Explanipedia

Defects and their Time Scales in Quantum and Classical Annealing of the Two-Dimensional Ising Model Open

Phillip Weinberg, Na Xu, Anders W. Sandvik · 2025

We investigate defects in the two-dimensional transverse-field Ising ferromagnet on periodic $L\times L$ lattices after quantum annealing from high to vanishing field. With exact numerical solutions for $L \le 6$, we observe the expected c…

Dynamic structure factor of a spin-1/2 Heisenberg chain with long-range interactions Open

Sibin Yang, Gabe Schumm, Anders W. Sandvik · 2025

We study the dynamic structure factor $S(k,ω)$ of the spin-1/2 chain with long-range, power-law decaying unfrustrated (sign alternating) Heisenberg interactions $J_r \sim (-1)^{r-1} r^{-α}$ by means of stochastic analytic continuation (SAC…

Equilibration of topological defects near the deconfined quantum multicritical point Open

Yu-Rong Shu, Shao-Kai Jian, Anders W. Sandvik, Shuai Yin · 2025

Deconfined quantum criticality (DQC) arises from fractionalization of quasi-particles and leads to fascinating behaviors beyond the Landau-Ginzburg-Wilson description of phase transitions. Here, we study the critical dynamics when driving …

Single-Particle Dispersion and Density of States of the Half-Filled 2D Hubbard Model Open

Gabe Schumm, Shiwei Zhang, Anders W. Sandvik · 2025

Implementing an improved method for analytic continuation and working with imaginary-time correlation functions computed using quantum Monte Carlo simulations, we resolve the single-particle dispersion relation and the density of states (D…

Comment on: "Dynamics of disordered quantum systems with two- and three-dimensional tensor networks" arXiv:2503.05693 Open

Andrew King, Alberto Nocera, Marek M. Rams, Jacek Dziarmaga, Nitin Kaushal , et al. · 2025

In a recent preprint [1] (arXiv:2503.05693), Tindall et al. presented impressive classical simulations of quantum dynamics using tensor networks. Their methods represent a significant improvement in the classical state of the art, and in s…

Beyond-classical computation in quantum simulation Open

Andrew King, Alberto Nocera, Marek M. Rams, Jacek Dziarmaga, Roeland Wiersema , et al. · 2025

Quantum computers hold the promise of solving certain problems that lie beyond the reach of conventional computers. However, establishing this capability, especially for impactful and meaningful problems, remains a central challenge. Here,…

Ground state of the S = 1/2 Heisenberg spin chain with random ferro- and antiferromagnetic couplings Open

Sibei Li, Hui Shao, Anders W. Sandvik · 2024

We study the Heisenberg $S=1/2$ chain with random ferro- and antiferromagnetic couplings using quantum Monte Carlo simulations at ultra-low temperatures, converging to the ground state. Finite-size scaling of correlation functions and exci…

Multiscale Excitations in the Diluted Two-dimensional S = 1/2 Heisenberg Antiferromagnet Open

Liuyun Dao, Hui Shao, Anders W. Sandvik · 2024

We study the excitation spectrum of the $S=1/2$ Heisenberg model on the randomly diluted square lattice by analytic continuation of QMC data. At dilution fractions $p=1/16$ and $p=1/8$, the dynamic structure factor $S({\bf q},ω)$ exhibits …

Using operator covariance to disentangle scaling dimensions in lattice models Open

Anders W. Sandvik · 2024

In critical lattice models, distance ($r$) dependent correlation functions contain power laws $r^{-2Δ}$ governed by scaling dimensions $Δ$ of an underlying continuum field theory. In Monte Carlo simulations, the leading dimensions can be e…

Cross Validation in Stochastic Analytic Continuation Open

Gabe Schumm, Sibin Yang, Anders W. Sandvik · 2024

Stochastic Analytic Continuation (SAC) of Quantum Monte Carlo (QMC) imaginary-time correlation function data is a valuable tool in connecting many-body models to experimentally measurable dynamic response functions. Recent developments of …

SO(5) multicriticality in two-dimensional quantum magnets Open

Jun Takahashi, Hui Shao, Bowen Zhao, Wenan Guo, Anders W. Sandvik · 2024

We resolve the nature of the quantum phase transition between a Néel antiferromagnet and a valence-bond solid in two-dimensional spin-1/2 magnets. We study a class of $J$-$Q$ models, in which Heisenberg exchange $J$ competes with interacti…

Primary and secondary order parameters in the fully frustrated transverse-field Ising model on the square lattice Open

Gabe Schumm, Hui Shao, Wenan Guo, Frédéric Mila, Anders W. Sandvik · 2024

Using quantum Monte Carlo simulations and field-theory arguments, we study the fully frustrated transversefield Ising model on the square lattice for the purpose of quantitatively relating two different order parameters to each other. We c…

Beyond-classical computation in quantum simulation Open

Andrew D. King, Alberto Nocera, Marek M. Rams, Jacek Dziarmaga, Roeland Wiersema , et al. · 2024

Quantum computers hold the promise of solving certain problems that lie beyond the reach of conventional computers. However, establishing this capability, especially for impactful and meaningful problems, remains a central challenge. Here,…

Entanglement entropy and deconfined criticality: emergent SO(5) symmetry and proper lattice bipartition Open

Jonathan D’Emidio, Anders W. Sandvik · 2024

We study the Rényi entanglement entropy (EE) of the two-dimensional $J$-$Q$ model, the emblematic quantum spin model of deconfined criticality at the phase transition between antiferromagnetic and valence-bond-solid ground states. State-of…

Primary and Secondary Order Parameters in the Fully Frustrated Transverse Field Ising Model on the Square Lattice Open

Gabe Schumm, Hui Shao, Wenan Guo, Frédéric Mila, Anders W. Sandvik · 2023

Using quantum Monte Carlo simulations and field-theory arguments, we study the fully frustrated (Villain) transverse-field Ising model on the square lattice. We consider a "primary" spin order parameter and a "secondary" dimer order parame…

Equilibration of Topological Defects Near the Deconfined Quantum Multicritical Point Open

Yu-Rong Shu, Shao-Kai Jian, Anders W. Sandvik, Shuai Yin · 2023

Deconfined quantum criticality (DQC) arises from fractionalization of quasi-particles and leads to fascinating behaviors beyond the Landau-Ginzburg-Wilson description of phase transitions. Here, we study the critical dynamics when driving …

Data and simulation codes for "Proximate deconfined quantum critical point in SrCu2(BO3)2" Open

Yi Cui, Lu Liu, Huihang Lin, Kai-Hsin Wu, Wenshan Hong , et al. · 2023

Experimental data and numerical simulation codes for a manuscript titled "Proximate deconfined quantum critical point in SrCu₂(BO₃)₂".

Data and codes for "Proximate deconfined quantum critical point in SrCu2(BO3)2" Open

Yi Cui, Lu Liu, Huihang Lin, Kai-Hsin Wu, Wenshan Hong , et al. · 2023

Experimental data and numerical simulation codes for a manuscript titled "Proximate deconfined quantum critical point in SrCu₂(BO₃)₂".

Data and codes for "Proximate deconfined quantum critical point in SrCu2(BO3)2" Open

Yi Cui, Lu Liu, Huihang Lin, Kai-Hsin Wu, Wenshan Hong , et al. · 2023

Experimental data and numerical simulation codes for a manuscript titled "Proximate deconfined quantum critical point in SrCu₂(BO₃)₂".

Quantum critical dynamics in a 5000-qubit programmable spin glass: data repository Open

Andrew D. King, Jack Raymond, T. Lanting, R. Harris, Alex Zucca , et al. · 2023

Supporting data for "Quantum critical dynamics in a 5000-qubit programmable spin glass", Nature, 2023.

Quantum critical dynamics in a 5000-qubit programmable spin glass: data repository Open

Andrew D. King, Jack Raymond, T. Lanting, R. Harris, Alex Zucca , et al. · 2023

Supporting data for "Quantum critical dynamics in a 5000-qubit programmable spin glass", Nature, 2023.

Progress on stochastic analytic continuation of quantum Monte Carlo data Open

Hui Shao, Anders W. Sandvik · 2022

We report multipronged progress on the stochastic averaging approach to numerical analytic continuation of imaginary-time correlation functions computed by quantum Monte Carlo simulations. After reviewing the conventional maximum-entropy a…

Quantum critical dynamics in a 5000-qubit programmable spin glass Open

Andrew King, Jack Raymond, T. Lanting, Richard Harris, Alex Zucca , et al. · 2022

Experiments on disordered alloys suggest that spin glasses can be brought into low-energy states faster by annealing quantum fluctuations than by conventional thermal annealing. Due to the importance of spin glasses as a paradigmatic compu…

Quantum Spin Liquid Phase in the Shastry-Sutherland Model Detected by an Improved Level Spectroscopic Method Open

Ling Wang, Yalei Zhang, Anders W. Sandvik · 2022

We study the spin-1/2 two-dimensional Shastry–Sutherland spin model by exact diagonalization of clusters with periodic boundary conditions, developing an improved level spectroscopic technique using energy gaps between states with differen…

Proximate deconfined quantum critical point in SrCu2(BO3)2 Open

Yi Cui, Lu Liu, Huihang Lin, Kai-Hsin Wu, Wenshan Hong , et al. · 2022

The deconfined quantum critical point (DQCP) represents a paradigm shift in quantum matter studies, presenting a "beyond Landau" scenario for order--order transitions. Its experimental realization, however, has remained elusive. Using high…

Quantum criticality and spin liquid phase in the Shastry-Sutherland model Open

Jianwei Yang, Anders W. Sandvik, Ling Wang · 2022

Using the density-matrix renormalization group method for the ground state and excitations of the Shastry- Sutherland spin model, we demonstrate the existence of a narrow quantum spin liquid phase between the previously known plaquette-sin…

Progress on stochastic analytic continuation of quantum Monte Carlo data Open

Hui Shao, Anders W. Sandvik · 2022

We report multipronged progress on the stochastic averaging approach to numerical analytic continuation of quantum Monte Carlo data. With the sampled spectrum parametrized with delta-functions in continuous frequency space, a calculation o…

Fractional and composite excitations of antiferromagnetic quantum spin trimer chains Open

Jun-Qing Cheng, Jun Li, Zijian Xiong, Han-Qing Wu, Anders W. Sandvik , et al. · 2022

Using quantum Monte Carlo, exact diagonalization, and perturbation theory, we study the spectrum of the S = 1/2 antiferromagnetic Heisenberg trimer chain by varying the ratio g = J 2 / J 1 of the intertrimer and intratrimer coupling streng…

topological order and first-order quantum phase transitions in systems with combinatorial gauge symmetry Open

Kai-Hsin Wu, Zhi-Cheng Yang, Dmitry Green, Anders W. Sandvik, Claudio Chamon · 2021

We study a generalization of the two-dimensional transverse-field Ising model, combining both ferromagnetic and antiferromagnetic two-body interactions, that hosts exact global and local Z₂ gauge symmetries. Using exact diagonal…

Emergent O(4) symmetry at the phase transition from plaquette-singlet to antiferromagnetic order in quasi-two-dimensional quantum magnets* Open

Guang-Yu Sun, Nvsen Ma, Bowen Zhao, Anders W. Sandvik, Zi Yang Meng · 2021

Recent experiments [Guo et al. , Phys. Rev. Lett. 124 206602 (2020)] on thermodynamic properties of the frustrated layered quantum magnet SrCu 2 (BO 3 ) 2 — the Shastry–Sutherland material — have provided strong evidence for a low-temperat…

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