Siegert state approach to quantum defect theory

Quantum defect theory for cold chemistry with product-quantum-state resolution

We present a formalism for cold and ultracold atom-diatom chemical reactions that combines a quantum closecoupling method at short range with quantum defect theory at long range. The method yields full state-to-state rovibrationally resolved cross sections as in standard close-coupling (CC) calculations but at a considerably less computational expense. This hybrid approach exploits the simplici...

Covariance Approach to Quantum Theory

Multichannel quantum defect theory: a quantum Poincaré map

The multichannel quantum defect theory (MQDT) can be reinterpreted as a quantum Poincaré map in representation of angular momentum. This has two important implications: we have a paradigm of a true quantum Poincaré map without semiclassical input and we get an entirely new insight into the significance of MQDT. PACS: 05.45.Mt; 33.80.Rv; 03.65.Sq In recent years there has been a rapidly growing ...

Coherent State Approach to Quantum Clocks

The “problem of time” has been a pressing issue in quantum gravity for some time. To help understand this problem, Rovelli proposed a model of a two harmonic oscillators system where one of the oscillators can be thought of as a “clock” for the other oscillator thus giving a natural time reference frame for the system. Recently, the author has constructed an explicit form for the coherent state...

An Operational Approach to Quantum State Reduction

An operational approach to quantum state reduction, the state change of the measured system caused by a measurement of an observable conditional upon the outcome of measurement, is founded without assuming the projection postulate in any stages of the measuring process. Whereas the conventional formula assumes that the probe measurement satisfies the projection postulate, a new formula for dete...