Conveners
Symposia talks
- Matthias Gohlke (Okinawa Institute of Science and Technology Graduate University)
Symposia talks
- Kenji Harada (Graduate School of Informatics, Kyoto University)
Symposia talks
- Chisa Hotta (University of Tokyo)
Symposia talks
- Tomotoshi Nishino (Kobe University)
Symposia talks
- Rongyang Sun
Symposia talks
- Masahiko G. Yamada (SQAI, UTokyo)
Symposia talks
- Kouichi Okunishi (Niigata University)
Symposia talks
- Koudai Sugimoto (Keio University)
Generative modeling is a crucial task in the field of machine learning. Recently, there have been several proposals for generative models on quantum devices. We can efficiently optimize generative models defined by tensor network states, but their performance largely depends on the geometrical structure of the tensor network. To tackle this issue, we have proposed an optimization method for...
Quantum Convolutional Neural Networks (QCNNs) have emerged in recent years, demonstrating success, especially in the domain of quantum phase recognition problems. However, the practical application of QCNNs to real-world problem-solving demands further cost reduction and improvement in performance. To address these challenges, this study introduces a novel solution through the introduction of...
In recent years, Variational Quantum Algorithms (VQA) have been actively studied as a promising approach on Noisy Intermediate Scale Quantum computers (NISQ). VQA solve problems by minimizing a cost function through the updating of parameters in a variational quantum circuit on a classical computer. Quantum Machine Learning (QML), which utilizes variational quantum circuits for machine...
We discuss the recent progress in the application of the tensor renormalization group method toward lattice quantum chromodynamics. In the first half, we discuss the application of the Grassmann tensor network for gauge theories with multiple fermion flavors. With the multilayer tensor network construction, it is possible to compute the two-dimensional abelian gauge theories up to 4 flavors....
Parton Distribution Functions (PDFs) describe universal properties of bound states in high energy physics and allow to predict scattering amplitudes in processes with large momentum transfer. The numerical calculation of PDFs involves the evaluation of a Wilson line along a lightcone. In contrast to Monte Carlo simulations in euclidean spacetime, the evolution on a lightcone can be directly...
Thermodynamic properties of the classical Ising model on a hierarchical lattice is studied by tensor network methods. The lattice consists of pentagons, where 2, 3 or 4 of them meet at each vertex, which is the lattice site. Taking the spin configuration sum other than the lowest spin row, we obtain the boundary state at the bottom of the system. This summation can be performed numerically by...
In recent years, matrix product state (MPS) numerics have emerged as the method of choice for examining the low-energy physics of many-body quantum systems in one spatial dimension, as well as small-width 2D systems. While the density matrix renormalisation group (DMRG) algorithm is used to calculate ground states, analysis of the low-lying excitations is typically doing using time-evolution...
The SSH model, describing a one-dimensional chain of atoms or sites with alternating coupling
strengths, exhibits topological solitons in the form of domain walls or edge states. These topological
solitons are the results of the topological nature of the SSH model, and different symmetries can protect
the existence and stability of these solitons. In this work, we explore the effects of...
Computational complexity of physical states is a critical topic because it relates to the preparation on classical or quantum computers, as well as in real experiments. From the perspective of computational complexity theory, thermal and ground states of one-dimensional systems are well-understood. There exists an efficient classical algorithm for calculating thermal states at temperatures...
The quantum state preparation of probability distributions is an important subroutine for many quantum algorithms. When embedding $D$-dimensional multivariate probability distributions by discretizing each dimension into $2^n$-point, we need a state preparation circuit comprising a total of $nD$ qubits, which is often difficult to compile. In this study, we propose a method to generate state...
We propose a protocol to design an exact MPS as a ground state of the bulk Hamiltonian based on cluster units that share their sites with the neighboring clusters.
We first decide what kind of clusters we use, and define a state that we want to have on each cluster as constituents of the local density matrix.
By entangling these clusters by partially projecting out the components that we...
Besides the exactly solvable spin-1/2 Kitaev model, higher spin-$S$ ones, not exactly solvable, are promising playgrounds for researches on the quantum spin liquid as well. As one of main interests in higher spin-$S$ cases, the interplay between the Kitaev spin liquid (KSL) and spin nematics has attracted attentions, which may lead to novel quantum properties of matters. However, this is far...
We show that the matrix product state provides a thermal quantum pure state representation in equilibrium in two spatial dimensions over the entire temperature range. We use the Kitaev honeycomb model as a prominent, non-trivial example hosting a quantum spin liquid ground state. Our method is able to qualitatively capture the double-peak in the specific heat, which was previously obtained...
Quantum error mitigation methods are designed to eliminate the effect of noise in quantum computation by introducing a trade-off between bias and variance, using modified quantum circuits and classical postprocessing. While various techniques have been proposed with their own advantages and disadvantages, there is still no universal criterion to choose the best method for a given application....
While the variational quantum eigensolver (VQE) is widely used today, the imaginary-time evolution (ITE) on a quantum computer is a promising formalism for obtaining the ground state of a quantum system. We proposed recently an algorithm for finding the optimal molecular geometries [1] based on the the probabilistic ITE (PITE) [2] for a first-quantized molecular system. We discuss the...
Estimating physical properties for unknown quantum states is a crucial matter spanning various domains, including quantum information processing, quantum physics, and quantum chemistry. In the realm of quantum computation, existing research has predominantly focused on comprehensive state tomography or estimating specific observables with known classical descriptions. However, a notable gap...
Protected edge modes are one of the most exotic phenomena in contemporary condensed matter physics. In this presentation, I show a general quantum Hamiltonian formalism to the protected edge modes based on the recent development of bulk and boundary renormalization groups. Our formalism gives a way to express a series of boundary phenomena in contemporary physics in a concise way. Generalized...
We study salient information and correlation measures, namely, entanglement entropy, reflected entropy, Markov gap and timelike entanglement entropy in the 1+1D massless Lifshitz field theory that follows anisotropic scaling along temporal and spatial directions. We introduce a continuous family of Lifshitz scale invariant degenerate Rokhsar-Kivelson ground states for our chosen theory with...
We discuss a holographic aspect of the Bethe lattice Ising model, which is a classic model of the phase transition in statistical mechanics and, at the same time, the simplest example of the tree tensor network. We analytically formulate a holographic renormalization group for the model and explain how the power-law decay of the boundary spin correlations emerges based on the network geometry....
Laser technology has made remarkable progress recently, opening new possibilities for nonequilibrium physics experiments. One of the exciting phenomena is quantum phase transitions induced by pulse irradiation, which lead to nonequilibrium metal-superconductor transitions. However, the theoretical analysis of these phenomena is challenging, as it requires computing the dynamic correlation...
Phenomena induced by dc electric fields in strongly correlated electron systems, such as Mott breakdown and field-induced magnetism, have been widely discussed both experimentally and theoretically. Recently, intense terahertz light pulses generated from synchrotron radiation have attracted particular attention as a method for observing these phenomena [1] since the energy of terahertz light...
The quantum coherent screening of a local spin is an essential concept of quantum impurity problems. In this work, we theoretically analyze the quantum coherent screening by using quantum entanglement. We develop a method to compute the entanglement negativity between the impurity spin and electrons in spin-1/2 impurity problems, based on the boundary conformal field theory and numerical...
Solving the Anderson impurity model typically involves a two-step process, where one first calculates the ground state of the Hamiltonian, and then computes its dynamical properties to obtain the Green's function. Here we propose a hybrid classical/quantum algorithm where the first step is performed using a classical computer to obtain the tensor network ground state as well as its quantum...
Based on the previous idea of implementing SU(N) symmetries in the density matrix renormalization group (DMRG) [1], we invented a new algorithm, which has been helpful in extending the previous standard-Young-tableaux approach to generic two-dimensional models, for SU(N)-symmetric DMRG [2]. This new algorithm intensively uses the so-called 9ν coefficients of SU(N) irreducible representations,...
Classical simulation of current noisy intermediate-scale quantum (NISQ) devices forwards the development of all the research directions in near-term quantum computing. While the simulation algorithms based on tensor network states can efficiently simulate a NISQ device with around 100 qubits, restricted by the real-space sequential nature of these algorithms, efficiently simulating a NISQ...
