Light Trap: Holding the Elusive ⚡ экспресс
Scalable quantum networks and photonic processors require integrated photonic memories with high storage efficiency. Existing integrated systems are limited to efficiencies under 27.8%. We present high-efficiency quantum memories based on crystals doped with rare-earth ions Eu3+:Y2SiO5, embedded in impedance-matched microresonators. Two architectures were realized: 200-µm-thick membranes with fiber microresonators and waveguide resonators fabricated via femtosecond laser. We achieved record storage efficiencies for integrated systems: 80.3(7)% for weak coherent pulses and 69.8(1.6)% for single photons, along with simultaneous storage of 20 temporal modes at an average efficiency of 51.3(2)%. The thin-film architecture allows spectral tuning through controlled strain, enabling flexible interfacing in quantum networks. The combination of high efficiency, multimodality, and tunability creates a versatile hardware platform for scalable quantum repeaters and chip-scale photonic processors.
For quantum internet, light needs to be delayed—like mail at a sorting center. At the core is a thin crystal plate with europium ions (the element that gives red glow to smartphone screens). Placed between two mirrors, the crystal forms a trap. Light, ricocheting inside, is absorbed by an ion and emitted back a moment later—just like a mailbox that accepts and returns letters.
Thanks to spectroscopy, ideal materials were selected. Efficiency: 80% for laser pulses and nearly 70% for single photons from optical fiber. According to the Standard Model, light always travels at the speed of light, but here it freezes.
A thin membrane allows tuning the color of captured light with a gentle press—like a mailbox with an adjustable slot. This builds on the single-photon experiments of Serge Haroche and Jeff Kimble, now embodied in chips for quantum repeaters and optical processors.
🎯 A crystal with europium ions can store a light pulse for longer than a millisecond—by quantum standards, that's an eternity, during which light would circle the Earth more than seven times.