This is a seminar jointly organized by the two groups working on quantum physics and technology at Department of Physics, Kindai University, namely Condensed-Matter Theory (CMT) and QMB Laboratories.
Scheduled talks
Fiscal year 2026
Time and date: 15:00-, April 8, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Sidharth Rammohan (QMB)
Title: Cluster mean-field analysis on quantum dynamics in a planar array
of hardcore Bose-Hubbard chains with interchain interactions
Abstract: Dipolar bosons in optical lattices offer a versatile platform for quantum simulation, as their long-range and anisotropic interactions give rise to strongly correlated many-body phenomena. These properties have attracted significant experimental and theoretical interest in the study of emergent quantum phases [1,2]. In one-dimensional (1D) settings, such systems exhibit a collective behavior that can be effectively described by Luttinger liquid (LL) theory. Extending this framework to arrays of weakly coupled one-dimensional chains naturally raises the question of how interchain interactions lead to new quantum phases. In this context, the sliding Luttinger liquid (SLL) phase has been proposed as a stable state of weakly coupled 1D chains, where each chain retains its Luttinger-liquid character while interchain interactions enable phase sliding without establishing long-range order [3]. Realizing the SLL phase experimentally is challenging, as it requires strong interchain interactions while keeping the fluctuations minimal. Dipolar ultracold atomic systems, with their tunable long-range interactions, offer a promising platform for observing such a phase, and have consequently motivated theoretical studies exploring planar arrays of dipolar bosons as a route to realizing it [4]. However, existing theoretical studies have focused on equilibrium properties, and real-time dynamics of these systems remain relatively unexplored.
Time and date: 15:00-, April 15, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Jose Carlos Pelayo (QMB)
Title: Multipolar structure in a Rydberg chain with a Four-level Förster resonance
Abstract: We investigate a chain of four-level Rydberg atoms exhibiting both two-level and four-level Förster resonances, the latter enabled by a local light field [1]. We analyze the system using a mean-field approach based on an effective spin-1/2 representation near the degenerate levels, and compare it with a full spin-3/2 mean-field treatment. Within the effective spin-1/2 description, we identify XY ferromagnetic, XY antiferromagnetic phases [2] and Ising Néel. Mapping these states back to the full spin-3/2 Hilbert space reveals an associated multipolar structure, that is pronounced near the four-level Förster resonance. These results are compared against matrix product state (MPS) calculations.
[1] Emperauger, Gabriel, et al. "Benchmarking direct and indirect dipolar spin-exchange interactions between two Rydberg atoms." Physical Review A 111 no. 6 (2025)
[2] Chen, Cheng, et al. "Continuous symmetry breaking in a two-dimensional Rydberg array." Nature 616 no. 7958 (2023)
Time and date: 15:00-, April 22, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Rito Furuchi (QMB)
Title: Domain formation dynamics in Rydberg-atom arrays described by a mixed-field Ising model on a square lattice
Abstract: Rydberg-atom systems have recently attracted considerable attention as highly controllable platforms for quantum simulation and quantum computation. Because both the spatial arrangement of atoms and the interactions induced by Rydberg excitation can be controlled, these systems provide a suitable platform for investigating nonequilibrium dynamics. In particular, a Rydberg-atom system can be described by mapping the ground and excited states of each atom onto pseudospin states can be described by a S=1/2 mixed-field Ising model [1]. Recent experiments [2] using such a Rydberg-atom system have addressed quantum dynamics after a quantum quench of the transverse and longitudinal fields starting from a fully polarized (all spin-down) state. It has been found that when a resonance condition called facilitation condition is satisfied, the cluster size of up-spin domains significantly grows in time [2].
In this study, aiming to understand mechanisms of the observed domain-formation dynamics, we theoretically investigate the quench dynamics in a relatively small system, where we can diagonalize the full Hamiltonian of the system and calculate the time evolution of an initial state using the resulting eigenvalues and eigenvectors. We discuss characteristic features of the time evolution by comparing them with the predictions of a pseudo-analytical perturbation theory that treats the transverse field as a perturbation.
[1]A. Browaeys and T. Lahaye, Nat. Phys. 16, 132 (2020).
[2] Philip Osterholz et al. arXiv preprint arXiv:2512.04656v2 (2026).
Time and date: 15:00-, May 7, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Kanata Oku (CMT)
Title: TBA
Abstract: TBA
Time and date: 15:00-, May 13, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Edwin Chaparro (JILA, University of Colorado)
Title: Bidirectional Teleportation Using Scrambling Dynamics: A Practical Protocol
Abstract: We show that quantum information scrambling can enable a generic SWAP gate between collective degrees of freedom in systems without universal local control. Our protocol combines the Hayden–Preskill recovery scheme, associated with the black hole information paradox, with quantum teleportation and runs them in parallel and in opposite directions, enabling bidirectional exchange of quantum states through global interactions alone. This approach cleanly distinguishes the roles of information spreading, entanglement, and chaos for enabling both coherent state transfer and recovery. We propose an experimental realization using the Dicke model, which can be realized in cavity-QED and trapped-ion platforms, highlighting the utility of holography in designing practical quantum gates.
Time and date: 15:00-, May 20, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Daiki Kawasaki（QMB）
Title: TBA
Abstract: TBA
Time and date: 15:00-, June 3, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Kohei Shono (Quantum Field Theory and Elementary Particle Theory Group)
Title: TBA
Abstract: TBA
Time and date: 15:00-, June 10, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Mengxuan Xia (Quantum Field Theory and Elementary Particle Theory Group)
Title: TBA
Abstract: TBA
Time and date: 15:00-, June 17, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Hiraki Yoshida (CMT)
Title: TBA
Abstract: TBA
Time and date: 15:00-, June 24, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Spearker: Rintarou Kobayasyi（QMB）
Title: TBA
Abstract: TBA
Time and date: 15:00-, July 1, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Airi Tanaka (CMT)
Title: TBA
Abstract: TBA
Time and date: 15:00-, July 8, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Takumi Yuri (Osaka University)
Title: TBA
Abstract: TBA
Time and date: 15:00-, July 15, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Kosei Yoshimoto (QMB)
Title: TBA
Abstract: TBA
Time and date: 15:00-, July 22, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: Genki Watanabe (Institute for Molecular Science)
Title: TBA
Abstract: TBA
Time and date: 15:00-, July 29, 2026
Room: Meeting room for Mathematics and Physics Departments, 4rd Florr, 31 East Building + Webcast via Zoom
Speaker: TBA
Title: TBA
Abstract: TBA