Abstract
The paper presents a system for measuring photon statistics and photon timing in the few-photon regime down to the single-photon level. The measurement system is based on superconducting nanowire single photon detectors and a time-to-digital converter implemented into a programmable device. The combination of these devices gives high performance to the system in terms of resolution and adaptability to the actual experimental conditions. As a case of application, we present the measurement of photon statistics for coherent light states. In this measurement, we make use of 8th order single photon correlations to reconstruct with high fidelity the statistics of a coherent state with average photon number up to 4. The processing is performed by means of a tapped-delay-line time-to-digital converter architecture that also hosts an asynchronous-correlated-digital-counter implemented in a field programmable gate array device and specifically designed for performance optimization in multi-channel usage.
Highlights
Sensitive light sensing can be performed by observing the transition of a section of a current-biased superconducting nanowire from the superconducting state to the normal resistive state, as a result of photon absorption
The measurement system is based on superconducting nanowire single photon detectors and a time-to-digital converter implemented into a programmable device
The results demonstrate that using superconducting nanowire detectors coupled to a multichannel TDL-TDC/ACDC we can perform up to 8-fold photon coincidence measurements and measure with the ACDC the photon statistics of coherent states of light arriving at the beam splitter
Summary
Sensitive light sensing can be performed by observing the transition of a section of a current-biased superconducting nanowire from the superconducting state to the normal resistive state, as a result of photon absorption Devices based on this principle are called Superconducting nanowire single photon detectors (SNSPDs) and find application in several areas of quantum information technology for their ability of detecting single photons with near unity probability in a large wavelength range from UV to infrared. In addition to high photon detection efficiency, SNSPDs provide several advantages in comparison to other single-photon sensitive devices: extremely low timing jitter, the absence of afterpulsing, and the low dark count rate Such performances make them the ideal detector for applications where efficient detection of weak signals with high time resolution is required.
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