Abstract
Characterising the input-output photon-number distribution of an unknown optical quantum channel is an important task for many applications in quantum information processing. Ideally, this would require deterministic photon-number sources and photon-number-resolving detectors, but these technologies are still work-in-progress. In this work, we propose a general method to rigorously bound the input-output photon number distribution of an unknown optical channel using standard optical devices such as coherent light sources and non-photon-number-resolving detectors/homodyne detectors. To demonstrate the broad utility of our method, we consider the security analysis of practical quantum key distribution systems based on calibrated single-photon detectors and an experimental proposal to implement time-correlated single photon counting technology using homodyne detectors instead of single-photon detectors.
Highlights
Quantum photonics is the art of using low-light optical signals to exchange and process information in the quantum regime [1,2]
To demonstrate the broad utility of our method, we consider the security analysis of practical quantum key distribution systems based on calibrated single-photon detectors and an experimental proposal to implement time-correlated single-photon counting technology using homodyne detectors instead of single-photon detectors
IV we show how our method can be used to analyze the security of practical quantum key distribution (QKD) with calibrated detectors and Time correlated single-photon counting (TCSPC) using homodyne detectors
Summary
Quantum photonics is the art of using low-light optical signals to exchange and process information in the quantum regime [1,2]. In the most general setting, one considers the preparation, transmission, and detection of optical signals. The photonic channel of interest accepts an N -mode input state and returns an M -mode output state, which is measured by a series of photon-counting devices. MM ) photons across the M output modes given n = NN ) photons are injected into the channel (see Fig. 1). The knowledge of the channel is not needed to estimate q(m|n), i.e., we can treat the channel as a black box with N inputs and M outputs and sample .
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