in Semi- conductors: The Key Role of Dark Excitons,” Phys. Rev. Lett. 99, 176403 (2007).
[113] R. Combescot and M. Combescot, “‘Gray’ BCS Condensate of Excitons and Internal Josephson Effect,” Phys. Rev. Lett. 109, 026401 (2012).
[114] W. D. Kraeft, D. Kremp, W. Ebeling, and G. R¨opke, Quantum Statistics of Charged Particle Systems, Springer (1986).
[115] M. Lindberg and S. W. Koch, “Effective Bloch equations for semiconductors,” Phys. Rev. B 38, 3342 (1988).
[116] H. Haug and S. W. Koch, “Semiconductor laser theory with many-body effects,” Phys. Rev. A 39, 1887 (1989).
[117] C. Ell, H. Haug, and S. W. Koch, “Many-body effects in gain and refractive-index spectra of bulk and quantum-well semiconductor lasers,” Opt. Lett. 14, 356 (1989).
[118] C. Ell, R. Blank, S. Benner, and H. Haug, “Simplified calculations of the optical spectra of two-and three-dimensional laser-excited semiconductors,” J. Opt. Soc. Am. B 6, 2006 (1989).
[119] V. M. Axt and A. Stahl, “A dynamics-controlled truncation scheme for the hierarchy of density matrices in semiconductor optics,” Z. Phys. B 93, 195 (1994).
[120] V. M. Axt and A. Stahl, “The role of the biexciton in a dynamic density matrix theory of the semiconductor band edge,” Z. Phys. B 93, 205 (1994).
[121] I. Balslev and E. Hanamura, “The role of biexcitons in induced absorption and the dynamical Stark effect,” Solid State Commun. 72, 843 (1989).
[122] W. Sch¨afer, D. S. Kim, J. Shah, T. C. Damen, J. E. Cunningham, K. W. Goossen, L. N. Pfeiffer, and K. K¨ohler, “Femtosecond coherent fields induced by many-particle correlations in transient four-wave mixing,” Phys. Rev. B 53, 16429 (1996).
[123] C. Sieh, T. Meier, A. Knorr, F. Jahnke, P. Thomas, and S. W. Koch, “Influence of carrier correla- tions on the excitonic optical response including disorder and microcavity effects,” Eur. Phys. J. B 11, 407 (1999).
[124] M. Kuwata-Gonokami, S. Inouye, H. Suzuura, M. Shirane, R. Shimano, T. Someya, and H. Sakaki, “Parametric Scattering of Cavity Polaritons,” Phys. Rev. Lett. 79, 1341 (1997).
[125] H. Suzuura, Yu. P. Svirko, and M. Kuwata-Gonokami, “Four-wave mixing theory in a cavity- polariton system,” Solid State Commun. 108, 289 (1998).
[126] M. Shirane, C. Ramkumar, Yu. P. Svirko, H. Suzuura, S. Inouye, R. Shimano, T. Someya, H. Sakaki, and M. Kuwata-Gonokami, “Degenerate four-wave mixing measurements on an exciton- photon coupled system in a semiconductor microcavity,” Phys. Rev. B 58, 7978 (1998).
[127] Yu. P. Svirko, M. Shirane, H. Suzuura, M. Kuwata-Gonokami, “Four-Wave Mixing Theory at the Excitonic Resonance: Weakly Interacting Boson Model,” J. Phys. Soc. Jpn. 68, 674 (1999).
[128] M. Kuwata-Gonokami, T. Aoki, C. Ramkumar, R. Shimano, and Yu. P. Svirko, “Role of exciton- exciton interaction on resonant third-order nonlinear optical response,” J. Lumin. 87-89, 162 (2000).
[129] T. Usui, “Excitations in a High Density Electron Gas. I,” Prog. Theor. Phys. 23, 787 (1960).
[130] E. Hanamura, “Theory of the High Density Exciton. I,” J. Phys. Soc. Jpn. 29, 50 (1970).
[131] E. Hanamura, “Theory of Many Wannier Excitons. I,” J. Phys. Soc. Jpn. 37, 1545 (1974).
[132] E. Hanamura, “Theory of Many Wannier Excitons. II. Absence of Self-Induced Transparency,” J. Phys. Soc. Jpn. 37, 1553 (1974).
[133] T. Hiroshima, “Nonresonant excitonic optical nonlinearity in semiconductors,” Phys. Rev. B 40, 3862 (1989).
[134] J. Inoue, T. Brandes, and A. Shimizu, “Effective Hamiltonian for Excitons with Spin Degrees of Freedom,” J. Phys. Soc. Jpn. 67, 3384 (1998).
[135] A. Thilagam, “Exciton-exciton interaction in semiconductor quantum wells,” Phys. Rev. B 63, 045321 (2001).
[136] S. Okumura and T. Ogawa, “Boson representation of two-exciton correlations: An exact treatment of composite-particle effects,” Phys. Rev. B 65, 035105 (2001).
[137] 島野亮、「励起子系の超高速コヒーレント非線形光学応答の研究」、博士学位論文、東京大学大学院工学系研究科物理工学専攻(2000)。
[138] 青木隆朗、「半導体における励起子間相互作用と非線形光学応答の研究」、博士学位論文、東京大学大学院工学系研究科物理工学専攻(2001)。
[139] Th. O¨ streich, K. Sch¨onhammer, L. J. Sham, “Theory of exciton-exciton correlation in nonlinear optical response,” Phys. Rev. B 58, 12920 (1998).
[140] L. B´anyai, D. B. Tran Thoai, E. Reitsamer, H. Haug, D. Steinbach, M. U. Wehner, M. Wegener, T. Marschner, and W. Stolz, “Exciton-LO-Phonon Quantum Kinetics: Evidence of Memory Effects in Bulk GaAs,” Phys. Rev. Lett. 75, 2188 (1995).
[141] H. Haug and A. P. Jauho, Quantum Kinetics in Transport and Optics of Semiconductors, Springer (1996).
[142] Q. T. Vu and H. Haug, “Detection of light-induced band gaps by ultrafast femtosecond pump and probe spectroscopy,” Phys. Rev. B 71, 035305 (2005).
[143] M. Lindberg, R. Binder, and S. W. Koch, “Theory of the semiconductor photon echo,” Phys. Rev. A 45, 1865 (1992).
[144] J. R. Chelikowsky and M. L. Cohen, “Nonlocal pseudopotential calculations for the electronic structure of eleven diamond and zinc-blend semiconductors,” Phys. Rev. B 14, 556 (1976).
[145] P. Lautenschlager, M. Garriga, S. Logothetidis, and M. Cardona, “Interband critical points of GaAs and their temperature dependence,” Phys. Rev. B 35, 9174 (1987).
[146] M. Kozhevnikov, B. M. Ashkinadze, E. Cohen, and A. Ron, “Low-temperature electron mobility studied by cyclotron resonance in ultrapure GaAs crystals,” Phys. Rev. B 52, 17165 (1995).
[147] G. Dresselhaus, A. F. Kip, and C. Kittel, “Cyclotron Resonance of Electrons and Holes in Silicon and Germanium Crystals,” Phys. Rev. 98, 368 (1955).
[148] M. S. Skolnick, A. K. Jain, R. A. Stradling, J. Leotin, J. C. Ousset, and S. Askenazy, “An investigation of the anisotropy of the valence band of GaAs by cyclotron resonance,” J. Phys. C: Solid State Phys. 9, 2809 (1976).
[149] S. Adachi, GaAs and Related Materials: Bulk Semiconducting and Superlattice Properties, World Scientific (1994).
[150] A. Baldereschi and N. O. Lipari, “Direct Exciton Spectrum in Diamond and Zinc-Blende Semi- conductors,” Phys. Rev. Lett. 25, 373 (1970).
[151] A. Baldereschi and N. O. Lipari, “Energy Levels of Direct Excitons in Semiconductors with De- generate Bands,” Phys. Rev. B 3, 439 (1971).
[152] G. W. Fehrenbach, W. Sch¨afer, J. Treusch, and R. G. Ulbrich, “Transient Optical Spectra of a Dense Exciton Gas in a Direct-Gap Semiconductor,” Phys. Rev. Lett. 49, 1281 (1982).
[153] 中山正昭著、「半導体の光物性」、コロナ社(2013)。
[154] R. G. Ulbrich and C. Weisbuch, “Resonant Brillouin Scattering of Excitonic Polaritons in Gallium Arsenide,” Phys. Rev. Lett. 38, 865 (1977).
[155] A. Tredicucci, Y. Chen, F. Bassani, J. Massies, C. Deparis, and G. Neu, “Center-of-mass quanti- zation of excitons and polariton interference in GaAs thin layers,” Phys. Rev. B 47, 10348 (1993).
[156] A. C. Schaefer and D. G. Steel, “Nonlinear Optical Response of the GaAs Exciton Polariton,” Phys. Rev. Lett. 79, 4870 (1997).
[157] 高山正行、「半導体 GaAs 中に共鳴励起された励起子系の励起子間相互作用と緩和ダイナミクスの研究」、博士学位論文、東京大学大学院理学系研究科物理学専攻(2019)。
[158] I. Pelant and J. Valenta, Luminescence Spectroscopy of Semiconductors, Oxford University Press (2012).
[159] B. L. Wilmer, D. Webber, J. M. Ashley, K. C. Hall, and A. D. Bristow, “Role of strain on the coherent properties of GaAs excitons and biexcitons,” Phys. Rev. B 94, 075207 (2016).
[160] M. Jiang, A. C. Schaefer, and D. G. Steel, “Polarization dependence of the frequency-domain four-wave mixing response of excitons in GaAs,” Phys. Rev. B 51, 16714 (1995).
[161] Y. Murotani, M. Takayama, F. Sekiguchi, C. Kim, H. Akiyama, and R. Shimano, “Terahertz field-induced ionization and perturbed free induction decay of excitons in bulk GaAs,” J. Phys. D: Appl. Phys. 51, 114001 (2018).
[162] R. W. Boyd, Nonlinear Optics, Academic Press, Third Edition (2008).
[163] A. Ghalgaoui, K. Reimann, M. Woerner, T. Elsaesser, C. Flytzanis, and K. Biermann, “Resonant Second-Order Nonlinear Terahertz Response of Gallium Arsenide,” Phys. Rev. Lett. 121 266602 (2018).
[164] J. Shah, Ultrafast Spectroscopy of Semiconductors and Semiconductor Nanostructures, Springer, Second Enlarged Edition (1999).
[165] M. Yoshizawa and M. Kurosawa, “Femtosecond time-resolved Raman spectroscopy using stimu- lated Raman scattering,” Phys. Rev. A 61, 013808 (1999).
[166] D. W. McCamant, P. Kukura, and R. A. Mathies, “Femtosecond Time-Resolved Stimulated Ra- man Spectroscopy: Application to the Ultrafast Internal Conversion in β-Carotene,” J. Phys. Chem. A 107, 8208 (2003).
[167] D. W. McCamant, P. Kukura, S. Yoon, and R. A. Mathies, “Femtosecond broadband stimulated Raman spectroscopy: Apparatus and methods,” Rev. Sci. Instrum. 75, 4971 (2004).
[168] G. Batignani, D. Bossini, N. Di Palo, C. Ferrante, E. Pontecorvo, G. Cerullo, A. Kimel, and T. Scopigno, “Probing ultrafast photo-induced dynamics of the exchange energy in a Heisenberg antiferromagnet,” Nat. Photon. 9, 506 (2015).
[169] Z. Zhang, F. Wen, J. Che, D. Zhang, C. Li, Y. Zhang, and M. Xiao, “Dressed Gain from the Parametrically Amplified Four-Wave Mixing Process in an Atomic Vapor,” Sci. Rep. 5, 15058 (2015).
[170] M. C. Beard, G. M. Turner, C. A. Schmuttenmaer, “Transient photoconductivity in GaAs as measured by time-resolved terahertz spectroscopy,” Phys. Rev. B 62, 15764 (2000).
[171] R. Huber, F. Tauser, A. Brodschelm, M. Bichler, G. Abstreiter, and A. Leitenstorfer, “How many- particle interactions develop after ultrafast excitation of an electron-hole plasma,” Nature 414, 286 (2001).
[172] R. A. Kaindl, M. A. Carnahan, D. H¨agele, R. L¨ovenich, and D. S. Chemla, “Ultrafast terahertz probes of transient conducting and insulating phases in an electron-hole gas,” Nature 423, 734 (2003).
[173] R. Huber, R. A. Kaindl, B. A. Schmid, D. S. Chemla, “Broadband terahertz study of excitonic resonances in the high-density regime in GaAs/AlxGa1−xAs quantum wells,” Phys. Rev. B 72, 161314(R) (2005).
[174] R. A. Kaindl, D. H¨agele, M. A. Carnahan, and D. S. Chemla, “Transient terahertz spectroscopy of excitons and unbound carriers in quasi-two-dimensional electron-hole gases,” Phys. Rev. B 79, 045320 (2009).
[175] T. Suzuki and R. Shimano, “Time-Resolved Formation of Excitons and Electron-Hole Droplets in Si Studied Using Terahertz Spectroscopy,” Phys. Rev. Lett. 103, 057401 (2009).
[176] T. Suzuki and R. Shimano, “Cooling dynamics of photoexcited carriers in Si studied using optical pump and terahertz probe spectroscopy,” Phys. Rev. B 83, 085207 (2011).
[177] R. Ulbricht, E. Hendry, J. Shan, T. F. Heinz, and M. Bonn, “Carrier dynamics in semiconductors studied with time-resolved terahertz spectroscopy,” Rev. Mod. Phys. 83, 543 (2011).
[178] Q. Zhang, Y. Wang, W. Gao, Z. Long, J. D. Watson, M. J. Manfra, A. Belyanin, and J. Kono, “Stability of High-Density Two-Dimensional Excitons against a Mott Transition in High Magnetic Fields Probed by Coherent Terahertz Spectroscopy,” Phys. Rev. Lett. 117, 207402 (2016).
[179] 服部利明著、「非線形光学入門」、裳華房(2009)。
[180] 大野木哲也、田中耕一郎著、「電磁気学 II」、東京図書(2017)。
[181] Yu. Berozashvili, S. Machavariani, A. Natsvlishvili, and A. Chirakadze, “Dispersion of the linear electro-optic coefficients and the non-linear susceptibility in GaP,” J. Phys. D: Appl. Phys. 22, 682 (1989).
[182] J. Hebling, A. G. Stepanov, G. Alm´asi, B. Bartal, and J. Kuhl, “Tunable THz pulse generation by optical rectification of ultrashort laser pulses with tilted pulse fronts,” Appl. Phys. B
[183] 室谷悠太、「過渡吸収分光による GaAs 中に光励起された低温電子正孔系の研究」、修士学位論文、東京大学大学院理学系研究科物理学専攻(2017)。
[184] Y. Murotani, C. Kim, H. Akiyama, L. N. Pfeiffer, K. W. West, and R. Shimano, “Light-Driven Electron-Hole Bardeen-Cooper-Schrieffer-Like State in Bulk GaAs,” Phys. Rev. Lett. 123, 197401 (2019).
[185] Y. R. Shen, The Principles of Nonlinear Optics, John Wiley & Sons (2003).
[186] C. Sieh, T. Meier, F. Jahnke, A. Knorr, S. W. Koch, P. Brick, M. Hu¨bner, C. Ell, J. Prineas, G. Khitrova, and H. M. Gibbs, “Coulomb Memory Signatures in the Excitonic Optical Stark Effect,” Phys. Rev. Lett. 82, 3112 (1999).
[187] T. Meier, S. W. Koch, M. Phillips, and H. Wang, “Strong coupling of heavy- and light-hole excitons induced by many-body correlations,” Phys. Rev. B 62, 12605 (2000).
[188] T. Ostatnicky´, O. Cr´egut, M. Gallart, P. Gilliot, B. H¨onerlage, J.-P. Likforman, “Electron- and hole-spin relaxation within excitons in GaAs quantum wells by non-degenerate pump-and-probe measurements,” Phys. Rev. B 75, 165311 (2007).
[189] E. Burstein, “Anomalous Optical Absorption Limit in InSb,” Phys. Rev. 93, 632 (1954).
[190] T. S. Moss, “The Interpretation of the Properties of Indium Antimonide,” Proc. Phys. Soc. B 67, 775 (1954).
[191] G. D. Mahan, “Excitons in Degenerate Semiconductors,” Phys. Rev. 153, 882 (1967).
[192] G. W. ‘t Hooft, W. A. J. A. van der Poel, L. W. Molenkamp, and C. T. Foxon, “Giant oscillator strength of free excitons in GaAs,” Phys. Rev. B 35, 8281 (1987).
[193] J. Shah, R. F. Leheny, and W. Wiegmann, “Low-temperature absorption spectrum in GaAs in the presence of optical pumping,” Phys. Rev. B 16, 1577 (1977).
[194] C. V. Shank, R. L. Fork, R. F. Leheny, and J. Shah, “Dynamics of Photoexcited GaAs Band-Edge Absorption with Subpicosecond Resolution,” Phys. Rev. Lett. 42, 112 (1979).
[195] K. L. Shaklee and R. F. Leheny, “Direct Determination of Optical Gain in Semiconductor Crys- tals,” Appl. Phys. Lett. 18, 475 (1971).
[196] K. L. Shaklee, R. F. Leheny, and R. E. Nahory, “Optical Gain in Lightly Doped GaAs,” Appl. Phys. Lett. 19, 302 (1971).
[197] O. Hildebrand, B. O. Faltermeier, and M. H. Pilkuhn, “Direct Determination of Reduced Band Gap and Chemical Potential in an Electron-Hole Plasma in High-Purity GaAs,” Solid State Commun. 19, 841 (1976).
[198] R. Zimmermann, “Final State Interactions in the Gain and Absorption Spectra of Electron-Hole Liquids,” Phys. Stat. Sol. B 86, K63 (1978).
[199] H. Haug and D. B. Tran Thoai, “Gain Spectrum of an e-h Liquid in Direct Gap Semiconductors,” Phys. Stat. Sol. B 98, 581 (1980).
[200] S. Schmitt-Rink, J. L¨owenau, and H. Haug, “Theory of Absorption and Refraction of Direct-Gap Semiconductors with Arbitrary Free-Carrier Concentrations,” Z. Phys. B 47, 13 (1982).
[201] J. P. L¨owenau, S. Schmitt-Rink, and H. Haug, “Many-Body Theory of Optical Bistability in Semiconductors,” Phys. Rev. Lett. 49, 1511 (1982).
[202] W. Sch¨afer, R. Binder, and K. H. Schuldt, “The Influence of Dynamical Correlations in Semicon- ductor Plasmas on Optical Spectra,” Z. Phys. B 70, 145 (1988).
[203] N. H. Kwong, G. Rupper, and R. Binder, “Self-consistent T-matrix theory of semiconductor light- absorption and luminescence,” Phys. Rev. B 79, 155205 (2009).
[204] M. D. Sturge, “Optical Absorption of Gallium Arsenide between 0.6 and 2.75 eV,” Phys. Rev. 127, 768 (1962).
[205] R. Binder, S. W. Koch, M. Lindberg, N. Peyghambarian, and W. Sch¨afer, “Ultrafast Adiabatic Following in Semiconductors,” Phys. Rev. Lett. 65, 899 (1990).
[206] A. Schu¨lzgen, R. Binder, M. E. Donovan, M. Lindberg, K. Wundke, H. M. Gibbs, G. Khitrova, and N. Peyghambarian, “Direct Observation of Excitonic Rabi Oscillations in Semiconductors,” Phys. Rev. Lett. 82, 2346 (1999).
[207] R. L¨ovenich, C. W. Lai, D. H¨agele, D. S. Chemla, and W. Sch¨afer, “Semiconductor polarization dynamics from the coherent to the incoherent regime: Theody and experiment,” Phys. Rev. B 66, 045306 (2002).
[208] B. Pal and A. S. Vengurlekar, “Excitonic polarization dephasing under strong resonant pulsed excitation in GaAs quantum wells,” Phys. Rev. B 66, 155337 (2002).
[209] M. Kira and S. W. Koch, “Many-body correlations and excitonic effects in semiconductor spec- troscopy,” Prog. Quantum Electron. 30, 155 (2006).
[210] T. J. Inagaki and M. Aihara, “Many-body theory for luminescence spectra in high-density electron- hole systems,” Phys. Rev. B 65, 205204 (2002).
[211] E. Perfetto, D. Sangalli, A. Marini, and G. Stefanucci, “First-principles approach to excitons in time-resolved and angle-resolved photoemission spectra,” Phys. Rev. B 94, 245303 (2016).
[212] A. Steinhoff, M. Florian, M. R¨osner, G. Sch¨onhoff, T. O. Wehling, and F. Jahnke, “Exciton fission in monolayer transition metal dichalcogenide semiconductors,” Nat. Commun. 8, 1166 (2017).
[213] A. Rustagi and A. F. Kemper, “Photoemission signature of excitons,” Phys. Rev. B 97, 235310 (2018).
[214] A. Rustagi and A. F. Kemper, “Coherent excitonic quantum beats in time-resolved photoemission measurements,” Phys. Rev. B 99, 125303 (2019).
[215] D. Christiansen, M. Selig, E. Malic, R. Ernstorfer, and A. Knorr, “Theory of exciton dynamics in time-resolved ARPES: Intra- and intervalley scattering in two-dimensional semiconductors,” Phys. Rev. B 100, 205401 (2019).
[216] D. Ihle, M. Pfafferott, E. Burovski, F. X. Bronold, and H. Fehske, “Bound state formation and the nature of the excitonic insulator phase in the extended Falicov-Kimball model,” Phys. Rev. B 78, 193103 (2008).
[217] E. Perfetto, D. Sangalli, A. Marini, and G. Stefanucci, “Pump driven normal-to-excitonic insulator transition: Josephson oscillations and signatures of BEC-BCS crossover in time-resolved ARPES,” Phys. Rev. Materials 3, 124601 (2019).
[218] J. Kanasaki, H. Tanimura, and K. Tanimura, “Imaging Energy-, Momentum-, and Time-Resolved Distributions of Photoinjected Hot Electrons in GaAs,” Phys. Rev. Lett. 113, 237401 (2014).
[219] H. Tanimura, J. Kanasaki, K. Tanimura, J. Sjakste, N. Vast, M. Calandra, and F. Mauri, “For- mation of hot-electron ensembles quasiequilibrated in momentum space by ultrafast momentum scattering of highly excited hot electrons photoinjected into the Γ valley of GaAs,” Phys. Rev. B 93, 161203(R) (2016).
[220] 松井宏樹、嵐田雄介、平野大輔、森田悠介、大間知潤子、O. E. Tereshchenko、吉岡孝高、湯本潤司、五神真、「角度分解光電子分光による半導体 GaSe の光励起状態の観測」、日本物理学会第 73 回年次大会、 23aK503-10、東京理科大学(2018)。
[221] K. Dani, “Time-resolved Photoemission Spectroscopies of Semiconductor Systems,” Fundamental Optical Processes in Semiconductors 2019, Tu3.3, Banff (2019).
[222] R. G. Ulbrich and G. W. Fehrenbach, “Polariton Wave Packet Propagation in the Exciton Reso- nance of a Semiconductor,” Phys. Rev. Lett. 43, 963 (1979).
[223] Y. Segawa, Y. Aoyagi, and S. Namba, “Anomalously slow group velocity of upper branch polariton in CuCl,” Solid State Commun. 32, 229 (1979).
[224] T. Itoh, P. Lavallard, J. Reydellet, C. Benoit `a la Guillaume, “Time of flight of excitonic polaritons in CdSe,” Solid State Commun. 37, 925 (1981).
[225] J.-C. Diels and W. Rudolph, Ultrafast Laser Pulse Phenomena, Academic Press, Second Edition (2006).
[226] J.-P. Likforman, M. Joffre, and D. Hulin, “Hyper-Raman Gain due to Excitons Coherently Driven with Femtosecond Pulses,” Phys. Rev. Lett. 79, 3716 (1997).
[227] J. J. Hopfield, “Theory of the Contribution of Excitons to the Complex Dielectric Constant of Crystals,” Phys. Rev. 112, 1555 (1958).
[228] L. Schultheis, J. Kuhl, A. Honold, and C. W. Tu, “Ultrafast Phase Relaxation of Excitons via Exciton-Exciton and Exciton-Electron Collisions,” Phys. Rev. Lett. 57, 1635 (1986).
[229] L. Schultheis, J. Kuhl, A. Honold, and C. W. Tu, “Picosecond Phase Coherence and Orientational Relaxation of Excitons in GaAs,” Phys. Rev. Lett. 57, 1797 (1986).
[230] M. O¨ . Oktel and L. S. Levitov, “Optical Excitations in a Nonideal Bose Gas,” Phys. Rev. Lett. 83, 6 (1999).
[231] K. Johnsen and G. M. Kavoulakis, “Probing Bose-Einstein Condensation of Excitons with Elec- tromagnetic Radiation,” Phys. Rev. Lett. 86, 858 (2001).
[232] J. Orenstein and J. S. Dodge, “Terahertz time-domain spectroscopy of transient metallic and superconducting states,” Phys. Rev. B 92, 134507 (2015).
[233] T. J. Inagaki and M. Aihara, “Infrared absorption in high-density electron-hole systems: The role of quantum fluctuations,” Phys. Rev. B 66, 075204 (2002).
[234] D. Dunn, “Optical absorption by excitons: II,” J. Phys. C: Solid State Phys. 10, 2801 (1977).
[235] S. Glutsch, D. S. Chemla, and F. Bechstedt, “Numerical calculation of the optical absorption in semiconductor quantum structures,” Phys. Rev. B 54, 11592 (1996).
[236] P. Coleman, Introduction to Many-Body Physics, Cambridge University Press (2015).