InstituteQ Colloquium: Professor Jakub Tworzydło

This InstituteQ Colloquium features Professor Jakub Tworzydło from the University of Warsaw. The title of his talk is “The necessity of complex numbers in quantum theory: Experimental evidence.”

Jakub Tworzydło studied physics at the University of Warsaw (Poland), where he received his PhD in Theoretical Physics in 1995. Following postdoctoral research at Leiden University in the Netherlands, including a Marie Curie Fellowship, he returned to the University of Warsaw, where he held various academic positions before being appointed as a full professor in 2014. He has also held visiting research positions supported by the Netherlands Science Foundation, participating in several European research consortia including the ERC and QuanERA programmes. His research lies in the field of condensed matter theory, particularly quantum transport, topological phases of matter and mesoscopic systems, for which he uses analytical techniques and numerical models.

Event details

When: 14.00-15.00, 24.6.2025
Where: Lecture Hall V001, Ekonominaukio 1, 02150 Espoo
Register: Webropol link to register
Host: Aalto University Physics Professor Pertti Hakonen

From Jakub Tworzydło: What will your talk discuss?

The fundamental role of complex numbers in quantum theory has long been the subject of debate. While complex numbers are essential in the mathematical formulation of quantum mechanics, one may wonder whether they are really necessary to describe physical phenomena. Recent research has proposed that a ‘true quantum theory’ can in principle be formulated using only real numbers, at the expense of increasing the dimension of the Hilbert space. Such a theory could reproduce the results of entanglement experiments, using real operators. However, it turns out that the complex and real formulations of quantum theory give different predictions in certain quantum information processing scenarios.

In this lecture, I will discuss how our research has taken this further by designing a Bell-type experiment that can effectively distinguish between real and composite quantum theories. Our results, obtained with experiments on the IBM quantum platform, show a significant violation of the constraint imposed by the real theory. Thus, we obtain strong evidence for the necessity of using complex numbers in the description of physical phenomena.