arXiv subjects

Jose Trevison

Publications and source records attributed to Jose Trevison.

4 recordsLinked to original sources

arXiv2019

Spatially Overlapped Partners in Quantum Field Theory

In quantum field theory particles are physically defined as what Unruh-DeWitt 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-Roberson-Walker universe.

gr-qc↗

arXiv2018

Pure State Entanglement Harvesting in Quantum Field Theory

Quantum fields in vacuum states carry an infinite amount of quantum entanglement, and its entanglement entropy has the ultraviolet divergence. Harvesting protocols of the vacuum entanglement had been investigated, but its efficiency is very low to date. The main reason of 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 the 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.

quant-ph↗

arXiv2016

Gravitational Memory Charges of Supertranslation and Superrotation on Rindler Horizons

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.

gr-qc↗

arXiv2015

Quantum Energy Teleportation across a three-spin Ising chain in a Gibbs State

In general, it is important to identify what is the informational resource for quantum tasks. Quantum energy teleportation (QET) is a quantum task, which attains energy transfer in an operational meaning by local operations and classical communication, and is expected to play a role in future development of nano scale smart grids. We consider QET protocols in a three-element Ising spin system with non periodic boundary conditions coupled to a thermal bath. The open chain is the minimal model of QET between two edge spins that allows the measurement and operation steps of the QET protocol to be optimized without restriction. It is possible to analyze how two-body correlations of the system, like mutual information, entanglement and quantum discord, can be resources of this QET at each temperature. In particular, we stress that quantum discord is not the QET resource in some cases even if arbitrary measurements and operations are available.

quant-ph↗