State-merging

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In quantum information theory, quantum state merging [1] [2] is the transfer of a quantum state when the receiver already has part of the state. The process optimally transfers partial information using entanglement and classical communication. It allows for sending information using an amount of entanglement given by the conditional quantum entropy, with the Von Neumann entropy, . It thus provides an operational meaning to this quantity.

Unlike its classical counterpart, the quantum conditional entropy can be negative. In this case, the sender can transfer the state to the receiver using no entanglement, and as an added bonus, this amount of entanglement can be gained, rather than used. Thus quantum information can be negative.

The amount of classical information needed is the mutual information . The case where the classical communication is replaced by quantum communication was considered in. [3] This is known as the Fully Quantum Slepian-Wolf Theorem, since everything is sent down the quantum channel. A single-shot version of state merging was found by Berta, [4] and a multiparty single shot version was found in. [5] The quantum discord has been interpreted using state merging. [6]

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In quantum information theory, the reduction criterion is a necessary condition a mixed state must satisfy in order for it to be separable. In other words, the reduction criterion is a separability criterion. It was first proved and independently formulated in 1999. Violation of the reduction criterion is closely related to the distillability of the state in question.

In the case of systems composed of subsystems, the classification of quantum-entangledstates is richer than in the bipartite case. Indeed, in multipartite entanglement apart from fully separable states and fully entangled states, there also exists the notion of partially separable states.

In quantum information science, the concurrence is a state invariant involving qubits.

Michał Horodecki is a Polish physicist at the University of Gdańsk working in the field of quantum information theory, notable for his work on entanglement theory.

In quantum information theory, quantum discord is a measure of nonclassical correlations between two subsystems of a quantum system. It includes correlations that are due to quantum physical effects but do not necessarily involve quantum entanglement.

The noisy-storage model refers to a cryptographic model employed in quantum cryptography. It assumes that the quantum memory device of an attacker (adversary) trying to break the protocol is imperfect (noisy). The main goal of this model is to enable the secure implementation of two-party cryptographic primitives, such as bit commitment, oblivious transfer and secure identification.

In quantum mechanics, negativity is a measure of quantum entanglement which is easy to compute. It is a measure deriving from the PPT criterion for separability. It has shown to be an entanglement monotone and hence a proper measure of entanglement.


In quantum information and quantum computation, an entanglement monotone is a function that quantifies the amount of entanglement present in a quantum state. Any entanglement monotone is a nonnegative function whose value does not increase under local operations and classical communication.

References

  1. Horodecki, M.; Oppenheim, J.; Winter, A. (2005). "Partial quantum information". Nature. 436 (7051): 673–676. arXiv: quant-ph/0505062 . Bibcode:2005Natur.436..673H. doi:10.1038/nature03909. PMID   16079840. S2CID   4413693.
  2. Horodecki, M.; Oppenheim, J.; Winter, A. (2007). "Quantum state merging and negative information". Communications in Mathematical Physics. 269 (1): 107–136. arXiv: quant-ph/0512247 . Bibcode:2007CMaPh.269..107H. doi:10.1007/s00220-006-0118-x. S2CID   119421959.
  3. Abeyesinghe, A.; Devetak, I.; Hayden, P; Winter, A. (2009). "The mother of all protocols: restructuring quantum information's family tree". Proc. R. Soc. A. 465 (2108): 2537–2563. arXiv: quant-ph/0606225 . Bibcode:2009RSPSA.465.2537A. doi:10.1098/rspa.2009.0202. S2CID   44021187.
  4. Berta, M. (2009). "Single-shot quantum state merging". arXiv: 0912.4495 [quant-ph].
  5. Dutil, N.; Hayden, P. (2010). "One-shot Multiparty State Merging". arXiv: 1011.1974 [quant-ph].
  6. Madhok, V.; Datta, A. (2011). "Interpreting quantum discord through quantum state merging". Physical Review A. 83 (3): 032323. arXiv: 1008.4135 . Bibcode:2011PhRvA..83c2323M. doi:10.1103/PhysRevA.83.032323. S2CID   10898479.