TY - JOUR

T1 - Spatially overlapped partners in quantum field theory

AU - Trevison, Jose

AU - Yamaguchi, Koji

AU - Hotta, Masahiro

N1 - Publisher Copyright:
© 2019 IOP Publishing Ltd.

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

KW - black hole

KW - quantum entanglement

KW - quantum field theory

KW - quantum memory

KW - spatially overlapped partners

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U2 - 10.1088/1751-8121/ab065b

DO - 10.1088/1751-8121/ab065b

M3 - Article

AN - SCOPUS:85063419750

SN - 1751-8113

VL - 52

JO - Journal of Physics A: Mathematical and Theoretical

JF - Journal of Physics A: Mathematical and Theoretical

IS - 12

M1 - 125402

ER -