77 citations · 106 across the 13 of their papers we have counts for
13 papers
On quantum functionals for higher-order tensors
Alonso Botero, Matthias Christandl, Thomas C. Fraser +2
Upper and lower quantum functionals, introduced by Christandl, Vrana and Zuiddam (STOC 2018, J. Amer. Math. Soc. 2023), are families of monotone functions of tensors indexed by a w…
Plethysm is in #BQP
Matthias Christandl, Aram W. Harrow, Greta Panova +2
Some representation-theoretic multiplicities, such as the Kostka and the Littlewood-Richardson coefficients, admit a combinatorial interpretation that places their computation in t…
Computing moment polytopes -- with a focus on tensors, entanglement and matrix multiplication
Maxim van den Berg, Matthias Christandl, Vladimir Lysikov +3
Tensors are fundamental in mathematics, computer science, and physics. Their study through algebraic geometry and representation theory has proved very fruitful in the context of a…
The tetrahedral Horn problem and asymptotics of U(n) 6j symbols
Anton Alekseev, Matthias Christandl, Thomas C. Fraser
Horn's problem is concerned with characterizing the eigenvalues of Hermitian matrices satisfying the constraint and forming the edges of a triangle in t…
Explicit non-free tensors
Maxim van den Berg, Matthias Christandl, Vladimir Lysikov +3
Free tensors are tensors which, after a change of bases, have free support: any two distinct elements of its support differ in at least two coordinates. They play a distinguished r…
The moment polytope of matrix multiplication is not maximal
Maxim van den Berg, Matthias Christandl, Vladimir Lysikov +3
Moment polytopes of tensors, the study of which is deeply rooted in invariant theory, representation theory and symplectic geometry, have found relevance in numerous places, from q…
Asymptotic tensor rank is characterized by polynomials
Matthias Christandl, Koen Hoeberechts, Harold Nieuwboer +2
Asymptotic tensor rank is notoriously difficult to determine. Indeed, determining its value for the matrix multiplication tensor would determine the matrix multiplicati…
Making Existing Quantum Position Verification Protocols Secure Against Arbitrary Transmission Loss
Rene Allerstorfer, Andreas Bluhm, Harry Buhrman +4
Signal loss poses a significant threat to the security of quantum cryptography when the chosen protocol lacks loss-tolerance. In quantum position verification (QPV) protocols, even…
The Tensor as an Informational Resource
Matthias Christandl
A tensor is a multidimensional array of numbers that can be used to store data, encode a computational relation and represent quantum entanglement. In this sense a tensor can be vi…
Tip of the Quantum Entropy Cone
Matthias Christandl, Bergfinnur Durhuus, Lasse Harboe Wolff
Relations among von Neumann entropies of different parts of an -partite quantum system have direct impact on our understanding of diverse situations ranging from spin systems to…
A single-qubit position verification protocol that is secure against multi-qubit attacks
Andreas Bluhm, Matthias Christandl, Florian Speelman
The position of a device or agent is an important security credential in today's society, both online and in the real world. Unless in direct proximity, however, the secure verific…
Clean quantum and classical communication protocols
Harry Buhrman, Matthias Christandl, Christopher Perry +1
By how much must the communication complexity of a function increase if we demand that the parties not only correctly compute the function but also return all registers (other than…
Broadcast copies reveal the quantumness of correlations
M. Piani, M. Christandl, C. E. Mora +1
We study the quantumness of bipartite correlations by proposing a quantity that combines a measure of total correlations -- mutual information -- with the notion of broadcast copie…