arXiv subjects

Satoru Shoji

Publications and source records attributed to Satoru Shoji.

4 recordsLinked to original sources

arXiv2026

Variational Quantum Operator Simulation

Implementing time-evolution operators in shallow quantum circuits is important for quantum simulations. The standard method of Trotterization requires a large number of gates to achieve practical accuracy. Variational Quantum Simulation (VQS) is an algorithm that calculates the time evolution of a quantum state and can be executed with shallower circuits than Trotterization. However, the operator obtained by VQS evolves only a fixed initial state and is not the time evolution operator itself. In this paper, we propose Variational Quantum Operator Simulation (VQOS), a method to realize time evolution operators in shallow quantum circuits. This method is based on the variational principle for operators and does not require the implementation of the desired Trotter decomposition of the time evolution operator. We performed numerical simulations of the VQOS algorithm and successfully implemented the time evolution operator for closed systems in a quantum circuit that is up to 5 times shallower than the Trotterization. By providing a more practical way to implement time evolution operators, VQOS increases the applicability of near-term quantum computers.

quant-ph↗

arXiv2026

Visualization of Three-Qubit Pure States with Separation of Local and Nonlocal Degrees of Freedom

Understanding the structure of multi-qubit quantum states is essential for both quantum information research and education, yet intuitive visualization beyond the single-qubit Bloch sphere remains challenging. In this work, we propose a unified geometric framework for visualizing two- and three-qubit pure states in which local degrees of freedom and entanglement degrees of freedom are explicitly separated. For two qubits, we combine Bloch-sphere representations of reduced density operators with a complex concurrence plotted on the complex plane, enabling simultaneous visualization of entanglement strength and phase structure. For three qubits, building on the generalized Schmidt decomposition, we introduce bipartite and GHZ-type tripartite complex concurrences, which, together with local Bloch vectors, provide a complete coordinate representation of the state. Unlike classification-based approaches, our method focuses on representing a given concrete state, revealing how local properties and nonlocal correlations coexist. The framework distinguishes states with identical entanglement magnitudes but different interference structures and provides intuitive insight into the balance between pairwise and genuinely tripartite entanglement. This approach offers both conceptual clarity and potential applications in quantum education and state analysis.

quant-ph↗

arXiv2020

Optical combs and optical vortices combined for spatiotemporal manipulation of light and matter

In this study, we demonstrate the concept of combining optical combs with optical vortices for the first time. By combining the advantages of the both light sources, we realize an optical vortex comb technology for arbitrary spatiotemporal phase manipulation. This idea corresponds to simultaneous control of the longitudinal and transverse modes of light based on the high controllability of the optical comb. As a proof-of-concept experiment, we applied an optical vortex comb to the generation and rotational control of a ring-shaped optical lattice. Furthermore, to demonstrate the utility of this technique, a rotational optical manipulation of microspheres was demonstrated using the optical ring lattice as an optical tweezer light. Here, we present a new applicability of the optical comb by utilizing its characteristics far beyond the conventional range.

physics.optics↗

arXiv2001

Self-written waveguides in photopolymerizable resins

We study the optically-induced growth and interaction of self-written waveguides in a photopolymerizable resin. We investigate experimentally how the interaction depends on the mutual coherence and relative power of the input beams, and suggest an improved analytical model that describes the growth of single self-written waveguides and the main features of their interaction in photosensitive materials.

nlin.PS↗