10 papers · 1 filter
Quantum Complexity of Ancilla-Free Unitary Embeddings for Nonlinear Dynamics via Generalized State-Dependent Double-Bracket Flows
Yuki Ito, Hideaki Hakoshima, Keisuke Fujii
Simulating nonlinear dynamics with quantum computers has gained increasing attention. In general, such simulations require additional quantum resources because unitary quantum evol…
Encoding universal quantum computation into quantized Berry phases: Hardness results and classical algorithms
Kazuki Sakamoto, Keisuke Fujii
The Berry phase is a fundamental geometric quantity for characterizing the geometry and topology of quantum many-body systems. Previous work established a super-polynomial quantum…
Tensor Network Formulation of Dequantized Algorithms for Ground State Energy Estimation
Hidetaka Manabe, Takanori Sugimoto, Keisuke Fujii
Verifying quantum advantage for practical problems, particularly the ground state energy estimation (GSEE) problem, is one of the central challenges in quantum computing theory. Fo…
Out-of-Time-Order Correlator Spectroscopy
Keisuke Fujii
Out-of-time-order correlators (OTOCs) are central probes of quantum scrambling, and their generalizations have recently become key primitives for both benchmarking quantum advantag…
A Quantum Algorithm for Nonlinear Electromagnetic Fluid Dynamics via Koopman-von Neumann Linearization
Hayato Higuchi, Yuki Ito, Kazuki Sakamoto +2
To simulate plasma phenomena, large-scale computational resources have been employed in developing high-precision and high-resolution plasma simulations. One of the main obstacles…
Nontrivial multi-product commutation relation toward reducing T-count in sequential Pauli-based computation
Yusei Mori, Hideaki Hakoshima, Keisuke Fujii
Quantum compilers that reduce the number of T gates are essential for minimizing the overhead of fault-tolerant quantum computation. Achieving further T-count reduction calls for i…
Large-Scale Quantum Device Benchmarking via LXEB with Particle-Number-Conserving Random Quantum Circuits
Takumi Kaneda, Keisuke Fujii, Hiroshi Ueda
Linear cross-entropy benchmarking (LXEB) with random quantum circuits is a standard method for evaluating quantum computers. However, LXEB requires classically simulating the ideal…
On the quantum computational complexity of classical linear dynamics with geometrically local interactions: Dequantization and universality
Kazuki Sakamoto, Keisuke Fujii
The simulation of large-scale classical systems in exponentially small space on quantum computers has gained attention. The prior work demonstrated that a quantum algorithm offers…
Polynomial time constructive decision algorithm for multivariable quantum signal processing
Yuki Ito, Hitomi Mori, Kazuki Sakamoto +1
Quantum signal processing (QSP) and quantum singular value transformation (QSVT) have provided a unified framework for understanding many quantum algorithms, including factorizatio…
How to Map Linear Differential Equations to Schrödinger Equations via Carleman and Koopman-von Neumann Embeddings for Quantum Algorithms
Yuki Ito, Yu Tanaka, Keisuke Fujii
Solving linear and nonlinear differential equations with large degrees of freedom is an important task for scientific and industrial applications. In order to solve such differenti…