Measurement of the Ultrafast Spectral Diffusion of the Optical Transition of Nitrogen Vacancy Centers in Nano-Size Diamond Using Correlation Interferometry

Janik Wolters, Nikola Sadzak, Andreas W. Schell, Tim Schröder, and Oliver Benson

Phys. Rev. Lett. 110, 027401 – Published 9 January 2013

Abstract

Spectral diffusion is the phenomenon of random jumps in the emission wavelength of narrow lines. This phenomenon is a major hurdle for applications of solid state quantum emitters like quantum dots, molecules, or diamond defect centers in an integrated quantum optical technology. Here, we provide further insight into the underlying processes of spectral diffusion of the zero-phonon line of single nitrogen vacancy centers in nano-size diamond by using a novel method based on photon correlation interferometry. The method works although the spectral diffusion rate is several orders of magnitude higher than the photon detection rate and thereby improves the time resolution of previous experiments with nano-size diamond by 6 orders of magnitude. We study the dependency of the spectral diffusion rate on the excitation power, temperature, and excitation wavelength under off-resonant excitation. Our results bring insight into the mechanism of spectral diffusion and suggest a strategy to increase the number of spectrally indistinguishable photons emitted by diamond nanocrystals.

Received 23 May 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.027401

Authors & Affiliations

Janik Wolters^*, Nikola Sadzak, Andreas W. Schell, Tim Schröder, and Oliver Benson

Nano-Optics, Institute of Physics, Humboldt-Universität zu Berlin, Newtonstrasse 15, D-12489 Berlin, Germany

^*janik.wolters@physik.hu-berlin.de

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Vol. 110, Iss. 2 — 11 January 2013

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Images

Figure 1
(a) Toy model for spectral diffusion. Charge traps are ionized and lead to fluctuating electric fields at the NV center’s location. (b) Sketch of the experimental setup. Milled type Ib nano-size diamond is deposited on a solid immersion lens (SIL) and placed in a continuos flow He cryostat. Single-photon fluorescence is excited with a 532 nm laser and collected through an objective lens with numerical aperture $NA = 0.9$ . Using a spectral filter (BP) photons from the zero-phonon transition are filtered and sent through a folded Mach-Zehnder interferometer.Reuse & Permissions
Figure 2
Spectra of the ZPL from a typical nano-size diamond at a temperature of 5 K with a removable bandpass filter centered at the ZPL (637 nm). The green curve (upshifted by 0.3 for clarity) is the NV center’s fluorescence measured without the interferometer. The lower red curve is recorded after the interferometer. The inset shows the full NV spectrum with the yellow shaded area indicating the transmission of the bandpass filter.Reuse & Permissions
Figure 3
(a) Measured second-order autocorrelation function $g^{(2)} (τ)$ (red line) and cross correlation $g_{L R}^{(2)} (τ)$ (blue dots) of NV center 1 at an excitation laser power of $14.1 μ W$ . The bin size is increased for longer delays $τ$ , to decrease the error. The error of $g^{(2)} (τ)$ is in the order of the linewidth. The dip at zero time delay shows the single-photon character of the emission. (b) The probability $p (τ)$ that the ZPL remains constant on the order of 100 GHz within the time interval $τ$ calculated from the data shown in (a) according to Eq. (6). The bin size is increased for longer delays $τ$ , to decrease the error. The black line is an exponential fit to the data showing a spectral diffusion time $τ_{D}$ of $(4.6 \pm 0.6) μ s$ , while the dashed black line indicates the spectral diffusion time $τ_{D}$ ( $1 / e$ time).Reuse & Permissions
Figure 4
(a) Dependency of the spectral diffusion rate on the excitation power, measured on NV center 1. The straight line is a linear fit to the data with the jump rate at zero excitation power being a free fit parameter. The bend curve is a quadratic fit to the data. (b) The number of collected photons from the ZPL transition per spectral jump as a function of the excitation photon energy, as measured on NV center 2. The square data points were measured at equal photon count rates and varying excitation powers (left axis). Point size corresponds to the error bar. The dashed curve is a guide to the eyes. The circles show the spectral jump rate normalized to the excitation power, calculated from the same data set (right axis). It is clearly visible that the spectral diffusion rate increases dramatically above the threshold of about 2.3 eV.Reuse & Permissions

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