Efficient and precise photon-number-resolving detectors are essential for optical quantum information science. Despite this, very few detectors have been able to distinguish photon numbers with both high fidelity and a large dynamic range, all while maintaining high speed and high timing precision. Superconducting nanostrip-based detectors excel at counting single photons efficiently and rapidly, but face challenges in balancing dynamic range and fidelity. Here, we have pioneered the demonstration of 10 true photon-number resolution using a superconducting microstrip detector, with readout fidelity reaching an impressive 98% and 90% for 4-photon and 6-photon events, respectively. Furthermore, our proposed dual-channel timing setup drastically reduces the amount of data acquisition by 3 orders of magnitude, allowing for real-time photon-number readout. We then demonstrate the utility of our scheme by implementing a quantum random-number generator based on sampling the parity of a coherent state, which guarantees inherent unbiasedness, robustness against experimental imperfections and environmental noise, as well as invulnerability to eavesdropping. Our solution boasts high fidelity, a large dynamic range, and real-time characterization for photon-number resolution and simplicity with respect to device structure, fabrication, and readout, which may provide a promising avenue towards optical quantum information science.
A photon number resolving detector (PNRD) is a device providing a different output depending on the number of incident photons in the single or few photons regime. This tool is crucial in several applications such as quantum communication, boson sampling, photon sources characterization and so on. PNRD are not new players in ultraviolet or visible wavelengths, but superconducting nanostrips provide a performing counterpart also in the near-infrared, where the aforementioned applications would like to operate. In this work we present a comprehensive description of the operation of an eight-pixel PNRD at the telecom wavelength of 1550 nm.
In the quest to realize a scalable quantum network, semiconductor quantum dots (QDs) offer distinct advantages, including high single-photon efficiency and indistinguishability, high repetition rate (tens of gigahertz with Purcell enhancement), interconnectivity with spin qubits, and a scalable on-chip platform. However, in the past two decades, the visibility of quantum interference between independent QDs rarely went beyond the classical limit of 50%, and the distances were limited from a few meters to kilometers. Here, we report quantum interference between two single photons from independent QDs separated by a 302 km optical fiber. The single photons are generated from resonantly driven single QDs deterministically coupled to microcavities. Quantum frequency conversions are used to eliminate the QD inhomogeneity and shift the emission wavelength to the telecommunication band. The observed interference visibility is 0.67 ± 0.02 (0.93 ± 0.04) without (with) temporal filtering. Feasible improvements can further extend the distance to ∼600 km. Our work represents a key step to long-distance solid-state quantum networks.
We realize quantum computational advantage in a Gaussian Boson Sampling (GBS) experiment. We inject 25 two mode squeezed states into a 100-mode ultralow-loss interferometer with full connectivity and random matrix. We rule out thermal states, distinguishable photons, and uniform distribution hypotheses. This GBS machine can sample 14 orders of magnitude faster than classical supercomputer.
We report a polarization-dependent reflector beyond normal incidence with a subwavelength nanoparticle chain. Polarization-dependent reflection with high reflectivity or high transmissivity can be obtained with this structure. Light waves of transverse electric/magnetic mode will be reflected, while the transverse magnetic/electric mode will transmit through. The structure shows a certain degree of tolerance of incident angle, technical fabrication, and even particle shape. We hope the low-loss and compact structure can find applications in photonic circuits such as gallium nitride-based light sources.
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