Fast and robust quantum control based on Pauli blocking

Abstract

Coherent quantum control over many-particle quantum systems requires high-fidelity dynamics. One way of achieving this is to use adiabatic schemeswhere the system follows an instantaneous eigenstate of the Hamiltonian over time scales that do not allow transitions to other states. This, however, makes control dynamics very slow. Here we introduce another concept that takes advantage of preventing unwanted transitions in fermionic systems by using Pauli blocking: excitations from a protected ground state to higher-lying states are avoided by adding a layer of buffer fermions, such that the protected fermions cannot make a transition to higher-lying excited states because these are already occupied. This allows us to speed up adiabatic evolutions of the system. We do a thorough investigation of the technique, and demonstrate its power by applying it to high-fidelity transport, trap expansion, and splitting in ultracold-atom systems in anharmonic traps. Close analysis of these processes also leads to insights into the structure of the orthogonality catastrophe phenomenon.