Surpassing the thermal Cramér-Rao bound with collisional thermometry

  title={Surpassing the thermal Cram{\'e}r-Rao bound with collisional thermometry},
  author={Angeline Shu and Stella Seah and Valerio Scarani},
  journal={arXiv: Quantum Physics},
In collisional thermometry, a system in contact with the thermal bath is probed by a stream of ancillas. Coherences and collective measurements were shown to improve the Fisher information in some parameter regimes, for a stream of independent and identically prepared (i.i.d.) ancillas in some specific states [Seah et al., Phys. Rev. Lett., 180602 (2019)]. Here we refine the analysis of this metrological advantage by optimising over the possible input ancilla states, also for block-i.i.d… 

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