Entropy Removal and Coherence with Lasers

The creation of low entropy states is crucial to modern atomic and molecular physics as particle cooling has opened the way for the creation of ultracold superfluid, quantum simulators, and increasing the precision of atomic clocks. However, it is often unclear how the particle ensemble’s entropy is redistributed to other subsystems during the cooling process. Furthermore, experimental control of quantum systems during its interaction with laser fields is often impaired by incoherent, spontaneous processes that may transfer particles to unwanted states. With these points in mind, my honors thesis focuses on protocols that create low entropy states as well as schemes that increase coherent control in quantum evolution. First, we present a method for creating high impulse laser slowing protocols that mitigate the effects of incoherent jumps by evolving the system with an adiabatic shortcut. Once the particles are slowed, they are often cooled using laser fields. This is the process under investigation next as we demonstrate that the laser fields themselves can absorb atomic entropy during their coherent dynamics. We then dedicate our study to the steady-state superradiance model in the weak pumping regime. Here, we investigate the properties of the subradiant state and the appearance of an “enhancement threshold” where the subradiant state may be extracted for high atom numbers in an experimental setting. These states are insensitive to spontaneous emission and can therefore protect the evolution of a system during a quantum metrological process on atomic platforms.