Optical study of the anisotropic erbium spin flip-flop dynamics

Abstract

We investigate the erbium flip-flop dynamics as a limiting factor of the electron spin lifetime and more generally as an indirect source of decoherence in rare-earth doped insulators. Despite the random isotropic arrangement of dopants in the host crystal, the dipolar interaction strongly depends on the magnetic field orientation following the strong anisotropy of the g-factor. In Er 3+ :Y2SiO5, we observe by transient optical spectroscopy a three orders of magnitude variation of the erbium flipflop rate (10ppm dopant concentration). The measurements in two different samples, with 10ppm and 50ppm concentrations, are well-supported by our analytic modeling of the dipolar coupling between identical spins with an anisotropic g-tensor. The model can be applied to other rare-earth doped materials. We extrapolate the calculation to Er 3+ :CaWO4, Er 3+ :LiNbO3 and Nd 3+ :Y2SiO5 at different concentrations.

Coherent Control in the Ground and Optically Excited States of an Ensemble of Erbium Dopants

“…Measuring the decay of the antihole over time (inset), allows us to determine the lifetime of the optical and spin transition. We find a value of 53(3) ms for the latter, limited by flip-flop interactions (as observed and characterized recently under similar conditions [21]). The groundstate lifetime is thus considerably longer than that of the excited state, 11 ms [22].…”

“…As observed earlier, even at low concentrations the lifetime of their spin state is limited by flip-flop interactions [5], with a strong dependence on the magnetic field orientation [21] that originates from the anisotropic Zeeman Hamiltonian [20]. As the lifetime improves quadratically with the dopant concentration, we use crystals with a comparably low erbium concentration of 10 ppm, which reduces to ∼ 2 ppm per site and class for the even isotopes.…”

“…Second, the initialization can be very quick, typically ∼ 1 µs, as it is only limited by the optical Rabi frequency. Therefore, this scheme can be applied even at elevated temperature, or in highly-doped crystals in which the flip-flop dominated ground-state spin relaxation is much faster than spontaneous decay from the excited state [21], such that optical pumping is not possible.…”

Optical quantum nondemolition measurement of a single rare earth ion qubit

“…4b) 28 . One possible explanation is flip-flop interactions with nearby Er 3+ ions 33 , which is consistent with the fact that T 1,dark varies sharply with the magnetic field angle and is different by a factor of 20 between three ions studied (Supplementary Note 6). In this device, the average separation between magnetically equivalent Er 3+ ions is estimated to be 70 nm, such that the dipole-dipole interaction strength is around 1 kHz; the flip-flop rate is likely much slower because of spectral diffusion from nearby 89 Y nuclear spins.…”

Dynamical Decoupling of Spin Ensembles with Strong Anisotropic Interactions

“…in the context of sensing [23]. In this work, we characterize this improvement for anisotropic ensembles using erbium-doped yttrium-orthosilicate (Er:YSO), which is known to exhibit particularly strong spin-spin interactions [24] caused by the large effective g-factor of the erbium spins [25].…”