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DTSTART:20230619T080000Z
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LOCATION:Auditorium and Online (Teams)
SUMMARY:ICFO | CRAIG CHISHOLM
CLASS:PUBLIC
DESCRIPTION:The exquisite control available in atomic ultracold quantum gas
 es experiments makes them an ideal candidate for quantum simulation of div
 erse topics ranging from high energy physics and analogue quantum gravity 
 to strongly correlated condensed matter systems and exotic states of matte
 r. This thesis describes the use of Raman coupling to engineer novel chira
 l interactions and a double well dispersion relation in potassium Bose-Ein
 stein condensates and exploits them to realise a topological gauge theory 
 and an exotic state of matter known as a supersolid\, respectively.\nA com
 mon feature of many topics of interest for quantum simulation is the abili
 ty to describe them from the perspective of a gauge theory. Raman coupling
  has been used to produce artificial gauge fields for more than a decade b
 ut usually the gauge fields lack the symmetry constraints necessary to con
 stitute a gauge theory. A well known gauge theory which is used to describ
 e fractional quantum Hall states is the Chern-Simons theory. The Chern-Sim
 ons theory is a topological gauge theory so does not have gauge field dyna
 mics in the absence of matter. We have used optical dressing to create chi
 ral interactions in a Bose-Einstein condensate of potassium atoms and enco
 de the dynamics of a one-dimensional reduction of the Chern-Simons theory 
 known as the chiral BF theory into the dynamics of the matter. We have obs
 erved chiral solitons and a density-dependent electric field. Our experime
 ntal results represent the first successful quantum simulation of a topolo
 gical gauge theory in the continuum.\nSupersolids were predicted theoretic
 ally more than fifty years ago and have been realised in Bose-Einstein con
 densates in recent years. In a second series of experiments\, we have take
 n advantage of the unique interaction properties of potassium to engineer 
 a supersolid in a Raman coupled Bose-Einstein condensate with greater stab
 ility and contrast than what can be achieved with other alkali atoms. Usin
 g matterwave optics techniques\, we have been able to image the characteri
 stic density modulations of a supersolid in a Raman coupled Bose-Einstein 
 condensate for the first time. We explore a previously inaccessible parame
 ter regime and demonstrate that the fringe spacing depends on the optical 
 intensity\, in contrast to a shallow optical lattice where the fringe spac
 ing is given by the lattice wavevector.\nOur method of engineering chiral 
 interactions broadens the field of quantum simulation of gauge theories to
  include topological gauge theories in the continuum and is a step towards
  simulating the Chern-Simons theory in two dimensions. Our application of 
 matterwave optics to the supersolid phase in a Raman coupled Bose-Einstein
  condensate introduces a new tool for probing low energy Goldstone modes a
 nd phase coherence properties.\nThesis Director: Prof Dr. Leticia Tarruell
DTSTAMP:20260405T122943Z
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