Research @ Faculty of Science 2023

DEPARTMENT OF APPLIED MATHEMATICS 97 Email raymond.sze@polyu.edu.hk Qualification BSc (The University of Hong Kong) MPhil (The University of Hong Kong) PhD (The University of Hong Kong) ORCID ID 0000-0003-1567-2654 Dr SZE Nung-sing Raymond Associate Professor Associate Dean of Faculty of Science Research Overview Dr Sze’s current research interests are in the area of quantum information science, specifically the related mathematical problems in matrix and operator theory. Research topics involve quantum error correction, quantum entanglement, and generalised numerical ranges. Other topics of interest include sensitivity analysis in nonnegative matrix theory and preserver problems. Representative Publications • P.S. Lau, C.K. Li, Y.T. Poon, N.S. Sze, Convexity and starshapedness of matricial range. J. Funct. Anal. 275:2497-2515, 2018 • C.K. Li, M. Nakahara, Y.T. Poon, N.S. Sze, Maximal noiseless code rates for collective rotation channels on qudits. Quantum Inf. Process 14:4039-4055, 2015 • U. Gungordu, C.K. Li, M. Nakahara, Y.T. Poon, and N.S. Sze, Recursive encoding and decoding of the noiseless subsystem for qudits. Phys. Rev. A 89:042301, 2014 • CK. Li and N.S. Sze, Determinantal and eigenvalue inequalities for matrices with numerical ranges in a sector. J. Math. Anal. Appl. 410:487-491, 2014 • C.K. Li, M. Nakahara, Y.T. Poon, N.S. Sze, and H. Tomita, Recovery in quantum error correction for general noise without measurement. Quantum Inf Comput. 12:149-158, 2012 • H.L. Gau, C.K. Li, Y.T. Poon, and N.S. Sze, Higher rank numerical ranges of normal matrices. SIAM J. Matrix Analysis Appl. 32:23-43, 2011 • M. Catral, S.J. Kirkland, M. Neumann, and N.S. Sze, The Kemeny constant for finite homogeneous ergodic Markov chains. J. Sci. Comput 45:151-166, 2010 • C.K. Li, N.S. Sze, Canonical forms, higher rank numerical ranges, totally isotropic subspaces, and matrix equations. Proc. Amer. Math. Soc. 136: 3013-3023, 2008 • S.J. Kirkland, M. Neumann, and N.S. Sze, On optimal condition numbers for Markov chains. Numer. Math. 110:521-537, 2008 • J.T. Chan, C.K. Li, and N.S. Sze, Mappings preserving spectra of product of matrices. Proc. Amer. Math. Soc. 135:977–986, 2007 Award • Journal of Mathematical Analysis and Applications (JMAA) Ames Award, 2014 Encoding and recovery circuits, which encode and recover an arbitrary (n − 2)-qubit state ρ with two ancilla qubit initially in the state |00><00|. The circuit (a) is for n = 4 while (b) is for n = 6. The quantum channel in the box represents a quantum operation with fully correlated noise. Experimentally measured data (red dots) and the theoretical predictions of Joint numerical range (chromatic convex bodies) for the examples of the eight possible classes.

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