7 research outputs found
Anomalous Purcell decay of strongly driven inhomogeneous emitters coupled to a cavity
We perform resonant fluorescence lifetime measurements on a
nanocavity-coupled erbium ensemble as a function of cavity-laser detuning and
pump power. Our measurements reveal an anomalous suppression of the ensemble
decay lifetime at zero cavity detuning and high pump fluence. We capture
qualitative aspects of this decay rate suppression using a Tavis-Cummings model
of non-interacting spins coupled to a common cavity.Comment: 4 figure
Purcell enhancement of erbium ions in TiO on silicon nanocavities
Isolated solid-state atomic defects with telecom optical transitions are
ideal quantum photon emitters and spin qubits for applications in long-distance
quantum communication networks. Prototypical telecom defects such as erbium
suffer from poor photon emission rates, requiring photonic enhancement using
resonant optical cavities. Many of the traditional hosts for erbium ions are
not amenable to direct incorporation with existing integrated photonics
platforms, limiting scalable fabrication of qubit-based devices. Here we
present a scalable approach towards CMOS-compatible telecom qubits by using
erbium-doped titanium dioxide thin films grown atop silicon-on-insulator
substrates. From this heterostructure, we have fabricated one-dimensional
photonic crystal cavities demonstrating quality factors in excess of
and corresponding Purcell-enhanced optical emission rates of
the erbium ensembles in excess of 200. This easily fabricated materials
platform represents an important step towards realizing telecom quantum
memories in a scalable qubit architecture compatible with mature silicon
technologies.Comment: 3 figure
Nanocavity-mediated Purcell enhancement of Er in TiO thin films grown via atomic layer deposition
The use of trivalent erbium (Er), typically embedded as an atomic
defect in the solid-state, has widespread adoption as a dopant in
telecommunications devices and shows promise as a spin-based quantum memory for
quantum communication. In particular, its natural telecom C-band optical
transition and spin-photon interface makes it an ideal candidate for
integration into existing optical fiber networks without the need for quantum
frequency conversion. However, successful scaling requires a host material with
few intrinsic nuclear spins, compatibility with semiconductor foundry
processes, and straightforward integration with silicon photonics. Here, we
present Er-doped titanium dioxide (TiO) thin film growth on silicon
substrates using a foundry-scalable atomic layer deposition process with a wide
range of doping control over the Er concentration. Even though the as-grown
films are amorphous, after oxygen annealing they exhibit relatively large
crystalline grains, and the embedded Er ions exhibit the characteristic optical
emission spectrum from anatase TiO. Critically, this growth and annealing
process maintains the low surface roughness required for nanophotonic
integration. Finally, we interface Er ensembles with high quality factor Si
nanophotonic cavities via evanescent coupling and demonstrate a large Purcell
enhancement (300) of their optical lifetime. Our findings demonstrate a
low-temperature, non-destructive, and substrate-independent process for
integrating Er-doped materials with silicon photonics. At high doping densities
this platform can enable integrated photonic components such as on-chip
amplifiers and lasers, while dilute concentrations can realize single ion
quantum memories.Comment: 5 figure
Optical and microstructural characterization of Er doped epitaxial cerium oxide on silicon
Rare-earth ion dopants in solid-state hosts are ideal candidates for quantum
communication technologies such as quantum memory, due to the intrinsic
spin-photon interface of the rare-earth ion combined with the integration
methods available in the solid-state. Erbium-doped cerium oxide (Er:CeO) is
a particularly promising platform for such a quantum memory, as it combines the
telecom-wavelength (~1.5 m) 4f-4f transition of erbium, a predicted long
electron spin coherence time supported by CeO, and is also near
lattice-matched to silicon for heteroepitaxial growth. In this work, we report
on the epitaxial growth of Er:CeO thin films on silicon using molecular
beam epitaxy (MBE), with controlled erbium concentration down to 2 parts per
million (ppm). We carry out a detailed microstructural study to verify the
CeO host structure, and characterize the spin and optical properties of the
embedded Er ions. In the 2-3 ppm Er regime, we identify EPR linewidths
of 245(1) MHz, optical inhomogeneous linewidths of 9.5(2) GHz, optical excited
state lifetimes of 3.5(1) ms, and spectral diffusion-limited homogenoeus
linewidths as narrow as 4.8(3) MHz in the as-grown material. We test annealing
of the Er:CeO films up to 900 deg C, which yields modest narrowing of the
inhomogeneous linewidth by 20% and extension of the excited state lifetime by
40%. We have also studied the variation of the optical properties as a function
of Er doping and find that the results are consistent with the trends expected
from inter-dopant charge interactions.Comment: 15 pages, 6 figures (including supplemental information
Optical and microstructural characterization of Er3+ doped epitaxial cerium oxide on silicon
Rare-earth ion dopants in solid-state hosts are ideal candidates for quantum communication technologies, such as quantum memories, due to the intrinsic spin–photon interface of the rare-earth ion combined with the integration methods available in the solid state. Erbium-doped cerium oxide (Er:CeO2) is a particularly promising host material platform for such a quantum memory, as it combines the telecom-wavelength (∼1.5μm) 4f–4f transition of erbium, a predicted long electron spin coherence time when embedded in CeO2, and a small lattice mismatch with silicon. In this work, we report on the epitaxial growth of Er:CeO2 thin films on silicon using molecular beam epitaxy, with controlled erbium concentration between 2 and 130 parts per million (ppm). We carry out a detailed microstructural study to verify the CeO2 host structure and characterize the spin and optical properties of the embedded Er3+ ions as a function of doping density. In as-grown Er:CeO2 in the 2–3 ppm regime, we identify an EPR linewidth of 245(1) MHz, an optical inhomogeneous linewidth of 9.5(2) GHz, an optical excited state lifetime of 3.5(1) ms, and a spectral diffusion-limited homogeneous linewidth as narrow as 4.8(3) MHz. We test the annealing of Er:CeO2 films up to 900 °C, which yields narrowing of the inhomogeneous linewidth by 20% and extension of the excited state lifetime by 40%