Michael Walter
Contact: michael.walter@rub.de / Office: MC 1.89 / Tel: +49 (0)234 3228555
I am a full Professor of Computer Science and head of the Quantum Information group at the Faculty of Computer Science, RuhrUniversity Bochum and the CASA Cluster of Excellence.
My research is in quantum information and computation, and their interplay with other branches of computer science, mathematics, and theoretical physics. Motivated by quantum information, I also study problems in optimization, representation theory, and invariant theory through the lens of computation. I am a 2017 Veni laureate and received a 2020 Early Career Award from the Royal Netherlands Academy of Arts and Sciences (KNAW). We are part of the consortium project QuBRA and are also suported by an NWO OC ENW grant.
From 2017 to 2021, I was an Assistant Professor in Mathematics and Theoretical Physics at the University of Amsterdam (KdVI, ITFA, ILLC) and QuSoft. Before that, from 2014 to 2017, I was a Postdoctoral Scholar at Stanford University, hosted by Patrick Hayden. I received my PhD from ETH Zurich in October 2014 and was awarded an ETH Medal.
News

I am looking to hire several PhD students and postdocs to join us at Bochum. There will be official job advertisements soon, but please do not hesitate to get in touch if you are interested!

I gave a lecture series on Quantum Information at the 2021 AmsterdamBrusselsGenevaParis Doctoral School. See here for last yearâs slides.

I coorganized a workshop on âOptimization under Symmetryâ at the Simons Institute in Berkeley (Nov 29Dec 3, 2021).

Former postdoc Jonas Helsen is starting as a tenuretrack researcher at CWI. Congratulations, well deserved!

In NovDec 2021, we ran another edition of our web class for highschool students to learn about quantum computing â this year for the first time in collaboration with the African Institute for Mathematical Sciences. See here for more information about the The Quantum Quest.

I coorganized a workshop on âEfficient Tensor Representations for Learning and Computational Complexityâ at IPAM (May 1721).

In case you are looking for the slides of my talk on âPlaying games with quantum bitsâ at Leve de Wiskunde â21, please see here.

We are setting up a new specialization âDiscrete Mathematics and Quantum Informationâ in the MSc Mathematics (starting in fall 2021).

I am very honored to receive an Early Career Award by the Royal Netherlands Academy of Arts and Sciences (KNAW).

I gave lectures at TASI 2021 in June 2021. See here for video recordings: 1, 2, 3, 4

Stacey Jeffery and I are currently looking to hire a PhD student in quantum algorithms. For more information and to apply, see here. 
Together with Jay Armas, I organized a focus session on Information at all length scales: from black holes to quantum information and living systems at Physics@Veldhoven.

In Spring 2021 we will offer another edition of our MasterMath course Quantum Information Theory.

We ran another edition of our web class for highschool students to learn about quantum computing. See here for more information about the The Quantum Quest.

My grant proposal âTaming tensors: An optimization approach to computational invariant theoryâ was selected for funding by the NWO. Yay!

We organized a reading group âFrom Euclidean to Geodesic Convex Optimizationâ.

We organized a Lorentz Center workshop on âComplexity from Quantum Information to Black Holesâ from June 25
in Leidenonline! 
New preprint posted with colleagues from Google, Stanford, Caltech. We propose holographic teleportation protocols that are feasible for nearterm quantum computing platforms. See here for reporting.

I gave a lecture series on Quantum Information at the 14th Kavli Asian Winter School on Strings, Particles and Cosmology at Tohoku University in Jan 2020. Slides available here.

Together with Maris Ozols, I organized a web class for highschool students to learn about quantum computing. See here for more details about the 2018 edition of The Quantum Quest.

Together with Peter BĂŒrgisser, I organized a minisymposium on âEfficient algorithms for geometric invariant theoryâ at SIAMAG 2019. See here for details.

I recently visited the Science CafĂ© Nijmegen to discuss about spacetime tangled up in quantum information. See here and here for some impressions.

Together with Ankit Garg, Rafael Oliveira, and Avi Wigderson, I organized a workshop on scaling algorithms and applications at FOCS 2018. See here for details.

New article published in Communications of Mathematical Physics

New article published in PRX: popular summary & article
 New article published in PRX: popular summary & article
Group
 Valerie Bettaque (MSc project)
 Bjarne Bouwer (MSc project)
 Harold Nieuwboer (PhD candidate), classical & quantum optimization algorithms
 Galina Pass (PhD candidate), quantum algorithms
 Freek Witteveen (PhD candidate), quantum information & field theory
 Matteo Lostaglio (postdoc)
 Akshay Ramachandran (postdoc)
Alumni:
 Jonas Helsen (2019â21, postdoc; now tenuretrack researcher at CWI)
 Ricardo Rivera (202021; MSc project; soon PhD student at Slovak Academy of Sciences)
 Tomas Bosschieter (2021, BSc project on optimal transport and machine learning; now PhD student at Stanford)
 Friso Lohmann (2021, BSc project on quantum state tomography)
 Yinan Li (201820, postdoc; now designated assistant professor at Nagoya)
 Marten Folkertsma (201920, MSc project on continuous LOCC; now PhD student at CWI)
 Laurens Ligthard (201920, MSc project on quantum entropy; now PhD student at KĂ¶ln)
 Maxim van den Berg (2020, BSc project on lossless audio compression)
 Slawi Dimitrov (2020, BSc project on randomized benchmarking)
 Emma Loos (201819, MSc project on cMERA and holography; now PhD student at WĂŒrzburg)
 Jeroen Dekker (201819, MSc project on holographic tensor networks and smooth entropies)
 Lars van Geest (2019, BSc project on tensor networks for the Motzkin spin chain)
 John Paul Marceaux (2019, academic skills project on design theory)
 Philip Verduyn Lunel (201819, MSc project on quantum simulations and manybody localization; now PhD student at CWI)
 Raja Damanik (2018, MSc project on optimality in stabilizer testing; soon PhD student at Canberra)
 Casper Guyrik (2018, MSc project on quantum algorithms for factoring and postquantum RSA, daily supervised by Ronald de Wolf; now PhD student at Leiden)
 Philip Roeleveld (2018, BSc project on a truncated tensor scaling algorithm)
 Wouter Borg (2018, BSc project on entanglement in the stabilizer formalism)
Next group meeting: See Slack.
Publications and Preprints
See the arXiv and Google Scholar (and also GitHub).
Teaching
Fall 2021: Bachelorâs course Introduction to Information Theory [more]
Fall 2021: Master Seminar in Discrete Mathematics and Quantum Information
(a new specialization!)
Fall 2021: Master Seminar Theoretical Physics
Fall 2021: Web class Quantum Quest [more]
Spring 2021: MasterMath course Quantum Information Theory [more]
Fall 2020: Bachelorâs course Introduction to Information Theory [more]
Fall 2020: Master Seminar Theoretical Physics [more]
Fall 2020: Reading group From Euclidean to Geodesic Convex Optimization [more]
Fall 2020: Web class Quantum Quest [more]
Spring 2020: MasterMath course Quantum Information Theory [more]
Spring 2020: Master Seminar in Algebra, Geometry and Mathematical Physics
Spring 2020: Reading group From Euclidean to Geodesic Convex Optimization [more]
Fall 2019: New Bachelorâs course Introduction to Information Theory [more]
Fall 2019: Master Seminar in Algebra, Geometry and Mathematical Physics [more]
We read Bernd Sturmfelsâ book âAlgorithms in Invariant Theoryâ.
Fall 2019: Master Seminar Theoretical Physics [more]
Spring 2019: New MasterMath course Quantum Information Theory [more]
Spring 2019: Master Seminar in Algebra, Geometry and Mathematical Physics [more]
We read Saganâs book âThe Symmetric Groupâ.
Here is a refresher on basic representation theory roughly following Sections 1.1â1.6.
Fall 2018: Web class Quantum Quest [more]
Spring 2018: New Master course on Symmetry and Quantum Information [more]
I previously taught a similar course at Stanford University.
Watch this lecture as a teaser.
I also taught an abridged version of this course at IES in Cargese.
See here for introductory lectures on quantum information, field theory, and gravity (with an emphasis on links between these fields).
See here and here if you are looking for a Google Summer of Code project!
Quantum Software and Society
 Nature Insight
 Quantum software manifesto
 Ronald de Wolfâs essay on the impact of quantum computing on society
 John Preskillâs essay on noisy intermediatescale quantum technology
 Gatelevel quantum software platforms overview as of July 2018
Selected Talks
 âApproximate QCAs and a converse to the LiebRobinson boundsâ, Banff 2021 [pdf]
 âNoncommutative Group Symmetries and Optimizationâ, Oberwolfach 2021 [pdf]
 âHidden Symmetries II: Noncommutative Duality, Geodesic Convexity, Polytopesâ, Berkeley 2021 [pdf] [video]
 âQuantum BrascampLieb inequalitiesâ, IPAM 2021 [video], ICMP 2021 [pdf]
 âMaximum likelihood estimation for tensor normal modelsâ, Firenze 2021
 âFun with Replicas & Holographic Tensor Networksâ, Perimeter 2020 [video]
 âTensors, invariants, and optimizationâ, Leipzig 2019, Berkeley 2019, Berlin 2020, Chennai 2020, Perimeter 2020 [pdf] [pdf] [pdf] [pdf] [pdf]
 âQuantum circuits for the Dirac field in 1+1 dimensionsâ, AEI 2019, Stanford 2019, YITP 2019 [pdf] [video] [pdf] [pdf]
 âQuantum marginals, invariants, and noncommutative optimizationâ, Leiden 2019, SIAMAG 2019 [pdf] [pdf]
 âQuantum Marginals, Entanglement, and Symmetriesâ, DPG 2019 [pdf]
 âAn invitation to tensor networksâ, IAS 2018 [video]
 âQuantum Information and Holographyâ, DESY 2018 [pdf] [video]
 âSchurWeyl Duality for the Clifford Group: Property testing, de Finetti representations, and a robust Hudson theoremâ, QIP 2018, Boulder 2018, Bad Honnef 2018 [pdf] [video] [pdf] [pdf]
 âQuantum entanglement and spacetimeâ, Groningen 2018 [html] [video]
 âConvexity, marginals, and moment polytopesâ, IAS 2018 [pdf] [video]
 âIntroduction to Quantum Programmingâ, QuSoft 2018
 âQuantum marginal problem, tensor scaling, and invariant theoryâ, NMC 2018 [pdf]
 âRigorous entanglement renormalization from waveletsâ, KITP 2017, Caltech 2017, AEI 2018, Amsterdam 2018, GGI 2018 [pdf] [video] [pdf] [pdf] [pdf]
 âWhen is a quantum state a stabilizer state?â, QuSoft 2017, QuTech 2018 [pdf]
 âBulk reconstruction, error correction, and recovery mapsâ, KITP 2017 [video]
 âTensor network models of holographyâ, DESY 2017
 âWhen is a state a stabilizer state? Testing stabilizer states with six copiesâ, CWI 2017
 âTensors and Quantum Physicsâ, Auburn 2017 [video]
 âMultiparty entanglement, random codes, and quantum gravityâ, Coogee 2017 [pdf], âMultipartite entanglement in toy models of holographyâ, Simons Center for Geometry & Physics 2016 [pdf] [video]
 âEntanglement in random tensor networksâ, Georgia Tech 2016 [pdf]
 âHolographic duality from random tensor networksâ, MIT 2015, KITP 2016, Cologne 2016, IQC 2016 [pdf] [pdf] [video] [other]
 âMoment polytopes & computational complexityâ, Berkeley 2015 [pdf]
 âThe Holographic Entropy Coneâ, ETHZ, Caltech, CRM 2015; QIP 2016 [pdf short] [video] [pdf long]
 âKronecker coefficients and complexity theoryâ, Dartmouth 2015, Rome 2016 [pdf]
 âTopologically ordered models in higher dimensionsâ, QGQIT 2015 [pdf]
 âRandom Quantum Marginalsâ, IAS 2014 [video]
 âA Heisenberg Limit for Quantum Region Estimationâ, ISIT 2014 [pdf]
 âThe Quantum Marginal Problemâ, DPG Spring Meeting 2014 [pdf]
 âEntanglement Polytopesâ, QIP 2013; QSIT Lunch Seminar [pdf] [video] [science] [pdf] [explorer]
 âQuantum Entropies and Representation Theoryâ, IHES 2013 [pdf]
 âComputing Multiplicities of Lie Group Representationsâ, FOCS 2012 [pdf] [video]
 âQuantum State Tomography of 1000 Bosonsâ, SPS Meeting 2012 [pdf]
 âQuantum Marginals and Classical Momentsâ, IMS 2013 [pdf]
 âEigenvalue Distributions of Reduced Density Matricesâ, ICMP 2012 [pdf]
Software
 Solve the quantum marginal problem and compute entanglement polytopes using our new tensor scaling algorithm.
 Use wavelets to approximate ground states of free fermion theories.
 Prove new holographic entropy inequalities using the contractor
 Just a moment! â an algorithm for computing moment cones for the quantum marginal problem
 Explore entanglement polytopes
 Compute Kronecker coefficients using barvikron (Python) or the new Kronecker Maple package
 Download the quantum sandbox for Octave/Matlab
Other
 Amsterdam MathPhysics Colloquium
 Workshop on Quantum Marginals at the Isaac Newton Institute in Cambridge [photo]
 QCRYPT 2011 at ETH Zurich
 Career advice
 Quantum information conference calendar