sjgarratt(at)berkeley.edu
arXiv
Google Scholar
I am a theoretical physicist at Princeton University. My interests are in many-body quantum mechanics and the interface between quantum and classical simulation. Here there are connections to be made between statistical mechanics, quantum information, and conventional condensed matter physics.
Recently, a set of problems that I have been focusing on concern the effects that measurements have on many-body quantum systems. These effects are practically relevant to quantum error correction, and to our understanding of the complexity of simulating quantum systems on classical computers. You can find a detailed explanation in this talk (from Simons Center, Berkeley), and an even more detailed explanation in this talk (from Cornell). Our most recent work on this can be found on arXiv. There, using Google's superconducting quantum processors, we showed that measurement-induced collective phenomena can be detected in 'snapshots' of quantum states.
This summer (2025) I gave a lecture series at Berkeley as part of the NSF Challenge Institute for Quantum Computation (CIQC). There was also a livestream. The course covers the basics of quantum computation, starting from the perspective of quantum dynamics. The target audience is early graduate students in physics and chemistry, and only assumes a familiarity with basic quantum mechanics. Here are the notes.
Preprints
https://arxiv.org/abs/2509.08890
Machine learning the effects of many quantum measurements
Wanda Hou, Samuel J. Garratt, Norhan M. Eassa, Eliott Rosenberg, Pedram Roushan, Yi-Zhuang You, Ehud Altman
Learning transitions in classical Ising models and deformed toric codes
Malte Pütz, Samuel J. Garratt, Hidetoshi Nishimori, Simon Trebst, Guo-Yi Zhu
https://arxiv.org/abs/2502.13218
Entanglement and private information in many-body thermal states
Samuel J. Garratt, Max McGinley
https://arxiv.org/abs/2501.09084
Goldstone mode of the broken helix in U(1) magnet EuIn2As2
Alex Liebman-Pelaez, Samuel J. Garratt, Veronika Sunko, Yue Sun, Jian R. Soh, Dharmalingam Prabhakaran, Andrew T. Boothroyd, Joseph Orenstein
Post-measurement quantum Monte Carlo
Kriti Baweja, David J. Luitz, Samuel J. Garratt
https://arxiv.org/abs/2407.07893
Quantum Algorithm to Prepare Quasi-Stationary States
Samuel J. Garratt, Soonwon Choi
Publications
Phys. Rev. B 112, 054436 (2025)
https://arxiv.org/abs/2502.09612
Superspin renormalization and slow relaxation in random spin systems
Yi J. Zhao, Samuel J. Garratt, Joel Moore
Phys. Rev. B 111, 094316 (2025)
https://arxiv.org/abs/2312.14234
Operator dynamics in Floquet many-body systems
Takato Yoshimura, Samuel J. Garratt, J. T. Chalker
Phys. Rev. X Quantum 5, 030311 (2024)
https://arxiv.org/abs/2305.20092
Probing post-measurement entanglement without post-selection
Samuel J. Garratt, Ehud Altman
Phys. Rev. B 107, 245132 (2023) https://arxiv.org/abs/2301.08268
Nonlocality and entanglement in measured critical quantum Ising chains
Zack Weinstein, Rohith Sajith, Ehud Altman, Samuel J. Garratt
Phys. Rev. X 13, 021026 (2023) https://arxiv.org/abs/2207.09476
Measurements conspire nonlocally to restructure critical quantum states
Samuel J. Garratt, Zack Weinstein, Ehud Altman
Phys. Rev. B 106, 054309 (2022) https://arxiv.org/abs/2202.10482
Resonant energy scales and local observables in the many-body localized phase
Samuel J. Garratt, Sthitadhi Roy
Phys. Rev. A 106, 012441 (2022) https://arxiv.org/abs/2202.05132
Quantifying information scrambling via Classical Shadow Tomography on Programmable Quantum Simulators
Max McGinley, Sebastian Leontica, Samuel J. Garratt, Jovan Jovanovic, Steven H. Simon
Phys. Rev. B 104, 184203 (2021) https://arxiv.org/abs/2107.12387
Local resonances and parametric level dynamics in the many-body localised phase
S. J Garratt, Sthitadhi Roy, J. T. Chalker
Phys. Rev. Lett. 127, 026802 (2021) https://arxiv.org/abs/2012.11580
Many-body delocalisation as symmetry breaking
S. J Garratt, J. T. Chalker
Phys. Rev. X 11, 021051 (2021) https://arxiv.org/abs/2008.01697
Local pairing of Feynman histories in many-body Floquet models
S. J. Garratt, J. T. Chalker
Phys. Rev. Lett. 126, 060402 https://arxiv.org/abs/2004.11363
Many-body Decay of the Gapped Lowest Excitation of a Bose-Einstein Condensate
Jinyi Zhang, Christoph Eigen, Wei Zheng, Jake A. P. Glidden, Timon A. Hilker, Samuel J. Garratt, Raphael Lopes, Nigel R. Cooper, Zoran Hadzibabic, Nir Navon
Phys. Rev. B 101, 024413 (2020) https://arxiv.org/abs/1908.02271
Goldstone modes in the emergent gauge fields of a frustrated magnet
Samuel J. Garratt, J. T. Chalker
Phys. Rev. A 99, 021601(R) (2019) https://arxiv.org/abs/1810.08195
From single-particle excitations to sound waves in a box-trapped atomic Bose-Einstein condensate
Samuel J. Garratt, Christoph Eigen, Jinyi Zhang, Patrik Turzák, Raphael Lopes, Robert P. Smith, Zoran Hadzibabic, Nir Navon
Research & before
2025 - now: Associate Research Scholar in Princeton
2021 - 2025: Moore Fellowship in Berkeley, working with Ehud Altman and Joel Moore.
2017 - 2021: DPhil from Oxford, working with John Chalker.
2013 - 2017: BA + MSci from Cambridge, with research in the group of Zoran Hadzibabic.
Teaching
Sep. 21 - now: advising undergraduate and graduate research students.
Oct. 19 - Sep. 21: stipendiary lecturer at St. Hugh's College, Oxford, for MPhys.
Sep. 18 - Jan. 19: class tutor/organiser for Oxford MMathPhys.
Jan. 18 - Oct. 19: tutor at St. Hugh's College, Oxford, for MPhys.
Recent Talks
Caltech - July 25
King's College London - Apr 25
ETH Zurich - Apr 25
IST Austria - Jan 25
University of Cambridge - Jan 25
University of Manchester - Aug 24
IST Austria - Jul 24
University of New Mexico - Apr 24
University of Cambridge - Mar 24
University of Cologne - Mar 24
PKS Dresden, Quantum Interactive Dynamics - Mar 24
APS Minneapolis, symposium on Sculpting long-range entangled states with measurement and adaptive circuits - March 24
University of Minnesota - Feb 24
University of California, Berkeley - Jan 24
Stanford University - Dec 23
Cornell University - Oct 23
California Institute of Technology - Oct 23
Massachusetts Institute of Technology - July 23
University of Erlangen-Nuremberg - June 23
Simons Institute for the Theory of Computing, workshop on ‘Provable NISQ Quantum Advantage’ - June 23
University of Geneva - May 23
Institut Pascal, workshop on many-body quantum chaos - Apr 23
University of Oxford, Quantum Interactive Dynamics - Mar 23
University of California, Berkeley, Geoflow - Mar 23
University of California, Los Angeles - Mar 23
McGill University - Feb 23
University of Montreal - Feb 23
University of California, Santa Cruz - Feb 23
University of Geneva - Jan 23
Weizmann Institute, workshop on quantum many-body systems - Dec 22
New York, conference on frontiers of quantum condensed matter physics - Nov 22
KITP, workshop on quantum many-body dynamics and NISQ systems - Sep 22
University of Bonn - Jun 22
University of Cologne - Jun 22
PKS Dresden, workshop on Quantum chaos and holography - Jun 22
Emergent Phenomena in Quantum Systems, Postdoc Symposium - May 22
APS Chicago, symposium on many-body localisation - Mar 22