Publications Repository - Gdańsk University of Technology

Quantum entanglement may provide a huge boost in the precision of parameter estimation. However, quantum metrology seems to be extremely sensitive to noise in the probe state. There is an important still open question: What type of entanglement is useful as a resource in quantum metrology? Here we raise this question in relation to entanglement distillation. We provide a counterintuitive example of a family of bound entangled states which can be used in quantum enhanced metrology with the precision advantage approaching the Heisenberg limit. This shows that so-called distillability is not necessary for quantum advantage inmetrology. Surprisingly, entanglement of the applied states is very weak, which is reflected by the lack of the so-called unlockability property. Moreover we find instances where quantum Fisher information reports the presence of entanglement where a well-known class of nonlinear entanglement witnesses (stronger than multisetting correlation Bell inequalities) does not. We have thus provided strong evidence that quantum metrology can be treated as additional operational face of multipartite entanglement, independent of two other basic operational features used in quantum information theory: nonlocality and distillability.

Authors

• Ł. Czekaj,
• A. Przysiężna,
• M. Horodecki,
• prof. dr hab. Paweł Horodecki link open in new tab