Felix Huber
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View article: Refuting spectral compatibility of quantum marginals
Refuting spectral compatibility of quantum marginals Open
The spectral variant of the quantum marginal problem asks: Given prescribed spectra for a set of overlapping quantum marginals, does there exist a compatible joint state? The main idea of this work is a symmetry-reduced semidefinite progra…
View article: Quasi-Clifford to qubit mappings
Quasi-Clifford to qubit mappings Open
Algebras with given (anti-)commutativity structure are widespread in quantum mechanics. This structure is captured by quasi-Clifford algebras (QCA): a QCA generated by $α_1, \dots, α_n$ is is given by the relations $α_i^2 = k_i$ and $α_j α…
View article: On two maximally entangled couples
On two maximally entangled couples Open
In a seminal article, Higuchi and Sudbery showed that a pure four-qubit state can not be maximally entangled across every bipartition. Such states are now known as absolutely maximally entangled (AME) states. Here we give a series of old a…
View article: What about the heart — pediatric ALL survivors show cardiopulmonary limitations in the MinimALL Study
What about the heart — pediatric ALL survivors show cardiopulmonary limitations in the MinimALL Study Open
Childhood survivors of acute lymphoblastic leukemia (ALL) and Hodgkin disease (HD) are at risk of long-term cardiopulmonary impairments due to cardiotoxic chemotherapy and inactivity. This study aims to assess the cardiopulmonary fitness a…
View article: Positivity of state, trace, and moment polynomials, and applications in quantum information
Positivity of state, trace, and moment polynomials, and applications in quantum information Open
State, trace, and moment polynomials are polynomial expressions in several operator or random variables and positive functionals on their products (states, traces or expectations). While these concepts, and in particular their positivity a…
View article: Second order cone relaxations for quantum Max Cut
Second order cone relaxations for quantum Max Cut Open
Quantum Max Cut (QMC), also known as the quantum anti-ferromagnetic Heisenberg model, is a QMA-complete problem relevant to quantum many-body physics and computer science. Semidefinite programming relaxations have been fruitful in designin…
View article: SDP bounds on quantum codes
SDP bounds on quantum codes Open
This paper provides a semidefinite programming hierarchy based on state polynomial optimization to determine the existence of quantum codes with given parameters. The hierarchy is complete, in the sense that a $(\!(n, K, δ)\!)_2$ code exis…
View article: Author Correction: Engineering holography with stabilizer graph codes
Author Correction: Engineering holography with stabilizer graph codes Open
The discovery of holographic codes established a surprising connection between quantum error correction and the anti-de Sitter-conformal field theory correspondence.Recent technological progress in artificial quantum systems renders the ex…
View article: Engineering holography with stabilizer graph codes
Engineering holography with stabilizer graph codes Open
The discovery of holographic codes established a surprising connection between quantum error correction and the anti-de Sitter-conformal field theory correspondence. Recent technological progress in artificial quantum systems renders the e…
View article: Uncertainty relations from state polynomial optimization
Uncertainty relations from state polynomial optimization Open
Uncertainty relations are a fundamental feature of quantum mechanics. How can these relations be found systematically? Here we develop a semidefinite programming hierarchy for additive uncertainty relations in the variances of non-commutin…
View article: Bell Inequalities with Overlapping Measurements
Bell Inequalities with Overlapping Measurements Open
We thank Armin Tavakoli for
\nfeedback on the manuscript and Pawe l Horodecki for
\nfruitful discussions. MBM and FH were supported
\nby the FNP through TEAM-NET (POIR.04.04.00-
\n00-17C1/18-00). APK’s work is supported by
\nthe Spanish Mi…
View article: Arbor Library v0.9.0
Arbor Library v0.9.0 Open
v0.9.0 ** 2023 08 09 ** After much more delay than anticipated, we are very happy to present a new Arbor release. Nearly 8 months of work is in it, much of which focussed on speed, optimisation, fixes and build system changes. This release…
View article: Entanglement detection with trace polynomials
Entanglement detection with trace polynomials Open
We provide a systematic method for nonlinear entanglement detection based on trace polynomial inequalities. In particular, this allows to employ multi-partite witnesses for the detection of bipartite states, and vice versa. We identify wit…
View article: Bell inequalities with overlapping measurements
Bell inequalities with overlapping measurements Open
Which nonlocal correlations can be obtained, when a party has access to more than one subsystem? While traditionally nonlocality deals with spacelike separated parties, this question becomes important with quantum technologies that connect…
View article: Quantum error-correcting codes and their geometries
Quantum error-correcting codes and their geometries Open
This is an expository article aiming to introduce the reader to the underlying mathematics and geometry of quantum error correction. Information stored on quantum particles is subject to noise and interference from the environment. Quantum…
View article: 3D homogenization of the T-A formulation for the analysis of coils with complex geometries
3D homogenization of the T-A formulation for the analysis of coils with complex geometries Open
The modeling and analysis of superconducting coils is an essential task in the design stage of most devices based on high-temperature superconductors (HTS). These calculations allow verifying basic estimations and assumptions, proposing im…
View article: Engineering holography with stabilizer graph codes
Engineering holography with stabilizer graph codes Open
The discovery of holographic codes established a surprising connection between quantum error correction and the anti-de Sitter-conformal field theory correspondence. Recent technological progress in artificial quantum systems renders the e…
View article: 3D homogenization of the T-A formulation for the analysis of coils with complex geometries
3D homogenization of the T-A formulation for the analysis of coils with complex geometries Open
The modeling and analysis of superconducting coils is an essential task in the design stage of most devices based on high-temperature superconductors (HTS). These calculations allow verifying basic estimations and assumptions, proposing im…
View article: Evidence-based indicators for the measurement of quality of primary care using health insurance claims data in Switzerland: update of the SQUIPRICA working group
Evidence-based indicators for the measurement of quality of primary care using health insurance claims data in Switzerland: update of the SQUIPRICA working group Open
Background The level of quality of care of ambulatory services in Switzerland is almost completely unknown. Since health insurance claims are the only nationwide applicable and available data source for this purpose, a set of 24 quality in…
View article: Training Characteristic Functions with Reinforcement Learning: XAI-methods play Connect Four
Training Characteristic Functions with Reinforcement Learning: XAI-methods play Connect Four Open
One of the goals of Explainable AI (XAI) is to determine which input components were relevant for a classifier decision. This is commonly know as saliency attribution. Characteristic functions (from cooperative game theory) are able to eva…
View article: Entropic Proofs of Singleton Bounds for Quantum Error-Correcting Codes
Entropic Proofs of Singleton Bounds for Quantum Error-Correcting Codes Open
We show that a relatively simple reasoning using von Neumann entropy inequalities yields a robust proof of the quantum Singleton bound for quantum error-correcting codes (QECC). For entanglement-assisted quantum error-correcting codes (EAQ…
View article: The T-A formulation: an efficient approach to model the macroscopic electromagnetic behaviour of HTS coated conductor applications
The T-A formulation: an efficient approach to model the macroscopic electromagnetic behaviour of HTS coated conductor applications Open
In recent years, the T-A formulation has emerged as an efficient approach for modelling the electromagnetic behaviour of high-temperature superconductor (HTS) tapes in the form of coated conductors (CCs). HTS CCs are characterized by an ex…
View article: Positive maps from the walled Brauer algebra
Positive maps from the walled Brauer algebra Open
We present positive maps and matrix inequalities for variables from the positive cone. These inequalities contain partial transpose and reshuffling operations, and can be understood as positive multilinear maps that are in one-to-one corre…
View article: Reduced ice number concentrations in contrails from low-aromatic biofuel blends
Reduced ice number concentrations in contrails from low-aromatic biofuel blends Open
Sustainable aviation fuels can reduce contrail ice numbers and radiative forcing by contrail cirrus. We measured apparent ice emission indices for fuels with varying aromatic content at altitude ranges of 9.1–9.8 and 11.4–11.6 km. Measurem…
View article: Conjugate Logic.
Conjugate Logic. Open
We propose a conjugate logic that can capture the behavior of quantum and quantum-like systems. The proposal is similar to the more generic concept of epistemic logic: it encodes knowledge or perhaps more correctly, predictions about outco…
View article: Universal quantum computation and quantum error correction with ultracold atomic mixtures
Universal quantum computation and quantum error correction with ultracold atomic mixtures Open
Quantum information platforms made great progress in the control of many-body entanglement and the implementation of quantum error correction, but it remains a challenge to realize both in the same setup. Here, we propose a mixture of two …