Spatially Overlapped Partners in Quantum Field Theory

Abstract

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.

35 pages, 6 figures. Published version

References in corpus (10)

• Peres-Horodecki separability criterion for continuous variable systems
• Inseparability criterion for continuous variable systems
• Entanglement from the vacuum
• Violating Bell's inequalities in the vacuum
• Novel schemes for measurement-based quantum computation
• Spatial structures and localization of vacuum entanglement in the linear harmonic chain
• A model with cosmological Bell inequalities
• Mode-Wise Entanglement of Gaussian States
• Quantum computation in correlation space and extremal entanglement
• Pure State Entanglement Harvesting in Quantum Field Theory

Cited by in corpus (17)

• Role of thermal field in entanglement harvesting between two accelerated Unruh-DeWitt detectors
• Entanglement harvesting from conformal vacuums between two Unruh-DeWitt detectors moving along null paths
• Minimal energy cost of entanglement extraction
• Entanglement harvesting between two inertial Unruh-DeWitt detectors from non-vacuum quantum fluctuations
• Quantum entanglement in cosmology
• Entanglement structure of quantum fields through local probes
• Superadditivity of channel capacity through quantum fields
• Entangled pairs in evaporating black holes without event horizons
• Non-perturbative method for particle detectors with continuous interactions
• Partner formula for an arbitrary moving mirror in $1+1$ dimensions
• Random pure Gaussian states and Hawking radiation
• Entanglement partners and monogamy in de Sitter universes
• Quantum Information Capsule in Multiple-Qudit Systems and Continuous-Variable Systems
• Entanglement and correlations between local observables in de Sitter spacetime
• Strong Chaos of Fast Scrambling Yields Order: Emergence of Decoupled Quantum Information Capsules
• Quantum entanglement of Hawking-Partner modes in expanding cavities
• Vacuum-purified Hawking radiation from evaporating black holes: Lessons from moving mirrors