Laser spectroscopic probing of coexisting superfluid and insulating states of an atomic Bose-Hubbard system

Shinya Kato; Kensuke Inaba; Seiji Sugawa; Kosuke Shibata; Ryuta Yamamoto; Makoto Yamashita; Yoshiro Takahashi

doi:10.1038/ncomms11341

Laser spectroscopic probing of coexisting superfluid and insulating states of an atomic Bose-Hubbard system

Shinya Kato^*, Kensuke Inaba, Seiji Sugawa, Kosuke Shibata, Ryuta Yamamoto, Makoto Yamashita, Yoshiro Takahashi

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

18 Citations (Scopus)

Abstract

A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose-Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.

Original language	English
Article number	11341
Journal	Nature communications
Volume	7
DOIs	https://doi.org/10.1038/ncomms11341
Publication status	Published - 2016 Apr 20
Externally published	Yes

ASJC Scopus subject areas

Chemistry(all)
Biochemistry, Genetics and Molecular Biology(all)
Physics and Astronomy(all)

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10.1038/ncomms11341

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title = "Laser spectroscopic probing of coexisting superfluid and insulating states of an atomic Bose-Hubbard system",

abstract = "A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose-Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.",

author = "Shinya Kato and Kensuke Inaba and Seiji Sugawa and Kosuke Shibata and Ryuta Yamamoto and Makoto Yamashita and Yoshiro Takahashi",

note = "Funding Information: We thank Y. Nakamura for valuable discussions. This work is supported by Grants-in-Aid for Scientific Research of JSPS (Nos. 18204035, 21102005C01 (Quantum Cybernetics), 22684022, 14J02311, 25220711, and 26247064), the GCOE Program The Next Generation of Physics, Spun from Universality and Emergence from MEXT of Japan, FIRST program, JST CREST, and the Impulsing Paradigm Change through Disruptive Technologies (ImPACT) program.",

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doi = "10.1038/ncomms11341",

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AU - Kato, Shinya

AU - Inaba, Kensuke

AU - Sugawa, Seiji

AU - Shibata, Kosuke

AU - Yamamoto, Ryuta

AU - Yamashita, Makoto

AU - Takahashi, Yoshiro

N1 - Funding Information: We thank Y. Nakamura for valuable discussions. This work is supported by Grants-in-Aid for Scientific Research of JSPS (Nos. 18204035, 21102005C01 (Quantum Cybernetics), 22684022, 14J02311, 25220711, and 26247064), the GCOE Program The Next Generation of Physics, Spun from Universality and Emergence from MEXT of Japan, FIRST program, JST CREST, and the Impulsing Paradigm Change through Disruptive Technologies (ImPACT) program.

PY - 2016/4/20

Y1 - 2016/4/20

N2 - A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose-Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.

AB - A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose-Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.

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Laser spectroscopic probing of coexisting superfluid and insulating states of an atomic Bose-Hubbard system

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