Uploaded July 2026 | Updated September 2026, 2 weeks ago
Speaker: Michał Studziński (University of Gdańsk)
Abstract: Higher-order quantum operations describe transformations acting on quantum processes themselves, rather than only on quantum states. I will begin with the single-output setting, in which several uses of an unknown quantum operation are processed to produce one use of a target operation. I will also briefly outline extensions to the multicopy regime, where k input uses are converted into l output uses, and discuss the associated questions of physical realizability, optimal accuracy, and resource scaling. The main part of the talk will focus on the universal complex conjugation of an unknown finite-dimensional unitary transformation. Using symmetry arguments, representation theory, and semidefinite optimisation, we determine the optimal deterministic protocol for an arbitrary number of available input uses. The optimal strategy is parallel, requires no auxiliary memory system, and becomes exact when the number of available uses is one less than the dimension of the system.
Speaker: Michał Studziński (University of Gdańsk)
Abstract: Higher-order quantum operations describe transformations acting on quantum processes themselves, rather than only on quantum states. I will begin with the single-output setting, in which several uses of an unknown quantum operation are processed to produce one use of a target operation. I will also briefly outline extensions to the multicopy regime, where k input uses are converted into l output uses, and discuss the associated questions of physical realizability, optimal accuracy, and resource scaling. The main part of the talk will focus on the universal complex conjugation of an unknown finite-dimensional unitary transformation. Using symmetry arguments, representation theory, and semidefinite optimisation, we determine the optimal deterministic protocol for an arbitrary number of available input uses. The optimal strategy is parallel, requires no auxiliary memory system, and becomes exact when the number of available uses is one less than the dimension of the system.
