I am currently working at the University of Massachusetts with a postdoctoral fellowship from the Wenner-Gren foundations in Stockholm.

SCIENTIFIC INTERESTS

Statistical properties of Strongly correlated systems
I am currently working with Boris Svistunov and Nikolay Prokof’ev to develop new computational strategies for strongly correlated fermionic systems. In particular we are exploring using Diagrammatic Monte Carlo in combination with transformation techniques like fermionisation. Recently we have developed a mapping based on spin-charge transofmration in order to address statistical properties the t-J model (arXiv 2016).

Dynamics of strongly interacting systems
An open fundamental question in quantum mechanics is the nature of propagation in an environment that posses a memory of particle trajectories. A basic example of this is a hole moving in a degenerate spin environment. This canonical problem has important connections to fundamental properties of strongly correlated systems, such as density of states. Recently we published the first large scale simulations exploring this topic (PRL 2016).

Phase transitions in Multicomponent Superconductors
Multiband models support entropically stabilised states with additional superfluid channels. This is in stark contrast to the usual scenario where thermal fluctuations destroy superfluidity. This finding was awarded editors suggestion (PRL 2014) and was also featured in Nature Physics.

Frustrated Superconductors
Transitions between broken and unbroken time-reversal symmetry in frustrated superconducting systems is associated with massless Leggett modes. The state with broken time-reversal symmetry also features a mass matrix that mixes the phase and amplitude sectors so that perturbations to amplitude necessitates perturbation to the phase differences and vice versa. This gives rise to a new mechanism for long range intervortex interaction (PRB 2011).
Frustrated superconductors also support a new form of topological flux-carrying objects in the form of solitons (
PRL 2011). These solitons exhibit a chirality, something which was awarded editors suggestion (PRB 2013).

Type-1.5 Superconductivity
Non-monotonic intervortex forces resulting from the presence of additional length scales in multicomponent superconductors give rise to a new magnetic response in the form of the Semi-Meissner state. These systems cannot be categorised according to the Type-I/Type-II dichotomy (PRL 2010).

COLLABORATORS
Boris Svistunov UMASS, Amherst
Nikolay Prokof’ev UMASS, Amherst
Egor Babaev (Previous supervisor), KTH, Stockholm
Julien Garaud, University of Massachusetts, Amherst and KTH, Stockholm
Martin Speight, School of Mathematics, University of Leeds, UK
Mihail Silaev, IPM Russian Academy of Sciences and KTH, Stockholm