Pieter W. Claeys



Visiting UNB

26 August 2019

This week I'll be visiting the University of New Brunswick in Canada, visiting the De Baerdemacker group and talking to a crowd of unexpecting chemists about transitionless driving in quantum many-body systems.

Conferences: DYNQOS19 & Lindau

16 June 2019

Catch me in Germany this month - next week, I am attending the Engineering Nonequilibrium Dynamics of Open Quantum Systems (DYNQOS19) workshop at the Max Planck Institute in Dresden. On Tuesday, I will be talking about our recent results on Floquet-engineering counterdiabatic protocols in quantum many-body systems, and on Thursday I will be chairing the late afternoon session. More information about the program here.

After this conference, on to the next, since I will also be presenting this topic as a poster at the 69th Lindau Nobel Laureate Meeting (see above)!

Counterdiabatic driving, adiabatic gauge potentials, and Floquet-engineering

09 April 2019

Publication news - our preprint about counterdiabatic driving in quantum many-body systems has appeared on arXiv! A new topic for me, albeit with some interesting connections with my Ph.D. research. Joint work with Mohit Pandey, Dries Sels, and Anatoli Polkovnikov.

When changing a system from state A to state B, this is usually done extremely slow (adiabatically), carefully attempting not to disturb the system. However, in practice we can't take arbitrarily long due to system constraints, external noise,... One interesting way of speeding up such processes is through counterdiabatic driving, where we explicitly counteract the forces arising when changing a system a finite rate. However, it is generally extremely hard to (a) know what forces to apply and (b) know how to realize these forces. Mathematically, everything is encoded in the adiabatic gauge potential, and in this preprint we show how this potential can be approximated in a surprisingly accurate way and how the resulting forces and counterdiabatic driving can be realized through a 'simple' shaking of the system.

Floquet-engineering counterdiabatic protocols in quantum many-body systems: Counterdiabatic (CD) driving presents a way of generating adiabatic dynamics at arbitrary pace, where excitations due to non-adiabaticity are exactly compensated by adding an auxiliary driving term to the Hamiltonian. While this CD term is theoretically known and given by the adiabatic gauge potential, obtaining and implementing this potential in many-body systems is a formidable task, requiring knowledge of the spectral properties of the instantaneous Hamiltonians and control of highly nonlocal multibody interactions. We show how an approximate gauge potential can be systematically built up as a series of nested commutators, remaining well-defined in the thermodynamic limit. Furthermore, the resulting CD driving protocols can be realized up to arbitrary order without leaving the available control space using tools from periodically-driven (Floquet) systems. This is illustrated on few- and many-body quantum systems, where the resulting Floquet protocols significantly suppress dissipation and provide a drastic increase in fidelity.