Unlocking quantum secrets with entangled neutrons

Einstein called it ‘spooky action at a distance.’ Schrödinger deemed it quantum mechanics’ most essential trait. For decades, quantum entanglement has captivated the brightest minds—and now, we can create entangled neutrons using a standard neutron scattering instrument.

Entangled neutrons were first measured using the neutron resonance spin-echo spectrometer RESEDA. © Reiner Müller, FRM II / TUM

Entangled neutrons were first measured using the neutron resonance spin-echo spectrometer RESEDA. © Reiner Müller, FRM II / TUM

While quantum entanglement—recognized with the 2022 Nobel Prize in Physics paved the way for ultra-secure communications and advanced computing, its significance extends far beyond quantum information technology, reaching deep into the foundations of condensed matter physics and beyond.

Quantum entanglement in condensed matter physics
Quantum spin liquids, for example, possess a quantum entangled ground state—the system’s lowest-energy configuration, which it adopts as it approaches absolute zero. However, demonstrating the existence of such a state remains an experimental challenge pursued by researchers worldwide.

Dr. Johanna Jochum, co-author of the publication, on the RESEDA instrument. © MCQST by Jan Greune

Dr. Johanna Jochum, co-author of the publication, on the RESEDA instrument. © MCQST by Jan Greune

Neutrons to explore entangled states

Neutron spectroscopy has been a vital tool in this pursuit, enabling researchers to probe a material’s excitation spectrum for signs of entanglement. Recently, a global team of researchers demonstrated progress by showing that a neutron resonance spin-echo spectrometer—such as RESEDA the MLZ—can produce a beam of entangled neutrons. An entangled beam of neutrons opens new possibilities for probing condensed matter systems, providing a powerful tool to explore quantum entanglement.