17,695 research outputs found
Fermionic entanglement ambiguity in non-inertial frames
We analyse an ambiguity in previous works on entanglement of fermionic fields
in non-inertial frames. This ambiguity, related to the anticommutation
properties of field operators, leads to non-unique results when computing
entanglement measures for the same state. We show that the ambiguity disappears
when we introduce detectors, which are in any case necessary as a means to
probe the field entanglement.Comment: 9 pages, 4 figures. Revtex 4.1, added Journal referenc
Redistribution of particle and anti-particle entanglement in non-inertial frames
We analyse the entanglement tradeoff between particle and anti-particle modes
of a Dirac field from the perspective of inertial and uniformly accelerated
observers. Our results show that a redistribution of entanglement between
particle and anti-particle modes plays a key role in the survival of fermionic
field entanglement in the infinite acceleration limit.Comment: 10 pages, 5 figures, revtex4. Added journal referenc
Spin and occupation number entanglement of Dirac fields for non-inertial observers
We investigate the Unruh effect on entanglement taking into account the spin
degree of freedom of the Dirac field. We analyze spin Bell states in this
setting, obtaining their entanglement dependance on the acceleration of one of
the partners. Then, we consider simple analogs to the occupation number
entangled state |00>+|11>, but with spin quantum numbers for |11> showing that,
despite their apparent similitude, while the spinless case is always qubit x
qubit, for the spin case acceleration produces a qubit x qu4it state. We also
introduce a procedure to consistently erase the spin information from our
setting preserving occupation numbers. We show how the maximally entangled
state for occupation number emerges from our setting, we also analyze its
entanglement dependance on acceleration, obtaining a greater entanglement
degradation than in the spinless case.Comment: RevTex, 11 pages, 3 figures. The replacement is due to some minor
misprints correction
Simulating accelerated atoms coupled to a quantum field
We show an analogy between static quantum emitters coupled to a single mode
of a quantum field and accelerated Unruh-DeWitt detectors. We envision a way to
simulate a variety of relativistic quantum field settings beyond the reach of
current computational power, such as high number of qubits coupled to a quantum
field following arbitrary non-inertial trajectories. Our scheme may be
implemented with trapped ions and circuit QED set-ups.Comment: 5 pages, 2 figures, revtex 4-
Residual entanglement of accelerated fermions is not nonlocal
We analyze the operational meaning of the residual entanglement in
non-inertial fermionic systems in terms of the achievable violation of the
Clauser-Horne-Shimony-Holt (CHSH) inequality. We demonstrate that the quantum
correlations of fermions, which were previously found to survive in the
infinite acceleration limit, cannot be considered to be non-local. The
entanglement shared by an inertial and an accelerated observer cannot be
utilized for the violation of the CHSH inequality in case of high
accelerations. Our results are shown to extend beyond the single mode
approximation commonly used in the literature.Comment: 5 pages, 3 figures; v2: minor changes, reference and section headers
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Towards a robotic personal trainer for the elderly
The use of robots in the environment of the elderly has grown significantly in recent years. The idea is to try to increase the comfort and well-being of older people through the employment of some kind of automated processes that simplify daily work. In this paper we present a prototype of a personal robotic trainer which, together with a non-invasive sensor, allows caregivers to monitor certain physical activities in order to improve their performance. In addition, the proposed system also takes into account how the person feels during the performance of the physical exercises and thus, determine more precisely if the exercise is appropriate or not for a specific person.This work was partly supported by the Spanish Government (RTI2018-095390-B-C31) and FCT—Fundação para a Ciência e Tecnologia through the Post-Docscholarship SFRH/BPD/102696/2014 (A. Costa) and UID/CEC/00319/2019
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