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Zi Yang Meng ( 孟子杨 ) Institute of Physics, Chinese Academy of Sciences Determinantal Quantum Monte Carlo: Algorithm and Measurements

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Page 1: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Zi Yang Meng

( 孟子杨 )

Institute of Physics, Chinese Academy of Sciences

Determinantal Quantum Monte Carlo: Algorithm and Measurements

Page 2: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

World-line QMC for bosons

Determinantal QMC for fermionsHubbard model: Metal-Insulator transition Unconventional superconductivity Non-Fermi-liquid Interaction effects on topological state of

matter…...

Heisenberg model: Quantum magnetism Phase transition and critical phenomena Quantum spin liquids Quantum spin ice…...

Quantum Monte Carlo

Page 3: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Basic problem

Partition function:

Observables :

Fock space :

Page 4: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Determinantal quantum Monte Carlo

Path-integral & Trotter-Suzuki decomposition

Free fermion (Slater) determinant

Page 5: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Determinantal quantum Monte Carlo

Path-integral & Trotter-Suzuki decomposition

Discrete Hubbard-Stratonovich transformation

➢ Blankenbecler et. al., Phys. Rev. D 24, 2278 (1981)➢ Hirsch, Phys. Rev. B 28, 4059(R) (1983)➢ Hirsch, Phys. Rev. B 31, 4403 (1985)➢ Assaad and Evertz, Lec. Notes. In Phys. 739 (2008)

Page 6: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Determinantal quantum Monte Carlo

Path-integral & Trotter-Suzuki decomposition

Discrete Hubbard-Stratonovich transformation

➢ Blankenbecler et. al., Phys. Rev. D 24, 2278 (1981)➢ Hirsch, Phys. Rev. B 28, 4059(R) (1983)➢ Hirsch, Phys. Rev. B 31, 4403 (1985)➢ Assaad, Phys. Rev. B 71, 075103 (2005)➢ Assaad and Evertz, Lec. Notes. In Phys. 739 (2008)

Page 7: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Determinantal quantum Monte Carlo

Write Path-integral into determinant

Monte Carlo sampling in configuration space

Page 8: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Quantum Monte Carlo

Hubbard-Stratonovich Transformation

QMC measurements

Page 9: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Quantum Monte Carlo

System sizes:

Time discretization:

Computation effort scales linearly with

Parallelization: ~ 103 CPUs, ~ 106 CPU hours

Tianhe-1 Tianhe-2

Page 10: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Square lattice Hubbard model

➢ C. Chen, Bachelor Thesis (2016)

Page 11: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Square lattice Hubbard model

➢ C. Chen, Bachelor Thesis (2016)

Page 12: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition

Square lattice Hubbard model

➢ C. Chen, Bachelor Thesis (2016)

Page 13: Determinantal Quantum Monte Carlo: Algorithm …ziyangmeng.iphy.ac.cn/.../SummerSchoolDQMC201608_ppt.pdfDeterminantal quantum Monte Carlo Path-integral & Trotter-Suzuki decomposition