### Quantum Metrology beyond the Classical Limit under the Effect of Dephasing

2018.04.04

Yuichiro Matsuzaki, NTT Basic Research Laboratories

Quantum magnetic field sensors are expected to have many applications in the fields of biology and material science. It is well known that classical sensors typically have a sensitivity scaling law of order δB=O(1/T0.5) whereδB is the uncertainty in the fields estimation while T is the total measurement time. Quantum sensors on the other hand can in principle provide us with a better uncertainty scaling asδB=O(1/T). However, as qubit’s are fragile to dephasing noise it has been believed that such quantum scaling’s cannot be achieved under in realistic environments. Here we propose a novel way to achieve this magnetic field sensor quantum scaling using qubit quantum teleportation. It is known that any interaction between a qubit and environment induces unwanted correlations between them which in turn decreases the coherence of the qubit and hence it’s sensitivity. Quantum teleportation can however suppress the generation of such correlations protecting the qubits from these dephasing effects. Our approach could provide a practical quantum sensor with sensitivity far beyond than that of their classical counterparts.

Y. Matsuzaki, and et al, arXiv:1708.01395, accepted by Physical Review Letters

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