2307/2307.00916.md

Title: Enhanced Spectral Density of a Single Germanium Vacancy Center in a Nanodiamond by Cavity-Integration

URL Source: https://arxiv.org/html/2307.00916

Published Time: Fri, 01 Dec 2023 02:01:16 GMT

Markdown Content: Corresponding author: ]alexander.kubanek@uni-ulm.de

Florian Feuchtmayr F.F. and R.B. contributed equally to this work. Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Robert Berghaus F.F. and R.B. contributed equally to this work. Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Selene Sachero Gregor Bayer Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Niklas Lettner Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Center for Integrated Quantum Science and Technology (IQst), Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Richard Waltrich Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Patrick Maier Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Viatcheslav Agafonov GREMAN, UMR 7347 CNRS, INSA-CVL, Tours University, 37200 Tours, France Alexander Kubanek [ Institute for Quantum Optics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Center for Integrated Quantum Science and Technology (IQst), Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany

(November 30, 2023)

††preprint: AIP/123-QED I Debye-Waller factor

In order to determine the DW factor, the counts of the ZPL and the counts of the PSB were added up separately up to a wavelength of 700 nm. Comparing these counts with

DW=ZPL ZPL+PSB DW ZPL ZPL PSB\text{DW}=\frac{\text{ZPL}}{\text{ZPL}+\text{PSB}}DW = divide start_ARG ZPL end_ARG start_ARG ZPL + PSB end_ARG(S1)

yielded a DW factor of 0.6. On the other hand, the DW factor was calculated to 0.7 by integrating the fits of the ZPL and PSB as seen in fig. S1. Therefore, 0.6 is given in the main manuscript as a lower bound.

Figure S1: Magnified PL spectrum of fig. 1(c) of the main manuscript with a coarse grating of 150 g/mm of ND GeV-I. The ZPL and PSB are fitted with Lorentzian functions. Orange fit shows the sum of the two functions.

II Autocorrelation Measurements

The sample from which ND GeV-I was taken also contained further NDs with single defects e.g. ND GeV-II and ND GeV-III. Their autocorrelation measurements under off-resonant excitation are depicted in figure S2 and show antibunching. It can be concluded that the emission of these NDs is dominated by single GeV−{}^{-}start_FLOATSUPERSCRIPT - end_FLOATSUPERSCRIPT centers with lifetimes ranging between τ=1.3− 5.8 𝜏 1.3 5.8\tau=1.3,-,5.8 italic_τ = 1.3 - 5.8 ns.

Figure S2: Off-resonant autocorrelation measurements without background correction. (a) ND GeV-II showing anti-bunching of g(2)⁢(0)superscript 𝑔 2 0 g^{(2)}(0)italic_g start_POSTSUPERSCRIPT ( 2 ) end_POSTSUPERSCRIPT ( 0 )=0.11 ±plus-or-minus\pm± 0.07 and an excited state lifetime of τ LT subscript 𝜏 LT\tau_{\textup{LT}}italic_τ start_POSTSUBSCRIPT LT end_POSTSUBSCRIPT=(5.8 ±plus-or-minus\pm± 0.9) ns at (75 ±plus-or-minus\pm± 3) μ μ\upmu roman_μ W. (b) ND GeV-III showing anti-bunching of g(2)⁢(0)superscript 𝑔 2 0 g^{(2)}(0)italic_g start_POSTSUPERSCRIPT ( 2 ) end_POSTSUPERSCRIPT ( 0 )=0.34 ±plus-or-minus\pm± 0.03 and an excited state lifetime of τ LT subscript 𝜏 LT\tau_{\textup{LT}}italic_τ start_POSTSUBSCRIPT LT end_POSTSUBSCRIPT=(1.28 ±plus-or-minus\pm± 0.09) ns at (42 ±plus-or-minus\pm± 2) μ μ\upmu roman_μ W.

III Nanomanipulation of Nanodiamonds

The employed pick and place technique used here is comparable to earlier works: Fehler et al. Fehler et al. (2021) transfer of a SiV-ND to a photonic crystal cavity) and Bayer et al. Bayer et al. (2022) transfer of a SiV-ND to a focused ion beam milled cavity structure).

To scan and identify the NDs before the transfer we used a platinum cantilever (tip: HQ:NSC15/Pt). The selected ND could be picked up using contact mode. Having the ND attached to the cantilever and the upper mirror mount with the CO 2 2{}_{2}start_FLOATSUBSCRIPT 2 end_FLOATSUBSCRIPT fabricated cavity structures mounted inside the AFM the structures could be located by scanning in contactless tapping mode. From this imaging the center of the cavity structure could be identified, where the ND was then placed. For a more precise (AFM resolution) positioning of the ND contact nanomanipulation was used to push the ND with a low-adhesion cantilever (tip: 160AC-NA). AFM nanomanipulation of the ND was performed with the help of the JPK nanomanipulation toolbox.

With a ND centered in the cavity mirror we then align our optical cavity on a maximized TEM00 mode in order to overlap the positioned ND with the cavity field.

The presented universal cavity integration can be carried out for other ND and other nanoparticles from different fabrication methods. Advancements in the production methods, such as employing ND growth under lower growth temperatures,Alkahtani et al. (2019) or ion implantation Xu et al. (2023) could enable small (sub- 50 nm) NDs containing single, spectral stable GeV−{}^{-}start_FLOATSUPERSCRIPT - end_FLOATSUPERSCRIPT center in the future. Therewith, the finesse could be increased significantly.

IV Spectral Enhancement Calculations

Table S1: SDE calculations of ND GeV-I including different setup efficiencies. For better comparison the enhancements are calculated in respect to the free space emitter.

We analyzed the spectra of ND GeV-I in figures 1(d), 2(f) and 3(d) of the main manuscript, which were acquired in confocal microscope setups I, II and the cavity setup, respectively. The SDs of each spectrum were extracted and the total excitation and detection efficiencies (η exc superscript 𝜂 exc\eta^{\textup{exc}}italic_η start_POSTSUPERSCRIPT exc end_POSTSUPERSCRIPT, η det superscript 𝜂 det\eta^{\textup{det}}italic_η start_POSTSUPERSCRIPT det end_POSTSUPERSCRIPT) of each setup were determined, see table S1. From these values, the SDE with respect to Confocal I is given by

SDE=SD SD Con1×η Con1 det η det×η Con1 exc η exc.SDE SD subscript SD Con1 superscript subscript 𝜂 Con1 det superscript 𝜂 det superscript subscript 𝜂 Con1 exc superscript 𝜂 exc\textup{SDE}=\frac{\textup{SD}}{\textup{SD}{\textup{Con1}}}\times\frac{\eta{% \textup{Con1}}^{\textup{det}}}{\eta^{\textup{det}}}\times\frac{\eta_{\textup{% Con1}}^{\textup{exc}}}{\eta^{\textup{exc}}}.SDE = divide start_ARG SD end_ARG start_ARG SD start_POSTSUBSCRIPT Con1 end_POSTSUBSCRIPT end_ARG × divide start_ARG italic_η start_POSTSUBSCRIPT Con1 end_POSTSUBSCRIPT start_POSTSUPERSCRIPT det end_POSTSUPERSCRIPT end_ARG start_ARG italic_η start_POSTSUPERSCRIPT det end_POSTSUPERSCRIPT end_ARG × divide start_ARG italic_η start_POSTSUBSCRIPT Con1 end_POSTSUBSCRIPT start_POSTSUPERSCRIPT exc end_POSTSUPERSCRIPT end_ARG start_ARG italic_η start_POSTSUPERSCRIPT exc end_POSTSUPERSCRIPT end_ARG .(S2)

For the SD, the FWHM at the confocal configurations were obtained by the Lorentzian fit of the ZPL. The FWHM of the cavity configuration was given by FWHM = FSR / ℱ ℱ\mathcal{F}caligraphic_F with FSR = c / 2L and ℱ ℱ\mathcal{F}caligraphic_F at the emitter.

The total excitation efficiency includes the ratio of the emitter area and the beam area, the relative efficiency of different excitation wavelengths Häußler et al. (2017) and the effective excitation power by weighting the finesse. The detection efficiency takes the transmission of every optical component of the three different setups into account.

References

References

• Fehler et al. (2021)K.G.Fehler, L.Antoniuk, N.Lettner, A.P.Ovvyan, R.Waltrich, N.Gruhler, V.A.Davydov, V.N.Agafonov, W.H.P.Pernice, and A.Kubanek,“Hybrid quantum photonics based on artificial atoms placed inside one hole of a photonic crystal cavity,”ACS Photonics 8,2635–2641 (2021).
• Bayer et al. (2022)G.Bayer, R.Berghaus, S.Sachero, A.B.Filipovski, L.Antoniuk, N.Lettner, R.Waltrich, M.Klotz, P.Maier, V.Agafonov, and A.Kubanek,“A quantum repeater platform based on single siv−{}^{-}start_FLOATSUPERSCRIPT - end_FLOATSUPERSCRIPT centers in diamond with cavity-assisted, all-optical spin access and fast coherent driving,”arXiv (2022).
• Alkahtani et al. (2019)M.Alkahtani, J.Lang, B.Naydenov, F.Jelezko, and P.Hemmer,“Growth of high-purity low-strain fluorescent nanodiamonds,”ACS Photonics 6,1266–1271 (2019),https://doi.org/10.1021/acsphotonics.9b00224 .
• Xu et al. (2023)X.Xu, Z.O.Martin, M.Titze, Y.Wang, D.Sychev, J.Henshaw, A.S.Lagutchev, H.Htoon, E.S.Bielejec, S.I.Bogdanov, V.M.Shalaev, and A.Boltasseva,“Fabrication of single color centers in sub-50 nm nanodiamonds using ion implantation,”Nanophotonics 12,485–494 (2023).
• Häußler et al. (2017)S.Häußler, G.Thiering, A.Dietrich, N.Waasem, T.Teraji, J.Isoya, T.Iwasaki, M.Hatano, F.Jelezko, A.Gali, et al.,“Photoluminescence excitation spectroscopy of siv- and gev- color center in diamond,”New Journal of Physics 19,063036 (2017).