40 citations · 67 across the 10 of their papers we have counts for
10 papers
Landau Theory for Commensurate Charge-Density Waves Coupled to Uniform Lattice Deformation
Keiji Nakatsugawa, Toshiyuki Fujii, Satoshi Tanda
We formulate a minimal Landau theory for a charge-density wave (CDW) whose commensurability is defined with respect to a deformed lattice. The motivation is provided by recent obse…
Massive Klein Tunneling in Topological Photonic Crystals
Keiji Nakatsugawa, Xiao Hu
Klein's paradox refers to the transmission of a relativistic particle through a high potential barrier. Although it has a simple resolution in terms of particle-to-antiparticle tun…
Revisitation of the lock-in transition in one-dimensional charge-density waves
Katsuhiko Inagaki, Keiji Nakatsugawa, Satoshi Tanda
We studied the lock-in transition of charge-density waves of one-dimensional conductors. Though this phenomenon has been known for decades, there are still discrepancies between th…
Conformality of Charge Density Wave
Keiji Nakatsugawa, Tatsuhiko N. Ikeda, Takeshi Toshima +1
New quantum phenomena are continuously being discovered in 2D systems. In particular, the charge density wave (CDW) has the aspect of a quantum crystal with a macroscopic wave func…
The Nakano-Nishijima-Gell-Mann Formula From Discrete Galois Fields
Keiji Nakatsugawa, Motoo Ohaga, Toshiyuki Fujii +2
The well known Nakano-Nishijima-Gell-Mann (NNG) formula relates certain quantum numbers of elementary particles to their charge number. This equation, which phenomenologically intr…
Origin of Stripe and Quasi-Stripe CDW Structures in Monolayer MX compounds: Multivalley Free Energy Landscape
Keiji Nakatsugawa, Satoshi Tanda, Tatsuhiko N. Ikeda
Ultrathin sheets of transition metal dichalcogenides (MX) with charge density waves (CDWs) is increasingly gaining interest as a promising candidate for graphene-like devices.…
Time Operators and Time Crystals
K. Nakatsugawa, T. Fujii, A. Saxena +1
We investigate time operators in the context of quantum time crystals in ring systems. A generalized commutation relation called the generalized weak Weyl relation is used to deriv…
Direct Observation of Mono-, Bi-, and Tri-layer Charge Density Waves in 1T-TaS_2 by Transmission Electron Microscopy without a Substrate
Daiki Sakabe, Zheng Liu, Kazumoto Suenaga +2
Charge-density-waves (CDW) which occur mainly in low-dimensional systems have a macroscopic wave function similar to superfluids and superconductors. Kosterlitz-Thouless (KT) trans…
Quantum Time Crystal By Decoherence: Proposal With Incommensurate Charge Density Wave Ring
Keiji Nakatsugawa, Toshiyuki Fujii, Satoshi Tanda
We show that time translation symmetry of a ring system with a macroscopic quantum ground state is broken by decoherence. In particular, we consider a ring-shaped incommensurate ch…
Incommensurate Charge Density Wave as Quantum Space-Time Crystal
Keiji Nakatsugawa, Toshiyuki Fujii, Satoshi Tanda
A quantum time crystal (QTC) is a novel quantum mechanical ground state that was recently proposed by Wilczek. Although many QTC models have been proposed, it is not clear yet if s…