Rare-earth spin ensemble to interface microwave and optical photons
Dr. Pavel Bushev (Physikalisches Institut, Karlsruher Institut für Technologie, D-76131 Karlsruhe)

Interfacing superconducting quantum processors, working in GHz frequency range, with optical quantum networks and atomic qubits is a challenging task for the implementation of the distributed quantum information processing as well as for the quantum communication . Spin ensembles of Kramers rare-earth ions provide excellent properties to bridge microwave and optical domains at the quantum level. Other possible spin ensembles include: NV-centers in diamond [1-3], organic molecules [4], chromium ions in ruby [2], fullerene cages and P-donors in silicon [5]. Among the other spin ensembles, Er 3+ ion stands out because of it is a magnetic ion with optical transitions at telecom C-band at 1.55 µm.

I will present experiment on a magnetic coupling of the Er 3+ spins doped in Y2SiO5 crystal to a different high-Q coplanar superconducting as well as normal metal resonator [6]. The measured coupling strength for electronic transition ranges between 5 and 22 MHz and for hyperfine states is about 1-3 MHz. The presented experiments realize the first step towards implementation of a solid-state based quantum memory with telecom wavelength conversion which can constitute the essential building blocks of the quantum internet.

References:

[1] Y. Kubo et al., Phys. Rev. Lett. 107, 220501 (2011),
[2] D. I.Shuster et al., Phys. Rev. Lett. 105, 140501 (2010),
[3] R. Amsüss et al., Phys. Rev. Lett. 107, 060502 (2011),
[4] I. Chiorescu et al., Phys. Rev.B 82, 024413 (2010),
[5] H. Wu et al., Phys. Rev. Lett. 105, 140503 (2010),
[6] P. Bushev et al., Phys. Rev. B 84, 060501(R) (2011).