TY - JOUR
T1 - Continuous Phase Transition without Gap Closing in Non-Hermitian Quantum Many-Body Systems
AU - Matsumoto, Norifumi
AU - Kawabata, Kohei
AU - Ashida, Yuto
AU - Furukawa, Shunsuke
AU - Ueda, Masahito
N1 - Funding Information:
We are grateful to Zongping Gong, Masaya Nakagawa, Takashi Mori, Hosho Katsura, and Masaki Oshikawa for fruitful discussions. This work was supported by KAKENHI Grant No. JP18H01145 and a Grant-in-Aid for Scientific Research on Innovative Areas “Topological Materials Science” (KAKENHI Grant No. JP15H05855) from the Japan Society for the Promotion of Science (JSPS). N. M. was supported by the JSPS through Program for Leading Graduate Schools (MERIT). K. K. was supported by JSPS KAKENHI Grant No. JP19J21927. Y. A. was supported by JSPS KAKENHI Grants No. JP16J03613 and No. JP19K23424. S. F. was supported by JSPS KAKENHI Grant No. JP18K03446 and Keio Gijuku Academic Development Funds.
Publisher Copyright:
© 2020 American Physical Society.
PY - 2020/12/21
Y1 - 2020/12/21
N2 - Contrary to the conventional wisdom in Hermitian systems, a continuous quantum phase transition between gapped phases is shown to occur without closing the energy gap Δ in non-Hermitian quantum many-body systems. Here, the relevant length scale ζ≃vLR/Δ diverges because of the breakdown of the Lieb-Robinson bound on the velocity (i.e., unboundedness of vLR) rather than vanishing of the energy gap Δ. The susceptibility to a change in the system parameter exhibits a singularity due to nonorthogonality of eigenstates. As an illustrative example, we present an exactly solvable model by generalizing Kitaev's toric-code model to a non-Hermitian regime.
AB - Contrary to the conventional wisdom in Hermitian systems, a continuous quantum phase transition between gapped phases is shown to occur without closing the energy gap Δ in non-Hermitian quantum many-body systems. Here, the relevant length scale ζ≃vLR/Δ diverges because of the breakdown of the Lieb-Robinson bound on the velocity (i.e., unboundedness of vLR) rather than vanishing of the energy gap Δ. The susceptibility to a change in the system parameter exhibits a singularity due to nonorthogonality of eigenstates. As an illustrative example, we present an exactly solvable model by generalizing Kitaev's toric-code model to a non-Hermitian regime.
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U2 - 10.1103/PhysRevLett.125.260601
DO - 10.1103/PhysRevLett.125.260601
M3 - Article
C2 - 33449745
AN - SCOPUS:85099117266
SN - 0031-9007
VL - 125
JO - Physical review letters
JF - Physical review letters
IS - 26
M1 - 260601
ER -