Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1361-6382/ac2c1e

Other Link： https://iopscience.iop.org/article/10.1088/1361-6382/ac2c1e/pdf

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevD.101.105009

Scopus

Authorship：Lead author,　Corresponding author  

DOI： 10.11316/butsuri.75.5_284

Authorship：Last author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.physleta.2019.126078

Scopus

Publishing type：Research paper (scientific journal)  

DOI： 10.7566/JPSJ.89.054005

Scopus

Authorship：Last author   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevD.101.085017

Scopus

Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevD.101.024003

Scopus

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.physleta.2020.126447

Scopus

Authorship：Lead author,　Last author,　Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.7566/JPSJ.88.064002

Scopus

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.physleta.2019.01.036

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Physics Publishing  

In quantum field theory particles are physically defined as what Unruh-De Witt particle detectors observe. By detecting a particle mode A, a reduced density operator for a quantum state of A is constructed. Even if the entire quantum state of the quantum field is pure, the state of A is not pure but mixed due to entanglement between other subsystems. The partner mode B of the field is defined as a purification partner of A such that the AB system in a pure state. We show that, without any fine-tuning of the particle detector design of A, the weighting function of partner B has spatial overlap of that of A. We show a general formula of partner B associated with arbitrarily fixed A of a free field in a general Gaussian state. We demonstrate an example of memory effects in an expanding Freedman-Robertson-Walker universe.

DOI： 10.1088/1751-8121/ab065b

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Physical Society of Japan  

Quantum fields in vacuum states carry an infinite amount of quantum entanglement, and its entanglement entropy has ultraviolet divergence. Harvesting protocols of the vacuum entanglement have been investigated, but its efficiency is very low to date. The main reason for the low efficiency originates from the fact that the extracted entanglement is embedded in a mixed state of two external devices. We propose a general protocol with high efficiency by extracting pure state entanglement from the field. We only use bi-linear interactions between the fields and external devices. Even though the ultraviolet cutoff remains finite, the protocol is capable of extracting a huge amount of entanglement. Hence an infinite amount of entanglement extraction is attained without the ultraviolet divergence of the field entanglement entropy in a continuum limit. There exists a trade-off relation between the extracted entanglement and its energy cost.

DOI： 10.1093/ptep/pty109

Scopus

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society  

We propose a model with multiple qubits that reproduces the thermal properties of four-dimensional Schwarzschild black holes (BHs) by simultaneously taking account of the emission of Hawking particles and the zero-energy soft-hair evaporation at the horizon. The results verify that the entanglement entropy between a qubit and other subsystems, including emitted radiation, is much larger than the BH entropy analogue of the qubit, as opposed to the Page curve prediction. Our result suggests that early Hawking radiation is entangled with soft hair and that late Hawking radiation can be highly entangled with the degrees of freedom of a BH, avoiding the emergence of a firewall at the horizon.

DOI： 10.1103/PhysRevLett.120.181301

Scopus

PubMed

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

In a Rindler-type coordinate system spanned in a region outside of a black hole horizon, we have nonvanishing classical holographic charges as soft hairs on the horizon for stationary black holes. Taking a large black hole mass limit, the spacetimes with the charges are described by asymptotic Rindler metrics. We construct a general theory of gravitational holographic charges for a (1 + 3)-dimensional linearized gravity field in the Minkowski background with Rindler horizons. Although matter crossing a Rindler horizon causes horizon deformation and a time-dependent coordinate shift-that is, gravitational memory-the supertranslation and superrotation charges on the horizon can be defined during and after its passage through the horizon. It is generally proven that holographic states on the horizon cannot store any information about absorbed perturbative gravitational waves. However, matter crossing the horizon really excites holographic states. By using gravitational memory operators, which consist of the holographic charge operators, we suggest a resolution of the no-cloning paradox of quantum information between matter falling into the horizon and holographic charges on the horizon from the viewpoint of the contextuality of quantum measurement.

DOI： 10.1103/PhysRevD.94.083001

Web of Science

Language：Japanese   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Poster presentation  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)