Building new tools capable of studying phenomena beyond the reach of current technologies opens exciting opportunities. Quantum sensors harness the small and fragile nature of the qubits to achieve extremely precise measurements, enabling breakthroughs in fundamental physics and real-world applications by pushing resolution and sensitivity to new limits.
In this talk, I’ll discuss two approaches to quantum-enhanced sensing. The first is developing a novel quantum sensor that can be placed closer to the target of interest. We introduce a surface molecular qubit formed by pentacene molecules scaffolded on a two-dimensional (2D) material, hexagonal boron nitride (hBN). This qubit exhibits stable fluorescence and optically detected magnetic resonance (ODMR) from cryogenic to ambient conditions. With fully deuterated pentacene, the Hahn-echo coherence time reaches 22 µs and extends to 214 µs under dynamical decoupling, outperforming state-of-the-art shallow NV centers in diamond despite being positioned directly on the surface.
The second approach leverages entanglement. I will introduce a variational method for generating metrological states in small dipolar-interacting spin ensembles with limited qubit control. Simulations show that, for both regular and disordered spatial configurations, the generated states enable sensing beyond the standard quantum limit (SQL) and, for small spin numbers, approach the Heisenberg limit (HL). The resulting states resemble Greenberger–Horne–Zeilinger (GHZ) states or spin-squeezed states (SSS). This advantage persists in the presence of finite spin initialization fidelity and a non-Markovian noise environment.