Find out about our latest quantum talks.
24 January 2020 - Professor Rene Gerritsma (Universiteit van Amsterdam) The Quantum Physics of Interacting Atoms and Ions.
In recent years, a novel field of physics and chemistry has developed in which trapped ions and ultracold atomic gases are made to interact with each other. These systems find applications in studying quantum chemistry and collisions, and a number of quantum applications are envisioned such as ultracold buffergas cooling of the trapped ion quantum computer and quantum simulation of fermion-phonon coupling. Remarkably, in spite of its importance, experiments with atom-ion mixtures remained firmly confined to the classical collision regime. This is because the electric traps used to hold the ions cause heating during atom-ion collisions. In our experiment, we overlap a cloud of ultracold 6Li atoms in a dipole trap with a 171Yb+ ion in a Paul trap. The large mass ratio of this combination allows us to suppress trap-induced heating. For the first time, we buffer gas-cooled a single Yb+ ion to temperatures close to the quantum (or s-wave) limit for 6Li-Yb+ collisions. We find significant deviations from classical predictions for the temperature dependence of the spin exchange rates in these collisions. Our results open up the possibility to study trapped atom-ion mixtures in the quantum regime for the first time. Finally, I will present our plans on a new experimental setup that we are currently building, in which we aim to manipulate the soundwave spectrum of large ion crystals using SLM-controlled optical tweezers. The resulting platform can be used for quantum simulation of quantum spin models.
16 January 2020 - Professor Igor Lesanovski (Eberhard Karls Universität Tübingen) Constrained Dynamics and Electron-phonon Coupling in Rydberg Quantum Simulators.
Rydberg quantum simulators, i.e. highly excited atoms held in optical tweezer arrays, belong to the currently most advanced platforms for the implementation and study of strongly interacting spin systems. An interesting dynamical regime is reached when one atom that is brought to a Rydberg state facilitates the excitation of another nearby one. The resulting dynamics can be similar to that of epidemic spreading and also may form an ingredient for observing non-equilibrium phase transitions. In my talk I will discuss recent results concerning the analysis of constrained spin dynamics on Rydberg quantum simulators. In this context I will also focus on the inevitable coupling between Rydberg excitations and vibrational degrees of freedom which permit the engineering of exotic types of interaction.
16 January 2020 - Dr Auro Perego (University of Aston) Gain-through-loss: Theory and Applications in Nonlinear Photonics.
Optical losses are in general considered to be a detrimental effect which reduces the efficiency of photonic devices and that hence must be avoided. Although this may be in many cases true, there are very relevant and counterintuitive situations where modes suffering optical losses are amplified in virtue of losses presence itself.
I will review our research on a still not well known and unexploited class of modulation instabilities caused by spectrally dependent losses in nonlinear optical systems with cubic and quadratic nonlinearity. I will show how energy dissipation can be engineered to design a new class of amplifiers and parametric oscillators operating without satisfying standard phase-matching conditions, and tuneable repetition rate optical frequency comb sources in normal dispersion Kerr resonators. The universality of the dynamical process underpinning this loss-enabled behaviour makes its observation possible even in other nonlinear systems beyond photonics.