arXiv subjects

Maya Büki

Publications and source records attributed to Maya Büki.

3 recordsLinked to original sources

arXiv2026

Metropolitan entanglement distribution between an atom and a near-visible photon

Entanglement distribution is the overarching purpose of quantum networks. While communication over long distances can use deployed fiber infrastructure, it requires photons in the telecom band. However, advanced quantum network nodes do not operate at such wavelengths. Here we overcome this limitation with two tailor-made low-noise quantum-frequency converters to distribute entanglement between a single atom and a resonant photon over 14km line-of-sight via 24km of a deployed commercial fiber. The photon at wavelength 780nm is first entangled with the atom, then converted to the telecom S-band, and finally back-converted after propagation through the fiber. This link enables a photon transfer efficiency of 1.7% while affecting the atom-photon entanglement fidelity by less than 1%. This brings integration of atomic quantum nodes with existing long-distance fiber networks into reach, enabling novel applications in quantum information processing.

quant-ph↗

arXiv2026

Efficient entanglement of three remote single-atom quantum-network nodes

Entanglement distributed over a set of individually addressable qubit nodes is the enabling resource for a plethora of applications ranging from tests of quantum physics to secure and modular quantum information networks. Entanglement between two memory qubits has been realized on various platforms, but extension to more nodes remains rare and formidably challenging. The principal bottleneck is the efficiency of the light-matter interfaces connecting the qubit nodes to their communication channels. Here, we efficiently generate, distribute and store a three-qubit entangled state across three independent laboratories containing single atoms coupled to optical resonators. We sequentially entangle the atoms pairwise, two by heralded photonic entanglement swapping and two by heralded state transfer. We reach a three-qubit entanglement fidelity of 77(1)% and an entanglement lifetime above 200us. The observed qubit correlations violate Mermin's inequality while closing the detection loophole. Our three-qubit entanglement-generation efficiency is 0.16%. This unprecedented efficiency of our scheme establishes a clear route towards multi-node quantum networks.

quant-ph↗

arXiv2021

A frequency quintupled laser at 308 nm for spectroscopy of intercombination lines in zinc

Many experiments in atomic physics and quantum optics, among them optical atomic clocks, require laser sources in the ultra-violet wavelength range with very low intensity noise and phase noise. The development of such lasers is a challenge, especially when a robust and transportable system is required. Here, we report on the development of a novel continuous wave (cw) frequency-quintupled laser at 308 nm with an output power of 0.5 mW, based on a fiber laser operating in the telecom band. Three consecutive frequency conversion stages in nonlinear crystals are employed. The performance of the laser system is demonstrated by linear absorption spectroscopy of a narrow intercombination line in zinc.

physics.optics↗