Quantum Resonance viewed as Weak Measurement

Quantum resonance, i.e., amplification in transition probability available under certain conditions, offers a powerful means for determining fundamental quantities in physics, including the time duration of the second adopted in the SI units and neutron's electric dipole moment which is directly linked to CP violation. We revisit two of the typical examples, the Rabi resonance and the Ramsey resonance, and show that both of these represent the weak value amplification when involving significant enhancement of transition probabilities and that near the resonance points they share exactly the same behavior of transition probabilities except for the measurement strength whose difference leads to the known advantage of the Ramsey resonance in the sensitivity. Conversely, as a by-product of the relationship, we may measure the weak value through quantum resonance. In fact, we argue that previous measurements of neutron electric dipole moment based on the Ramsey resonance have potentially determined the weak value of neutron's spin with much higher precision than the conventional weak value measurement.