Conference/School

There has been a surge of interest in indefinite causal structure the idea that cause and effect can no longer be sharply distinguished.  Motivated both by experimentation with quantum switches and quantum gravity there can be situations in which there is no matter-of-the-fact as to what the causal structure of spacetime is.  This meeting will bring together workers in Quantum Foundations and Quantum Gravity in both theoretical experimental physics to discuss the state of the art of current research and set new directions for this emerging subdiscipline.

Our conference covers three related subjects: quantum fault-tolerance magic states and resource theories and quantum computational phases of matter. The linking elements between them are (a) on the phenomenological side the persistence of computational power under perturbations and (b) on the theory side symmetry. The latter is necessary for the working of all three. The subjects are close but not identical and we expect cross-fertilization between them.Fault tolerance is an essential component of universal scalable quantum computing.However known practical methods of achieving fault tolerance are extremely resource intensive. Distillation of magic states is in the current paradigm of fault-tolerance the costliest operational component by a large margin. It is therefore pertinent to improve the efficiency of such procedures study theoretical limits of efficiency and more generally to establish a resource theory of quantum state magic. During the workshop we will focus on a fundamental connection between fault-tolerant protocols and symmetries.``Computational phases of matters are a surprising link between quantum computation and condensed matter physics. Namely in the presence of suitable symmetries the ground states of spin Hamiltonians have computational power within the scheme of measurement-based quantum computation and this power is uniform across physical phases. Several computationally universal phases have to date been discovered. This subject is distinct from the above but linked to them by the feature of persistence of computational power under deformations and deviations.

Understanding the small-scale structure of spacetime is one of the biggest challenges faced by  modern theoretical physics. There are many different attempts to solve this problem and they reflect the diversity of approaches to quantum gravity. This workshop will bring together researchers from a wide range of quantum gravity approaches and give them an opportunity to exchange ideas and gain  new insights.

One of the biggest mysteries in cosmology and fundamental physics is the nature of dark energy that is responsible for the current acceleration of cosmic expansion. While a cosmological constant provides the simplest model of dark energy recent observational tensions amongst supernovae Ia gravitational lensing time delays and cosmic microwave background suggest the need for a more complex dynamical dark energy. One of the oldest proposals for a dynamical dark energy is Everpresent Lambda proposed by Sorkin which is inspired by the causal set model of quantum gravity. It was recently shown that this model can potentially resolve the  tensions in cosmological observations. The meeting aims to bring together a small number of experts in quantum gravity causal sets and cosmology to carefully examine the models theoretical predictions and its observational tests and pave the way for what might be an(other) exciting insight from cosmology into the fundamental nature of spacetime.

This cross-disciplinary workshop gathers theorists who have been working on novel approaches to understanding the structure of the Standard Model and its link to cosmology and gravity. It follows the previous Simplicity I and II workshops at Princeton University (2014) and Fermilab (2016) and will be a small informal meeting with plenty of room for discussions.