About
Contact: hani@math.ku.dk (previous email address: h.a.nieuwboer@uva.nl, may become inactive soon)
I am currently a postdoctoral researcher at QMATH at the University of Copenhagen, advised by prof. dr. Matthias Christandl and dr. Laura Mančinska. Formerly, I was a PhD student at the Kortewegde Vries Institute and QuSoft at the University of Amsterdam, and an affiliated researcher at the RuhrUniversität Bochum, advised by prof. dr. Michael Walter and prof. dr. Eric Opdam.
I’m interested in classical and quantum algorithms for optimization problems with a lot of geometric or algebraic structure, such as (geodesic) convexity or having many symmetries. In particular, I have worked on scaling problems, such as matrix scaling, operator scaling and tensor scaling. These problems have connections to representation theory, geometric invariant theory, quantum information theory, quantum manybody physics, machine learning, statistics, and numerical linear algebra.
Papers

Interiorpoint methods on manifolds: theory and applications
H. Hirai, H. Nieuwboer and M. Walter
FOCS (2023), arXiv:2303.04771 (2023) 
Basic quantum subroutines: finding multiple marked elements and summing numbers
J. van Apeldoorn, S. Gribling, and H. Nieuwboer
arXiv:2302.10244 (2023) 
The minimal canonical form of a tensor network
A. Acuaviva, V. Makam, H. Nieuwboer, D. PérezGarcía, F. Sittner, M. Walter and F. Witteveen
FOCS (2023), QIP, short plenary talk (2023), arXiv:2209.14358 (2022) 
Improved Quantum Lower and Upper Bounds for Matrix Scaling
S. Gribling and H. Nieuwboer
STACS (2022), arXiv:2109.15282 (2021) 
Quantum Algorithms for Matrix Scaling and Matrix Balancing
J. van Apeldoorn, S. Gribling, Y. Li, H. Nieuwboer, M. Walter, and R. de Wolf
ICALP (2021), TQC (2021), arXiv:2011.12823 (2020) 
Interiorpoint methods for unconstrained geometric programming and scaling problems
P. Bürgisser, Y. Li, H. Nieuwboer, and M. Walter
arXiv:2008.12110 (2020) 
An Extended TwinPedigree Study of Neuroticism in the Netherlands Twin Register
D. I. Boomsma, Q. Helmer, H. A. Nieuwboer, J. J. Hottenga, M. H. de Moor, S. M. van den Berg, G. E. Davies, J. M. Vink, M. J. Schouten, C. V. Dolan, G. Willemsen, M. Bartels, T. C. E. M. van Beijsterveldt, L. Ligthart, and E. J. de Geus
Behavior Genetics (2018) 
GWIS: GenomeWide Inferred Statistics for Functions of Multiple Phenotypes
H. A. Nieuwboer, R. Pool, C. V. Dolan, D. I. Boomsma, and M. G. Nivard
American Journal of Human Genetics (2016) 
The Computerized Neurocognitive Battery: Validation, aging effects, and heritability across cognitive domains
S. C. Swagerman, E. J. C. de Geus, K.J. Kan, E. van Bergen, H. A. Nieuwboer, M. M. G. Koenis, H. E. Hulshoff, Pol, R. E. Gur, R. C. Gur, and D. I. Boomsma
Neuropsychology (2016)