Optical fiber based quantum light source

Alex O. C. Davis, Leah R. Murphy, Alex R. McMillan +3 more

Fiber optical parametric oscillators are being busily investigated as sources of classical light, but are comparatively neglected as potential quantum light sources. Squeezed light is a crucial resource for emerging quantum technologies for computing, communications, and measurement. The direct generation of squeezed light inside optical fiber is of particular interest due to minimal material loss, desirable mode properties and compatibility with long-distance optical networks. Here, we describe a novel all-fiber continuous-wave optical parametric oscillator developed with the aim of generating squeezed light. Our device is based on a 10 cm Fabry-Perot cavity formed by two high-reflectivity fiber Bragg gratings written directly into a single section of photonic crystal fiber. This enables low-loss optical feedback and strongly resonance-enhanced four-wave mixing, with a cavity finesse of up to 400. We observe resonance-enhanced four-wave mixing in these devices, demonstrating a step towards their application as quantum light sources.

Alexander V. Andrianov, N. A. Kalinin, A. A. Sorokin +2 more

Jonny Roberts, Robert James Young

Mayank Joshi, Tanumoy Pramanik, Mengting Jiang +9 more

Miniaturized quantum light sources that operate directly in optical fibers are an attractive platform for optical quantum technologies. However, most miniaturized spontaneous parametric down- conversion (SPDC) sources still rely on objective-lens-based free-space pumping and collection, which limits compactness, robustness, and direct compatibility with fiber-based systems. Here we demonstrate a lens-free in-line SPDC photon-pair source by integrating a van der Waals NbOI2 flake directly onto the end facet of an optical fiber. In this configuration, the generated photon- pairs are efficiently collected into optical fibers, eliminating the need for bulk free-space collection optics. Despite the limited numerical aperture of the single-mode fiber, efficient photon-pair collection with high purity, characterized by a coincidence-to-accidental ratio of up to ~4600, is achieved in an ultracompact configuration. These results establish van der Waals ferroelectric materials as a promising platform for fiber-integrated quantum light sources and provide a pathway toward compact, alignment-free quantum photonic devices.

Alexander Schlehahn, Sarah Fischbach, Ronny Schmidt +5 more

Abstract In this work, we present a stand-alone and fiber-coupled quantum-light source. The plug-and-play device is based on an optically driven quantum dot delivering single photons via an optical fiber. The quantum dot is deterministically integrated in a monolithic microlens which is precisely coupled to the core of an optical fiber via active optical alignment and epoxide adhesive bonding. The rigidly coupled fiber-emitter assembly is integrated in a compact Stirling cryocooler with a base temperature of 35 K. We benchmark our practical quantum device via photon auto-correlation measurements revealing g(2)(0) = 0.07 ± 0.05 under continuous-wave excitation and we demonstrate triggered non-classical light at a repetition rate of 80 MHz. The long-term stability of our quantum light source is evaluated by endurance tests showing that the fiber-coupled quantum dot emission is stable within 4% over several successive cool-down/warm-up cycles. Additionally, we demonstrate non-classical photon emission for a user-intervention-free 100-hour test run and stable single-photon count rates up to 11.7 kHz with a standard deviation of 4%.

Prem Kumar, Jun shuo Chen, Paul L. Voss +3 more