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The major challenges to fabricate quantum processors and future nano solid state devices are material modification techniques with nanometre resolution and suppression of statistical fluctuations of dopants or qubit carriers. Based on a segmented ion trap with mK laser cooled ions we have realized a deterministic single ion source which could operate with a huge range of sympathetically cooled ion species, isotopes or ionic molecules. We have deterministically extracted a predetermined number of ions on demand and have measured a longitudinal velocity uncertainty of 6.3m/s and a spatial beam divergence of 0.6 mrad. We show in numerical simulations that if the ions are cooled to the motional ground state (Heisenberg limit) nanometre spatial resolution can be achieved.
We consider the precision $Delta varphi$ with which the parameter $varphi$, appearing in the unitary map $U_varphi = e^{ i varphi Lambda}$ acting on some type of probe system, can be estimated when there is a finite amount of prior information about
To quantify quantum optical coherence requires both the particle- and wave-natures of light. For an ideal laser beam [1,2,3], it can be thought of roughly as the number of photons emitted consecutively into the beam with the same phase. This number,
We provide efficient and intuitive tools for deriving bounds on achievable precision in quantum enhanced metrology based on the geometry of quantum channels and semi-definite programming. We show that when decoherence is taken into account, the maxim
We propose an approach to quantum phase estimation that can attain precision near the Heisenberg limit without requiring single-particle-resolved state detection. We show that the one-axis twisting interaction, well known for generating spin squeezin
The use of quantum resources can provide measurement precision beyond the shot-noise limit (SNL). The task of ab initio optical phase measurement---the estimation of a completely unknown phase---has been experimentally demonstrated with precision bey