Research

Recent research highlights

Emergent non-Markovianity in time-delayed waveguide QED

We looked at what happens when emitters interact via photons that take time to propagate. By thinking about an array of increasing emitter number but constant length, we extracted the relevant scaling for when propagation times matter in the single-excitation regime. The impact of memory is intrinsically state selective. In the worst case, one has to consider the ratio between the end-to-end propagation time and the collective superradiant lifetime.

You can take a look at our paper on the arXiv!

Exact many-body quantum dynamics in one-dimensional baths via "superspins"

We considered partial symmetries in emitter arrays coupled to one-dimensional baths, such as single-mode waveguides and ring cavities. We found that these partial symmetries can be utilized to reduce the complexity from an exponential scaling with particle number to polynomial. We showed how this allows us to calculate exact many-body dynamics for large particle number, studying superradiance and the emergence of metrologically useful dark states.

For more details, see the paper here!

Optomechnical self-organization in a mesoscopic atom array

Collaborators at Berkeley investigated self-organization in a driven tweezer array inside a cavity. At some critical drive strength, the light scattered by the atoms into the cavity provides a deeper potential than the tweezers, and they all shift their positions in a synchronized manner. While well established for bulk gases, the tweezer array allows for exploration with a small fixed number of atoms, and the observation of mesoscopic signatures of phase transitions.

You can read about it in Nature Physics!

Generating photonic entangled states using decoherence free subspaces

We devised a protocol to generate strings of entangled photons using dark collective states generated by three quantum emitters coupled to a waveguide truncated at one end by a mirror. By performing gates on the collective states, emitted photons are entangled and create states such as GHZ states and cluster states, with applications in metrology and quantum computing. In a followup, we showed to stabilize and prepare single- and multi-excitation dark states in the same setup.

See the paper in PRL and the follow up on arXiv!

Modification of branching ratios by collective many-body decay

We explored the physics of collective decay from an excited state with multiple decay paths. We showed that decay from a fully inverted collective state depends not only on the branching ratios between decay paths but the number of emitters, tending to be completely dominated by the most likely path as the emitter number becomes very large. We highlighted the potential use of collective decay for photoassociation of ultracold molecules.

Read about it in Physical Review Research!

Alkaline-earth atoms as a platform to study many-body quantum optics

We considered arrays of alkaline-earth atoms for many-body quantum optics, as the presence of long-wavelength transitions allows these atoms to be spaced relatively very close. We showed that Dicke superradiance manifests in experimentally feasible arrays, despite the complicated level structure, and in fact allows for the modification of decay ratios. Our work highlights the potential resource of alkaline-earth atom arrays as quantum optical devices.