Session B04: AMO I

On macroscopic quantum coherence: 'Brightened' emissions from collective atoms and molecules

Collective behaviors of quantum particles are one of the most intriguing phenomena in quantum optics. When quantum particles behave collectively as a whole due to the buildup of macroscopic quantum coherence, they emit a burst of light referred to as superradiance. In this talk, I will begin with Dicke superradiance and introduce new cascade superradiance model. Selected experimental studies exploring superradiance in rubidium, cesium and sodium atomic vapors will be discussed. Finally, I will explain a deferred buildup of macroscopic quantum coherence for molecular vibrational states.

    

Life at the edge: Fermionic superfluidity in ultracold atomic gases near a boundary

Theoretically, for ultracold atomic gases in the many-body regime it is common to approximate the microscopic van der Waals potential by a delta-function with an unspecified coupling constant. This unknown coupling constant can usually be related to a measurable physical parameter; in ultracold gases this is done by connecting it to the s-wave scattering length. However, an additional technicality occurs with a delta-function interaction in dimensions greater than one. In two- and three-dimensions, a short-ranged attractive interaction leads to unphysical divergences in various quantities, for example, the bound state energy or the superfluid pairing amplitude become divergent. It is well-known that in the bulk, far away from any boundaries, these divergences can be systematically healed via a renormalization of the coupling constant, but for trapped systems or near a boundary there is no clear-cut prescription to heal these divergences and simultaneously satisfy arbitrary boundary conditions. In this talk, I will discuss some prior work on solving this problem for the local superfluid pairing, as well as some preliminary results of our own. For a fermionic superfluid, we formalize how to regularize the local pairing amplitude and satisfy a given boundary condition. Applying this formulation to a fermionic superfluid with single hard-wall boundary, we find a large enhancement of the superfluid pairing near the boundary, but essentially no change in the superfluid transition temperature, which is something that has been predicted to occur in a superconducting system.   

How a Galvanic Cell Detects a Closed Circuit Without Using Electricity

Within a circuit, galvanic reactants do not have a means of detecting a switch closing.  During the switch closing, no photons, electricity, electrical pathways, ion pathways or other communication within or between components necessarily exist within the circuit. 

 

When 2 molecules chemically combine, communications are established between them.  We (outlandishly) propose that the communication established via the switch closing is via all the molecules within the entire electric circuit temporarily combining into a single molecule. 

 

A galvanic reaction will not occur until the reactants have a place to put electrostatic energy.  The 2V voltage gradient from a lead acid galvanic reaction cannot be stably contained within a single atom. 

 

The molecules within a circuit can combine into a single molecule, to accommodate electrostatic and/or magnetic energy. 

 

As the molecules within the circuit chemically combine to become a container of electrostatic energy, the anode and cathode reactants automatically become part of the single molecule.  Once part of a single molecule, galvanic reactants can have a galvanic reaction. 

 

Our experiment indicated that the volts across the electrolyte of a galvanic cell within a galvanic circuit are less than the volts across the length of the circuit.  Therefore, the connections between circuit components that temporarily exist during a galvanic reaction can differ from subsequent connections.