QIPIRC

  Quantum entangled, or "Schrödinger cat", states can be very delicate and easily perturbed by their external environment. This sensitivity can be harnessed in measurement technology to create a quantum sensor with a capability of outperforming conventional devices at a fundamental level. In a paper recently published in Science, Jonathan Jones and his colleagues compared the magnetic field sensitivity of a classical (unentangled) system with that of a 10-qubit entangled state, realised by nuclear spins in a highly symmetric molecule (comprising nine ¹H nuclei around a central ³¹P). They observed a 9.4-fold quantum enhancement in the sensitivity to an applied field for the entangled system and showed that this spin-based approach can scale favorably compared to approaches where qubit loss is prevalent. This result demonstrates a method for magnetic field sensing technology, based on quantum entanglement.