The $S=1/2$ square-lattice $J\text{\ensuremath{-}}Q$ model hosts a deconfined quantum phase transition between antiferromagnetic and dimerized (valence-bond solid) ground states. We here study two deformations of this model---a term projecting staggered singlets, as well modulation the $J$ terms forming alternating ``staircases'' strong weak couplings. first deformation preserves all lattice symmetries. Using Monte Carlo simulations, we show that it nevertheless introduces second relevant...

Abstract We study the tractability of classically simulating critical phenomena in quench dynamics one-dimensional transverse field Ising models (TFIMs) using highly truncated matrix product states (MPS). focus on two paradigmatic examples: a dynamical quantum phase transition (DQPT) that occurs nonintegrable long-range TFIMs, and infinite-time correlation length integrable nearest-neighbor TFIM when quenched to point, where quantities interest involve equal time one- two- point functions,...

We introduce a quantum spin-1/2 model with many-body correlated Heisenberg-type interactions on the two-dimensional square lattice, designed so that system can host fourfold degenerate plaquette valence-bond solid (PVBS) ground state spontaneously breaks Z4 symmetry. The is sign-problem free and amenable to large-scale Monte Carlo simulations, thus allowing us carry out detailed study of phase transition between standard Néel antiferromagnetic (AFM) PVBS states. find first-order transition,...

We resolve the nature of quantum phase transition between a N\'eel antiferromagnet and valence-bond solid in two-dimensional spin-1/2 magnets. study class $J$-$Q$ models, which Heisenberg exchange $J$ competes with interactions $Q_n$ formed by products $n$ singlet projectors on adjacent parallel lattice links. QMC simulations provide unambiguous evidence for first-order transitions, discontinuities increasing $n$. For $n=2$ $n=3$ signatures are very weak. On intermediate length scales, we...

We propose a new concept for Ba-ferrite coated disk, in which the particles are longitudinally oriented and to acicular Co-γFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> powder is also added, achieve high density recording low noise characteristics rigid disk applications. By using ring head, longitudinal orientation was found be effective obtaining an increased output symmetrical...

Study on ac loss characteristics of HTS coils with an iron core to simulate armature winding rotational machine and a method reduce losses in combined the 3-phase condition are reported this paper. In study, test model which combines 6 wound by YBCO tapes used for conventional induction motor is fabricated measurement. It shown that measured coincides sum each phase 1-phase condition. The effectiveness suppress perpendicular magnetic field applied tape coil use materials around reduction...

Liu et al. [Phys. Rev. B 98, 241109 (2018)] used Monte Carlo sampling of the physical degrees freedom a projected entangled pair state type wave function for $S=1/2$ frustrated ${J}_{1}\ensuremath{-}{J}_{2}$ Heisenberg model on square lattice and found nonmagnetic argued to be gapless spin liquid when coupling ratio $g={J}_{2}/{J}_{1}$ is in range $g\ensuremath{\in}[0.42,0.6]$. Here we show that their definition order parameter another candidate ground within this window---a spontaneously...

Understanding and approximating extremal energy states of local Hamiltonians is a central problem in quantum physics complexity theory. Recent work has focused on developing approximation algorithms for Hamiltonians, particular the ``Quantum Max Cut'' (QMax-Cut) problem, which closely related to antiferromagnetic Heisenberg model. In this work, we introduce family semidefinite programming (SDP) relaxations based Navascues-Pironio-Acin (NPA) hierarchy tailored QMaxCut by taking into account...

We use quantum Monte Carlo simulations to study a $S=1/2$ spin model with competing multi-spin interactions. find phase transition between columnar valence-bond solid (cVBS) and N\'eel antiferromagnet (AFM), as in the scenario of deconfined quantum-critical points, well AFM staggered (sVBS). By continuously varying parameter, sVBS--AFM AFM--cVBS boundaries merge into direct sVBS--cVBS transition. Unlike previous models putative transitions, e.g., standard $J$-$Q$ model, our extended cVBS...

Chaos computing is a non-traditional new paradigm that exploits the extreme non-linearity of chaotic systems. This article presents unified theoretical view chaos computing. It introduces fundamental concept and unique features are characteristics computing, discusses various implementation approaches. Basic aspects digital to realise logical gates introduced, followed by two specific techniques: (1) direct utilisation threshold mechanisms; (2) an application neuron model. After presenting...

A recently proposed exact algorithm for the maximum independent set problem is analyzed. The typical running time improved exponentially in some parameter regions compared to simple binary search. also overcomes core transition point, where conventional leaf removal fails, and works up replica symmetry breaking (RSB) point. This suggests that a itself not enough hardness random problem, providing further evidence RSB being obstacle algorithms general.

Quantum Monte Carlo (QMC) methods have proven invaluable in condensed matter physics, particularly for studying ground states and thermal equilibrium properties of quantum Hamiltonians without a sign problem. Over the past decade, significant progress has also been made on their rigorous convergence analysis. Heisenberg antiferromagnets (AFM) with bipartite interaction graphs are popular target computational QMC studies due to physical importance, but despite apparent empirical efficiency...

Several power-law critical properties involving different statistics in natural languages -- reminiscent of scaling physical systems at or near phase transitions have been documented for decades. The recent rise large language models (LLMs) has added further evidence and excitement by providing intriguing similarities with notions physics such as laws emergent abilities. However, specific instances classes generative that exhibit transitions, understood the statistical community, are...

As a signal recovery algorithm, compressed sensing is particularly effective when the data has low complexity and samples are scarce, which aligns natually with task of quantum phase estimation (QPE) on early fault-tolerant computers. In this work, we present new Heisenberg-limited, robust QPE algorithm based sensing, requires only sparse discrete sampling times. Specifically, given multiple copies suitable initial state queries to specific unitary matrix, our can recover total runtime...

Quantum annealing (QA) for the NP-hard maximum independent set problem with a unique solution is studied using quantum Monte Carlo method. A fraction of samples exhibit first-order phase transitions in terms spin-glass order parameter q. Moreover, while no singularities could be observed sample-averaged , divergence fidelity susceptibility found. Since all q occur smaller transverse field strength compared to point it likely that detected by induces transitions. This suggests failures QA due...

The computational complexity conjecture of NP $\nsubseteq$ BQP implies that there should be an exponentially small energy gap for Quantum Annealing (QA) NP-hard problems. We aim to verify how this computation originated gapless point could understood based on physics, using the quantum Monte Carlo method. As a result, we found phase transition detectable only by divergence fidelity susceptibility. points each instance are all located in study, which suggests is physical cause failure QA

We study the tractability of classically simulating critical phenomena in quench dynamics one-dimensional transverse field Ising models (TFIMs) using highly truncated matrix product states (MPS). focus on two paradigmatic examples: a dynamical quantum phase transition (DQPT) that occurs nonintegrable long-range TFIMs, and infinite-time correlation length integrable nearest-neighbor TFIM when quenched to point. For DQPT, we show order parameters can be efficiently simulated with surprisingly...