Linearly multiplexed Photon Number Resolving single-photon detectors array
Leonardo Limongi, Francesco Martini, Thu Ha Dao, Alessandro Gaggero, Hamza Hasnaoui, Igor Lopez-Gonzalez, F. Chiarello, F. De Matteis, Alberto Quaranta, Andrea Salamon, F. Mattioli, Martino Bernard, Mirko Lobino
Photon Number Resolving Detectors (PNRDs) are devices capable of measuring the number of photons present in an incident optical beam, enabling light sources to be measured and characterized at the quantum level. In this paper, we explore the performance and design considerations of a linearly multiplexed photon number-resolving single-photon detector array, integrated on a single mode waveguide. Our investigation focus on defining and analyzing the fidelity of such an array under various conditions and proposing practical designs for its implementation. Through theoretical analysis and numerical simulations, we show how propagation losses and dark counts may have a strong impact on the performance of the system and highlight the importance of mitigating these effects in practical implementations.
Photon Number Resolving Detectors (PNRDs) are devices capable of measuring the number of photons present in an incident optical beam, enabling light sources to be measured and characterized at the quantum level. In this paper, we explore the performance and design considerations of a linearly multiplexed photon number-resolving single-photon detector array, integrated on a single mode waveguide. Our investigation focus on defining and analyzing the fidelity of such an array under various conditions and proposing practical designs for its implementation. Through theoretical analysis and numerical simulations, we show how propagation losses and dark counts may have a strong impact on the performance of the system and highlight the importance of mitigating these effects in practical implementations.
We present a photon-number resolving detector that merges variable- and fixed-efficiency single-photon detectors in one linear array. After a first, optimized section for high absorption, extra detectors with the minimum efficiency allowed by fabrication are added. Analytical and numerical tools show how the fidelity of variable- , uniform- and hybrid-efficiency arrays changes, while keeping the design manufacturable on lithium-niobate photonic circuits equipped with niobium-nitride nanowires. This scheme offers a realistic route to scalable, chip-level photon counting for quantum communication, computing and sensing
Photon-number-resolving detectors (PNRDs) play pivotal roles in many quantum-photonic applications; and intrinsic and multiplexed PNRDs have been reported previously. However, for intrinsic PNRDs, the maximum resolvable photon number is limited to a few photons; for the multiplexed PNRDs, the fidelity generally decreases when the to-be-resolved photon number becomes large. Here, to resolve more photons with high fidelity, we report on combined PNRDs, based on a spatial multiplexing configuration of multiple elements, each capable of resolving a few photons. After setting up a model and calculating the fidelity, we propose a possible physical system to realize the combined PNRDs. The proposed detectors are based on the superconducting nanowire multiphoton detectors integrated with current reservoirs that we recently reported, but are designed and configured into PNRDs. Specifically, information about the detected photon numbers is stored in the format of the supercurrent in the current reservoir and then readout by an integrated yTron. We present in detail the operating principle and show a design that can resolve up to 11 photons with high fidelity.
We investigate the feasibility and performance of photon-number-resolved photodetection employing single-photon avalanche photodiodes (SPADs) with low dark counts. While the main idea, to split n photons into m detection modes with a vanishing probability of more than one photon per mode, is not new, we investigate here a important variant of this situation where SPADs are side-coupled to the same waveguide rather than terminally coupled to a propagation tree. This prevents the nonideal SPAD quantum efficiency from contributing to photon loss. We propose a concrete SPAD segmented waveguide detector based on a vertical directional coupler design, and characterize its performance by evaluating the purities of Positive-Operator-Valued Measures (POVMs) in terms of number of SPADs, photon loss, dark counts, and electrical cross-talk.
Single-photon detectors are widely used in modern quantum optics experiments and applications. Like all detectors, it is important for these devices to be accurately calibrated. A single-photon detector is calibrated by determining its detection efficiency; the common method to measure this quantity requires comparison to another detector. Here, we suggest a method to measure the detection efficiency of a single-photon detector without requiring an external reference detector. Our method is valid for individual single-photon detectors as well as multiplexed detectors, which are known to be photon number resolving. The method exploits the even-number photon-statistics of a nonlinear source, as well as the nonlinear loss of a single-photon detector that occurs when multiple photons are incident simultaneously. We have analytically modeled multiplexed detectors and used the results to experimentally demonstrate the calibration of a single-photon detector without the need for an external reference detector.
Standard linear optical detectors have a maximum sensitivity in the few hundreds of photons range, limited by amplifier noise. On the other hand, single photon detectors, which are the most sensitive detectors, are strongly nonlinear: One or more photons result in the same output signal. Photon number resolving (PNR) detectors, which have the ability to discriminate the number of photons in a weak optical pulse, are of great importance in the field of quantum information processing and quantum cryptography. Moreover, a PNR detector with large dynamic range can cover the gap between these two detection modes. Such detectors are greatly desirable not only in quantum information science and technology, but also in any application dealing with low light levels. In this work, we propose a novel approach to photon number resolving detectors based on spatial multiplexing of nanowire superconducting single-photon detectors. In the proposed approach, N superconducting nanowires, each connected in parallel to an integrated resistor, are connected in series. Photon absorption in a nanowire switches its bias current to the parallel resistor, forming a voltage pulse across it. The sum of these voltages, proportional to the number of absorbed photons, is measured at the output. The use of a cryogenic preamplifier with high input impedance for the read-out increases the linearity, the signal to noise ratio, and the speed. With this combination, we expect to be able to count up to few tens of photons with high fidelity, excellent timing resolution, and very high sensitivity in the telecommunication wavelength range.
A novel photon-number-resolving detector (PNRD) structure, based on an array of nanowire superconducting single photon detectors (SSPDs) connected in series, have recently been proposed. With this configuration, it is possible to scale to large photon numbers. In this framework, PNRDs capable of resolving up to four, eight and twelve photons at telecommunication wavelengths have been fabricated and tested. The photon-induced voltage signals from all the series elements are summed up into a single readout pulse with a height proportional to the detected photon number. Analysis of the linearity shows the potential of scaling to an even larger dynamic range.