A Molecule‐Based Single‐Photon Source Applied in Quantum Radiometry

Abstract

Single‐photon sources (SPSs) based on quantum emitters hold promise in quantum radiometry as metrology standard for photon fluxes at the low light level. Ideally this requires control over the photon flux in a wide dynamic range, sub‐Poissonian photon statistics, and narrow‐band emission spectrum. In this work, a monochromatic SPS based on an organic dye molecule is presented, whose photon flux is traceably measured to be adjustable between 144 000 and 1320 000 photons per second at a wavelength of (785.6 ± 0.1) nm, corresponding to an optical radiant flux between 36.5 and 334 fW. The high purity of the single‐photon stream is verified, with a second‐order autocorrelation function at zero time delay below 0.1 throughout the whole range. Such molecule‐based SPS is hence used for the calibration of a single‐photon avalanche detector against a low‐noise analog photodiode traceable to the primary standard for optical radiant flux (i.e., the cryogenic radiometer). Due to the narrow bandwidth of the source, corrections to the detector efficiency arising from the spectral power distribution are negligible. With this major advantage, the developed device may finally realize a low‐photon‐flux standard source for quantum radiometry.

Laser-Induced Frequency Tuning of Fourier-Limited Single-Molecule Emitters

“…Notably, the emission purity for single-photon-based applications is not compromised by such background levels (see SI, Figure S3), since the pump power employed for single-photon source operation is much lower than that used to shift the ZPL frequency, yielding a negligible background level. 26 In particular, the statistical analysis of g (2) (t) measurements on 40 DBT:Ac nanocrystals performed in our previous work 27 yields a single-photon purity higher than 97% for 82% of the cases.…”

Second‐Order Autocorrelation Function of Spectrally Filtered Light From an Incoherently Pumped Two‐Level System

“…Corresponding second-order autocorrelation function is shown on the Figure 1d-f. The filter (22) cannot be transformed to Lorentz filter (20). Moreover, this filter better suppresses the light intensity for the frequencies far from 𝜔 F compared to the Lorentzian filter (∝ 𝜔 −4 compared to ∝ 𝜔 −2 for Lorentzian filter).…”

“…This is due to their applications in encoding/decoding information, [1][2][3][4] quantum computing, [5,6] quantum cryptography, [7,8] manipulating quantum mechanical objects, [2,9,10] and integral nanophotonics. [11,12] An SPS can be realized in quantum dots, [13][14][15][16][17][18] single molecules, [19,20] NV and SiV centers, [21][22][23][24][25][26] 2D materials. [27,28] From a practical point of view, it is of interest to control the rate and pattern of radiation from the SPS while simultaneously maintaining g (2) (0) close to zero.…”

Photonic Quantum Technologies

“…The single-photon stream is linked to a national radiometric standard via an analog Si detector calibrated through an unbroken traceability chain. [15] -Nanobeam PhC cavities on SiO 2 substrates in the visible wavelength for the coupling of nanoscale emitters to photonic integrated circuits are designed and fabricated. [16] -Recent work in the field of self-assembled InAs/GaAs coupled quantum dots (CQDs) is reviewed.…”