# Distinguished Lectures on Quantum Software

Featuring an all-star line-up, the first edition of QuSoft’s Distinguished Lectures on Quantum Software will take place on 14 March 2019. Experts from throughout the field of quantum cryptology and quantum foundations will share their views and expertise.

Notable for his pioneering work on quantum informatics, Gilles Brassard (Université de Montréal) will discuss his recent breakthroughs. Brassard has made remarkable progress in aligning quantum theory with Albert Einstein’s perspective on local realism – with no need for what Einstein colorfully dismissed as ‘spooky action at a distance’. During his lecture, Brassard will discuss how quantum theory can be completed, including entanglement, but without resorting to nonlocality, Bell’s theorem notwithstanding.

Brassard is regarded by many as one of the founding fathers of quantum informatics. In 2018, Brassard won the prestigious Wolf Prize in Physics for his contribution to the creation and development of quantum cryptography and quantum teleportation. Currently, Brassard is a visiting scientist at QuSoft, the Dutch research center for quantum software.

PROGRAM

12.45-13.15

Registration

13.15-13.30

Opening

13.30-14.10

Christian Schaffner (UvA/CWI/QuSoft)

*"The Quantum-Random-Oracle Model"*

14.10-14.50

Nicolas Gisin (University of Geneva)

*"Quantum Non-Locality in Networks"*

Quantum non-locality, i.e. the violation of some Bell inequality, has proven to be an extremely useful concept in analyzing entanglement, quantum randomness and cryptography, among others. In particular, it led to the fascinating field of device-independent quantum information processing.

Historically, the idea was that the particles emitted by various quantum sources carry additional variables, known as local hidden variables. The more modern view, strongly influenced by computer science, refers to these additional variables merely as shared randomness. This, however, leads to ambiguity when there is more than one source, as in quantum networks. Should the randomness produced by each source be considered as fully correlated, as in most common analyses, or should one analyze the situation assuming that each source produces independent randomness, closer to the historical spirit?

The latter is known, for the case of n independent sources, as n-locality. For example, in entanglement swapping there are two sources, hence “quantumness” should be analyzed using 2-locality (or, equivalently, bi-locality). The situation when the network has loops is especially interesting. Recent results for triangular networks will be presented.

14.50-15.30

Break for coffee/tea

15.30-16.10

Renato Renner (ETH Zürich)

*"Quantum theory cannot consistently describe the use of itself"*

Can quantum mechanics be used to describe a physicist who herself uses quantum mechanics? Clearly, if quantum mechanics was a universally valid physical theory, the answer should be yes. In my talk, I will present an extension of Schrödinger’s cat thought experiment, with the cat replaced by a quantum physicist (or, maybe preferably, a computer that is programmed to make predictions based on the laws of quantum physics). This allows us to provide an answer to the question posed above.

The talk is based on the recent paper "Quantum theory cannot consistently describe the use of itself” by Frauchiger and Renner (Nature Communications 9, 3711, 2018).16.10-16.50

16.10-16.50

Stacey Jeffery (CWI/QuSoft)

*"Quadratic speedup for finding marked vertices by quantum walks"*

A quantum walk algorithm can detect the presence of a marked vertex on a graph quadratically faster than the corresponding random walk algorithm (Szegedy, FOCS 2004). However, quantum algorithms that actually find a marked element quadratically faster than a classical random walk were only known for the special case when the marked set consists of just a single vertex, or in the case of some specific graphs. We present a new quantum algorithm for finding a marked vertex in any graph, with any set of marked vertices, quadratically faster than the corresponding classical random walk.

This is joint work with Andris Ambainis, András Gilyén, and Martins Kokainis.

16.50-17.30

Gilles Brassard (University of Montreal)

*"Could Einstein have been right after all?"*

*One of the most surprising aspects of quantum theory is that it tells us that we live in a nonlocal universe. This idea was completely abhorrent to Einstein, who dismissed it as "spooky action at a distance". Recent so-called loophole-free experiments (the first one having been performed in the Netherlands) have confirmed nonlocality beyond any reasonable doubt. But have they really? In this talk, I shall argue that no experiment whose purpose is to confirm the predictions of quantum theory can possibly be used as an argument in favour of nonlocality because any theory of physics that does not allow instantaneous signalling to occur and has reversible dynamics (such as unitary quantum theory) can be explained in a purely local and realistic universe. And if Einstein was right after all... once again?
(This is joint work with Paul Raymond-Robichaud)*

17.30-17.40

Closing

17.40-18.40

Drinks

**REGISTRATION**

Participation is free after registration.

Registration is mandatory!

You can register by email to office@quantumsc.nl.

Please mention your name and your affiliation.

We warmly welcome you to attend this event. Your presence is highly appreciated.

Please be so kind to forward this event to your group members or others involved in quantum research.