Abstract
In this review we discuss how channel simulation can be used to simplify the most general protocols of quantum parameter estimation, where unlimited entanglement and adaptive joint operations may be employed. Whenever the unknown parameter encoded in a quantum channels is completely transferred in an environmental program state simulating the channel, the optimal adaptive estimation cannot beat the standard quantum limit. In this setting, we elucidate the crucial role of quantum teleportation as a primitive operation which allows one to completely reduce adaptive protocols over suitable teleportation-covariant channels and derive matching upper and lower bounds for parameter estimation. For these channels, we may express the quantum Cramer Rao bound directly in terms of their Choi matrices. Our review considers both discrete- and continuous-variable systems, also presenting some new results for bosonic Gaussian channels using an alternative sub-optimal simulation. It is an open problem to design simulations for quantum channels that achieve the Heisenberg limit.
| Original language | English |
|---|---|
| Number of pages | 13 |
| Journal | Quantum Measurements and Quantum Metrology |
| Volume | 5 |
| Issue number | 1 |
| Early online date | 4 Apr 2018 |
| DOIs | |
| Publication status | E-pub ahead of print - 4 Apr 2018 |
Bibliographical note
© 2018, The Author(s). Short review paper. REVTeX 10 pages. 6 figuresKeywords
- quant-ph
- cond-mat.other
- physics.optics