University College Cork
Physics Department
Quantum Optics: Shortcuts to Adiabaticity

This is the home page of the research group of Dr. Andreas Ruschhaupt, based in the Physics Department at the University College Cork (Ireland).

Latest Publications of the Group
A. Ruschhaupt, T. Dowdall, M. A. Simón, J. G. Muga, Asymmetric scattering by non-hermitian potentials, arXiv:1709.07027

The scattering of quantum particles by non-hermitian (generally nonlocal) potentials in one dimension may result in asymmetric transmission and/or reflection from left and right incidence. Eight generalized symmetries based on the discrete Klein's four-group (formed by parity, time reversal, their product, and unity) are used together with generalized unitarity relations to determine the possible and/or forbidden scattering asymmetries. Six basic device types are identified when the scattering coefficients (squared moduli of scattering amplitudes) adopt zero/one values, and transmission and/or reflection are asymmetric. They can pictorially be described as a one-way mirror, a one-way barrier (a Maxwell pressure demon), one-way (transmission or reflection) filters, a mirror with unidirectional transmission, and a transparent, one-way reflector. We design potentials for these devices and also demonstrate that the behavior of the scattering coefficients can be extended to a broad range of incident momenta.

Tom Dowdall, Albert Benseny, Thomas Busch, Andreas Ruschhaupt, Quantum Coherent Control via Pauli Blocking, arXiv:1705.04559, Phys. Rev. A, in print

Coherent quantum control over many-particle quantum systems requires high fidelity dynamics. One way of achieving this is to use adiabatic schemes where the system follows an instantaneous eigenstate of the Hamiltonian over timescales 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 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 atoms systems in anharmonic traps. Close analysis of these processes also leads to insights into the structure of the orthogonality catastrophe phenomenon.

Past Events
Anthony's Thesis Defense (January 2017)
Congratulations Anthony!
[Anthony's defence]

Summer school (July 2016)
Summer School:
Shortcut to Adiabaticity 2016
in Cork (UCC)

Monday 25th and Tuesday 26th July 2016 (two full days)

International Speakers:
J. Gonzalo Muga (UPV, Bilbao, Spain)
Andrea Alberti (University of Bonn, Germany)
Thomas Busch (OIST, Japan)
Local Speaker and Organiser:
Andreas Ruschhaupt (UCC)
Local Co-Organiser:
David Rea (UCC)
Programme (final):
[STA 2016 Group Photo]

From left to right: David Rea, Henry O'Keeffe,Shane O'Mahony, Amy Kirwan, Tom Dowdall, Chris Whitty, John Brennan, Brian O'Sullivan, Kevin Shortiss, Guido de Rosa, Ciaran Deasy, Kieran Cooney, Steve Campbell, Andreas Ruschhaupt, Thomas Busch, Pramod Kumar, Andrea Alberti, Gonzalo Muga and Anthony Kiely.