These phenomena correspond to poles of the S-matrix, and appear as peaks in the scattering cross-section. For 10 points each:
[10e] Name these metastable, short-lived quantum states that form when one particle scatters off another. Classically, this phenomenon occurs when an oscillating system grows in amplitude when driven at its natural frequency.
ANSWER: resonances
[10m] Resonances have complex values for this quantity, where the imaginary part measures the state's lifetime. These quantities are the eigenvalues of the operator H that appears in Schrödinger's equation.
ANSWER: energy [or total energy; accept energy levels; reject "kinetic energy" or "potential energy"]
[10h] This form of quantum resonance occurs when the energy of a scattering atom is close to the binding energy of a pair of atoms, allowing the free atom to be slowed to a halt. It can be exploited to create Bose-Einstein condensates.
ANSWER: Feshbach resonance
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