Coherent optical and spin spectroscopy of nanoscale Pr3+:Y2O3

Abstract

We investigate the potential for optical quantum technologies of Pr 3+ :Y2O3 in the form of monodisperse spherical nanoparticles. We measured optical inhomogeneous lines of 27 GHz, and optical homogeneous linewidths of 108 kHz and 315 kHz in particles of 400 nm and 150 nm average diameters respectively for the 1 D2(0)↔ 3 H4(0) transition at 1.4 K. Furthermore, ground state and 1 D2 excited state hyperfine structures in Y2O3 are here for the first time determined by spectral hole burning and modeled by complete Hamiltonian calculations. Ground-state spin transitions have energies of 5.99 MHz and 10.42 MHz for which we demonstrate spin inhomogeneous linewidths of 42 and 45 kHz respectively. Spin T2 up to 880 µs was obtained for the ±3/2 ↔ ±5/2 transition at 10.42 MHz, a value which exceeds that of bulk Pr 3+ doped crystals so far reported. These promising results confirm nanoscale Pr 3+ :Y2O3 as a very appealing candidate to integrate quantum devices. In particular, we discuss here the possibility of using this material for realizing spin photon interfaces emitting indistinguishable single photons.

Defect Engineering for Quantum Grade Rare-Earth Nanocrystals

“…Nevertheless, we were able to show that europium doped Y 2 O 3 nanoparticles can have optical coherence lifetimes as long as 10 µs at 1.3 K 16,17 , while nuclear spin T 2 can reach up to 8 ms at 5 K 18 . Similar values have been observed in Pr 3+ :Y 2 O 3 nanoparticles 19 . Since these particles can be moreover coupled to high finesse optical fiber cavities 13 , these long coherence lifetimes open a broad range of applications from single ion quantum memories to scalable quantum processors through single photon sources.…”

“…A long-pass filter (590 nm cut-off wavelength) was placed in front of the detector (APD Thorlabs 110 A/M) to reject the excitation light. Optical T 2 values were obtained at 1.4 K by two-pulse photon echo spectroscopy with heterodyne detection 16,17,19 .…”

Emerging rare-earth doped material platforms for quantum nanophotonics

“…Similar results have also been reported in Pr 3+ :Y 2 O 3 nanoparticles [94], obtained by homogeneous precipitation, for optical and spin transitions. Compared to Eu 3+ , Pr 3+ has generally stronger optical transitions and more favorable branching ratios that could be beneficial for coupling to a cavity.…”

Defect Engineering for Quantum Grade Rare-Earth Nanocrystals

“…In summary, we find a clear correlation between the presence of oxygen in the plasma forming gases and the increase of optical T 2 in the NPs. The enhancement effect, of a factor 3-5, is consistently observed in all ions (Figure 4(d)), and also for different batches of NPs (Figure 5) 17,19 . In parallel, the MW oxygen plasma treatment induces a broadening of the optical inhomogeneous line, indicating and increased number of point defects.…”

“…We note that the maximum T 2 obtained here is longer than that observed in 5 µm size particles containing 60 nm nanocrystals synthesized by solvothermal method (T 2 = 3.7 µs) 29 , and it is comparable to values reported in 400 nm size NPs (T 2 = 7 µs) 16 and some bulk single crystals 28 . In addition, the enhancement effect is not limited to these particular NPs as optical T 2 enhancement by oxygen plasma has also been recently observed in chemically etched Eu 3+ :Y 2 O 3 NPs 17 as well as Pr 3+ :Y 2 O 3 NPs of different sizes 19 .…”