Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 42: Quantum Coherence, Quantum Information Systems 2

TT 42.2: Talk

Wednesday, March 13, 2013, 15:15–15:30, H18

Anisotropic rare-earth spin ensemble strongly coupled to a superconducting resonator — •Sebastian Probst¹, Hannes Rotzinger¹, Ivan Protopopov², Stefan Wünsch³, Philipp Jung¹, Markus Jerger¹, Michael Siegel³, Alexey V. Ustinov¹, and Pavel Bushev¹ — ¹Physikalisches Institut, Karlsruher Institut für Technologie, D-76128 Karlsruhe, Germany — ²Institut für Nanotechnologie, Karlsruher Institut für Technologie, D-76021 Karlsruhe, Germany — ³Institut für Mikro- und Nanoelektronische Systeme, Karlsruher Institut für Technologie, D-76189

We report on ESR spectroscopy of an erbium spin ensemble strongly coupled to a superconducting lumped element microwave resonator. Er³⁺ ions are distinct from other spin ensembles due to their optical transitions inside the telecom C-band at 1.54 µ m. This feature makes them most attractive for interfacing optical and microwave photons by using a hybrid quantum architecture [1]. However, in contrast to NV-centers or ruby crystals, rare-earth ions possess a magnetic anisotropy due to the host crystal field. This results in a strong angular dependence of the spin g-factor and of the collective coupling strength with respect to the orientation of the DC magnetic field. We have probed this anisotropy at millikelvin temperatures by performing on-chip ESR spectroscopy. The strong coupling regime with a collective coupling of 36 MHz and 11 MHz linewidth has been reached at a resonator frequency of 4.9 GHz for spin transitions with a g-factor of 1.4.
[1] P. Bushev et al., Phys. Rev. B 84, 06051 (R) (2011)