Hi all,
today we're meeting a little bit early so that those interested can also
make it to the Robert Wald lecture downtown later (see here:
http://www.eth-its.ethz.ch/activities/its-science-colloquium/Robert%20Wald.…).
Christa Zoufal will present the results of her master's thesis. See below
for title and abstract.
Best,
-joe
Title:
The quantum SWITCH and its causal simulations
Abstract:
Quantum mechanics challenges our intuition in a wide range of areas. In
particular, the superposition principle leads to a large number of
counterintuitive phenomena. Recently, it was found that it allows for
scenarios where the order of the events can be in a quantum superposition.
The first example of this situation is the quantum SWITCH, a higher-order
operation that combines two gates in an order that is determined by the
state of a quantum system. It has been shown that the SWITCH offers
advantages in communication and computation. However, to achieve these
advantages, one has to implement the quantum SWITCH in a real physical
system. Since in standard quantum mechanics the order of events is
well-defined, it is natural to ask in which sense an experimental
implementation realizes an indefinite causal order. The aim of this thesis
is to determine the resources needed for the simulation of the quantum
SWITCH in a definite causal order, analyzing different types of simulations
and showing that every simulation of the quantum SWITCH on generic boxes
requires extra resources, such as the addition of quantum control and
communication channels, and the use of multiple copies of the controlled
boxes.