Exponential enhancement of quantum metrology using continuous variables

Understand

Coherence time is an important resource to generate enhancement in quantum metrology.

• In this work, based on continuous-variable models, we propose a new design of the signal-probe Hamiltonian which generates an exponential enhancement of measurement sensitivity.
• The key idea is to include into the system an ancilla that does not couple directly to the signal.
• An immediate benefit of such design is one can expand quantum Fisher information(QFI) into a power series in time, making it possible to achieve a higher-order time scaling in QFI.