Research ArticleAPPLIED PHYSICS

Long-term data storage in diamond

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Science Advances  26 Oct 2016:
Vol. 2, no. 10, e1600911
DOI: 10.1126/sciadv.1600911
  • Fig. 1 Charge manipulation and readout in diamond.

    (A) Energy diagram for NV and NV0. In (1) and (2), the successive absorption of two photons (wavy arrows) of energy equal or greater than 1.95 eV (637 nm) propels the excess electron of an NV into the conduction band, leaving the defect in the neutral ground state (solid arrows). In (3) and (4), an NV0 consecutively absorbs two photons of energy equal or greater than 2.16 eV (575 nm) transforming into NV. CB, conduction band; VB, valence bands. (B) Top: A binary pattern on an NV-rich background is imprinted via spatially selective red illumination (632 nm, 350 μW, 100 ms per pixel). Bottom: Starting from an NV-depleted background, the pattern results from selective illumination with green laser light (532 nm, 30 μW, 5 ms per pixel). From left to right, images are the result of three successive readouts of the same original imprint via a red scan (200 and 150 μW for the upper and lower rows, respectively). In all cases, the image size is 100 × 100 pixels, and the integration time is 1 ms per pixel. kcps, kilocounts/s.

  • Fig. 2 Diamond as a 3D read/write memory.

    (A) Starting from a blank ensemble of NV centers (1), information can be written (2), erased (3), and rewritten (4). In (1) and (3), a green laser scan (1 mW at 1 ms per pixel) was used to reset the target plane to a bright state. In (2) and (4), images were imprinted via a red laser scan with a variable exposure time per pixel (from 0 to 50 ms). Note the gray scale in the resulting images corresponding to multivalued (as opposed to binary) encoding. The same scale bar applies to all four images. (B) Information can be stored and accessed in three dimensions, as demonstrated for the case of a three-level stack. Observations over a period of a week show no noticeable change in these patterns for a sample kept in the dark. In (A) and (B), readout is carried out via a red laser scan (200 μW at 1 ms per pixel). The image size is 150 × 150 pixels in all cases.

  • Fig. 3 Combined NV charge and spin manipulation.

    (A) Charge-conditional initialization of the 14N nuclear spin host into mI = 0 is attained via spin transfer from the optically polarized NV electronic spin (see also figs. S4 and S5). Initialization into NV (NV0) is attained by applying (or not) a green laser pulse (532 nm, 1 mW, 10 μs) on an NV-depleted background (632 nm, 250 μW, 50 ms per pixel). Following 14N polarization, (unconditional) reconversion into NV is attained via a green laser pulse (532 nm, 1 mW, 3 μs). The durations of the MW and RF pulses are 440 ns and 28 μs, respectively. (B) Measured NV ODMR spectra after the application of the pulse sequence in (A). The upper images (632 nm, 250 μW, 1 ms per pixel) show the NV fluorescence in a vicinity of the probed sample spot (coincident with the image center) after charge initialization. (C) With the 14N spin in the mI = 0 state, negatively charged NVs undergo a cycle of ionization and recharge. The pulse protocol is identical to that in (A) except that a blue laser pulse (450 nm, 400 μW, 30 μs) is introduced after nuclear spin polarization, temporarily converting NV into NV0, as indicated by the upper fluorescence images. Comparison of the ODMR spectra before (left) and after (right) the application of the ionization/recharge cycle nearly shows no change of the 14N spin polarization. In (B) and (C), every point in the ODMR spectra corresponds to 105 consecutive averages; solid lines are Lorentzian fits to the three 14N hyperfine peaks; P denotes the fractional area under the central peak. a.u., arbitrary units.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/10/e1600911/DC1

    section S1. Charge-conditioned polarization of the 14N spin.

    section S2. Impact of NV ionization and recharge on the 14N spin polarization.

    fig. S1. Spatial resolution of NV charge patterning.

    fig. S2. Impact of multiple readouts on NV fluorescence contrast.

    fig. S3. NV response upon multiple read/write cycles.

    fig. S4. Impact of NV ionization on the 14N nuclear spin polarization.

    fig. S5. Impact of NV recharge on the 14N nuclear spin polarization.

  • Supplementary Materials

    This PDF file includes:

    • section S1. Charge-conditioned polarization of the 14N spin.
    • section S2. Impact of NV ionization and recharge on the 14N spin polarization.
    • fig. S1. Spatial resolution of NV charge patterning.
    • fig. S2. Impact of multiple readouts on NV fluorescence contrast.
    • fig. S3. NV response upon multiple read/write cycles.
    • fig. S4. Impact of NV ionization on the 14N nuclear spin polarization.
    • fig. S5. Impact of NV recharge on the 14N nuclear spin polarization.

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