Quantum Entanglement Enables Single-Shot Trajectory Sensing for Weakly Interacting Particles

Sensors for mapping the trajectory of an incoming particle find important utility in experimental high energy physics and searches for dark matter. For a quantum sensing protocol that uses projective measurements on a multiqubit sensor array to infer the trajectory of an incident particle, we establish that entanglement can dramatically reduce the particle-qubit interaction strength θ required for perfect trajectory discrimination. Within an interval of θ above this reduced threshold, any unentangled sensor requires Θ[log(1/ε)] repetitions of the protocol to estimate a previously unknown particle trajectory with ε error probability, whereas an entangled sensor can succeed with zero error in a single shot. Furthermore, entanglement can enhance trajectory sensing in realistic scenarios where θ varies continuously over the sensor qubits, exemplified by a Gaussian-profile laser pulse propagating through an array of atoms.