Research
The central goal of the UVAMO lab is to develop the technology required for a long-distance quantum network. A quantum internet — one capable of sharing entanglement between arbitrary nodes — would enable quantum key distribution, distributed quantum computing, and enhanced sensing far beyond what classical networks can offer. We contribute to this vision by building and characterizing the key physical components of a quantum node, using rubidium atomic ensembles as our primary platform.
The Quantum Node
A functional quantum repeater node requires three interconnected capabilities: a quantum memory to store and synchronize entanglement, a wavelength converter to interface with existing telecom fiber infrastructure, and a high-quality nonclassical light source to generate the entangled states in the first place. We are developing all three in parallel, with the long-term goal of benchmarking a complete integrated node.
Field-Deployable Quantum Memory
We are benchmarking an electromagnetically induced transparency (EIT) memory in warm rubidium vapour. EIT allows a photonic qubit to be coherently mapped onto a long-lived collective spin excitation in the atomic ensemble, then retrieved on demand. Room-temperature operation makes this approach far more practical than cryogenic alternatives.
Key figures of merit are storage efficiency, fidelity, and coherence time. We encode qubits in polarization and use a dual-rail scheme to interface with the memory. A central focus is understanding how realistic memory imperfections — finite efficiency, finite coherence — affect entanglement distribution rates over a full repeater network.
Atomic–Telecom Wavelength Conversion
Rubidium operates near 795 nm, where fiber loss is approximately 10 dB/km — unusable for long-distance transmission. Telecom C-band (1550 nm) reduces this to 0.2 dB/km, a factor of 50 improvement. We use four-wave mixing (4WM) in a diamond-level configuration in Rb to quantum-coherently convert photons between the atomic and telecom wavelengths, preserving the quantum state throughout.
Conversion efficiency scales with the optical depth of the atomic ensemble. To reach high efficiency we are constructing an ultra-high optical depth magneto-optical trap (MOT), which will also serve as the platform for next-generation memory experiments.
Cavity-Enhanced Squeezed Light Source
We are developing a source of nonclassical light based on four-wave mixing in rubidium vapour in a Λ configuration. This process generates correlated photon pairs whose noise properties fall below the quantum shot-noise limit — squeezed states — which are a key resource for both continuous-variable quantum information and heralded single-photon generation.
By placing the 4WM medium inside an optical cavity we aim to enhance the nonlinear interaction and produce single-spatial-mode squeezed states suitable for direct injection into our memory and converter experiments, completing the node.
The Grand Vision
The three experiments are designed to work together: E3 provides the entangled photon source, E2 converts one photon of each pair to telecom wavelength for transmission through fiber, and E1 stores the other locally while the remote link is established. Together they constitute a complete, benchmarked quantum repeater node — our long-term experimental target.