Środowiskowe Seminarium z Informacji i Technologii Kwantowych

Multiparameter quantum metrology develops strategies to simultaneously estimate several parameters with quantum-enhanced precision and has potential applications in imaging and field sensing. The multiparameter sensitivity is quantified by the covariance matrix of all parameters. We present sensitivity limits for a multimode interferometer as matrix bounds for the covariance matrix. Quantum strategies to improve the precision may consist in entanglement among the parameter-encoding modes or among the particles that enter the interferometer (if their number is fixed). We observe a stepwise enhancement of the achievable precision limit as more modes and particles are entangled. We further discuss the optimal states for the various quantum and classical strategies.