NbxTi1-xN low timing jitter single-photon detectors with unity internal detection efficiency at 1550 nm

• The requirements in quantum optics experiments for high single photon detectionefficiency, low timing jitter, low dark count rate and short dead time have been fulfilled withthe development of superconducting nanowire single photon detectors. Although they offer adetection efficiency above 90%, achieving a high time resolution in devices made ofamorphous materials is a challenge, particularly at temperatures above 0.8 K. Devices madefrom niobium nitride and niobium titanium nitride allow to reach the best timing jitter, but inturn have stronger requirements in terms of film quality to achieve a high efficiency. Here wetake advantage of the flexibility of reactive co-sputter deposition to tailor the composition ofNbxTi1-xN superconducting films, and show that a Nb fraction of x = 0.62 allows for thefabrication of detectors from films as thick as 9 nm and covering an active area of 20 μm,with a wide detection saturation plateau at telecom wavelengths and in particular at 1550 nm.This is a signature of an internal detection efficiency saturation, achieved while maintainingthe high time resolution associated with NbTiN and operation at 2.5K. With our optimizedrecipe, we reliably fabricated detectors with high critical current densities reaching asaturation plateau at 1550 nm with 80% system detection efficiency, and with a FWHMtiming jitter as low as 19.47 ps.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

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