Bound entanglement, in contrast to free entanglement, cannot be distilled into maximally entangled states by two local observers applying measurements and utilizing classical communication. In this paper we ask whether a relativistic observer classifies states according to being separable, bound or free entangled in the same manner as an unboosted observer. Surprisingly, this turns out not to be the case. And that even if the system in a given inertial frame of reference is separable with respect to the partition momenta versus spins. In detail, we show that if the spin state is initially bound entangled, some boosted observers observe their spin states to be either bound entangled, separable or free entangled. This also explains why a general measure of the entanglement property is difficult to find.
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http://dx.doi.org/10.1038/s41598-023-38217-3 | DOI Listing |
Int J Nurs Stud
January 2025
NIHR Collaboration for Applied Research (Wessex), University of Southampton, Southampton, United Kingdom. Electronic address:
Ongoing challenges in the provision of care, driven by growing care complexity and nursing shortages, prompt us to reconsider the basis for efficient division of nursing labour. In organising nursing work, traditionally the focus has been on identifying nursing tasks that can be delegated to other less expensive and less highly educated staff, in order to make best use of scarce resources. We argue that nursing care activities are connected and intertwined.
View Article and Find Full Text PDFEntropy (Basel)
December 2024
Department of Physics, University of Maryland, College Park, MD 20742-4111, USA.
We define predictive states and predictive complexity for quantum systems composed of distinct subsystems. This complexity is a generalization of entanglement entropy. It is inspired by the statistical or forecasting complexity of predictive state analysis of stochastic and complex systems theory but is intrinsically quantum.
View Article and Find Full Text PDFEntropy (Basel)
November 2024
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China.
Controlled quantum teleportation is an important extension of multipartite quantum teleportation, which plays an indispensable role in building quantum networks. Compared with discrete variable counterparts, continuous variable controlled quantum teleportation can generate entanglement deterministically and exhibit higher superiority of the supervisor's authority. Here, we define a measure to quantify the control power in continuous variable controlled quantum teleportation via Greenberger-Horne-Zeilinger-type entangled coherent state channels.
View Article and Find Full Text PDFNat Commun
January 2025
TCM Group, Cavendish Laboratory, Department of Physics, Cambridge, UK.
We report on a class of gapped projected entangled pair states (PEPS) with non-trivial Euler topology motivated by recent progress in band geometry. In the non-interacting limit, these systems have optimal conditions relating to saturation of quantum geometrical bounds, allowing for parent Hamiltonians whose lowest bands are completely flat and which have the PEPS as unique ground states. Protected by crystalline symmetries, these states evade restrictions on capturing tenfold-way topological features with gapped PEPS.
View Article and Find Full Text PDFSci Rep
December 2024
Departamento de Física, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911, Leganés, Spain.
Considering a universal deep neural network organized as a series of nested qubit rotations, accomplished by adjustable data re-uploads we analyze its expressivity. This ability to approximate continuous functions in regression tasks is quantified making use of a partial Fourier decomposition of the generated output and systematically benchmarked with the aid of a teacher-student scheme. While the maximal expressive power increases with the depth of the network and the number of qubits, it is fundamentally bounded by the data encoding mechanism.
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