25 January 2021

Space Science at Droptower SEMINAR TALK

Location: ZARM Bremen - Online seminar
When: 25.1.2021, 17:00 CET - Online

Speaker: Thomas Konrad (University of KwaZulu-Natal, Durban, South Africa)

Title: Robust control of quantum systems by quantum systems

Abstract: Quantum systems can be controlled by other quantum systems in
a reversible way, without any information leaking to the outside of the
system–controller compound. Such coherent quantum control is
deterministic, is less noisy than measurement-based feedback control,
and has potential applications in a variety of quantum technologies,
including quantum computation, quantum communication and quantum
metrology. In this talk I present a coherent feedback protocol,
consisting of a sequence of identical interactions with controlling
quantum systems, that steers a quantum system from an arbitrary initial
state towards a target state. I reveal the mechanism behind the control
and its relation to continuous monitoring of quantum systems.  A
theorem  determines the broad class of control channels that achieve
convergence to the target state, and then stabilise as well as protect
it against noise. The protocol can also be used to drive the system into
target dynamics. The information about the targets is encoded in the
controlling quantum systems and can be the result of a quantum
computation. In this way, we hope to achieve the basis for autonomous
control that entirely happens within the quantum realm without the need
to transform at any stage quantum information into classical information
by means of measurements.