Quantum Many-Body Scars
Lead Research Organisation:
University of Leeds
Department Name: Physics and Astronomy
Abstract
In recent years, investigations of out-of-equilibrium phenomena in quantum many-particle
systems have become one of the most active research areas in physics. A recent state-of-theart
experiment at Harvard/MIT [1] has succeeded in assembling large chains of stronglyinteracting
Rydberg atoms, which allowed them to build an impressive 51-atom quantum
simulator. This experiment discovered a new physical phenomenon: when the simulator was
driven away from its equilibrium configuration, the experiment observed enigmatic quantum
oscillations that remained coherent for unusually long times. In our recent work [2] (which was
also featured in Press, see [3, 4]) we provided an explanation of this intriguing phenomenon
by introducing a new concept of quantum many-body scar.
The goal of this PhD project is to develop a deeper understanding of quantum many-body
scars as a new class of systems where ergodicity is weakly broken. One of the pressing
questions is what kind of systems support scars. Currently, it is believed that kinetic
constraints (such as strong nearest-neighbour interactions between the atoms) are essential
to the formation of scars, thus one of the goals of the project would be to investigate more
systematically other types of models with similar constraints. On the other hand, the project
will aim to answer a fundamental question: what is the meaning of a periodic orbit in a
quantum many-body system? Such orbits play a fundamental role in the theory of singleparticle
chaotic billiards, but their meaning for a quantum many-body system is currently an
open problem. Finally, the project will also investigate possible practical applications of
quantum scars. Since the scars effectively "shield" the system from thermal relaxation, this
might allow for new mechanisms of storing and manipulating quantum information.
[1] Probing many-body dynamics on a 51-atom quantum simulator, H. Bernien et al., Nature 551, 579-584
(2017).
[2] Quantum many-body scars, C. J. Turner, A. A. Michailidis, D. A. Abanin, M. Serbyn, and Z. Papic, Nature
Physics 14, 745 (2018).
[3] https://www.leeds.ac.uk/news/article/4231/insight_into_quantum_chaos_may_be_the_key_to_quantum_comp
uters
[4] https://ist.ac.at/nc/news-media/news/news-detail/article/explanation-for-puzzling-quantum-oscillations-hasbeen-
found/6/
systems have become one of the most active research areas in physics. A recent state-of-theart
experiment at Harvard/MIT [1] has succeeded in assembling large chains of stronglyinteracting
Rydberg atoms, which allowed them to build an impressive 51-atom quantum
simulator. This experiment discovered a new physical phenomenon: when the simulator was
driven away from its equilibrium configuration, the experiment observed enigmatic quantum
oscillations that remained coherent for unusually long times. In our recent work [2] (which was
also featured in Press, see [3, 4]) we provided an explanation of this intriguing phenomenon
by introducing a new concept of quantum many-body scar.
The goal of this PhD project is to develop a deeper understanding of quantum many-body
scars as a new class of systems where ergodicity is weakly broken. One of the pressing
questions is what kind of systems support scars. Currently, it is believed that kinetic
constraints (such as strong nearest-neighbour interactions between the atoms) are essential
to the formation of scars, thus one of the goals of the project would be to investigate more
systematically other types of models with similar constraints. On the other hand, the project
will aim to answer a fundamental question: what is the meaning of a periodic orbit in a
quantum many-body system? Such orbits play a fundamental role in the theory of singleparticle
chaotic billiards, but their meaning for a quantum many-body system is currently an
open problem. Finally, the project will also investigate possible practical applications of
quantum scars. Since the scars effectively "shield" the system from thermal relaxation, this
might allow for new mechanisms of storing and manipulating quantum information.
[1] Probing many-body dynamics on a 51-atom quantum simulator, H. Bernien et al., Nature 551, 579-584
(2017).
[2] Quantum many-body scars, C. J. Turner, A. A. Michailidis, D. A. Abanin, M. Serbyn, and Z. Papic, Nature
Physics 14, 745 (2018).
[3] https://www.leeds.ac.uk/news/article/4231/insight_into_quantum_chaos_may_be_the_key_to_quantum_comp
uters
[4] https://ist.ac.at/nc/news-media/news/news-detail/article/explanation-for-puzzling-quantum-oscillations-hasbeen-
found/6/
Organisations
- University of Leeds (Lead Research Organisation)
- Zhejiang University (Collaboration)
- Arizona State University (Collaboration)
- Ludwig Maximilian University of Munich (LMU Munich) (Collaboration)
- Heidelberg University (Collaboration)
- University of Belgrade (Collaboration)
- Trinity College Dublin (Collaboration)
- École Normale Supérieure, Paris (Collaboration)
- University of Science and Technology of China USTC (Collaboration)
Publications
Bull K
(2020)
Quantum scars as embeddings of weakly broken Lie algebra representations
in Physical Review B
Desaules J
(2022)
Hypergrid subgraphs and the origin of scarred quantum walks in many-body Hilbert space
in Physical Review B
Desaules JY
(2022)
Extensive Multipartite Entanglement from su(2) Quantum Many-Body Scars.
in Physical review letters
Desaules JY
(2021)
Proposal for Realizing Quantum Scars in the Tilted 1D Fermi-Hubbard Model.
in Physical review letters
Hudomal A
(2022)
Driving quantum many-body scars in the PXP model
in Physical Review B
Turner C
(2021)
Correspondence Principle for Many-Body Scars in Ultracold Rydberg Atoms
in Physical Review X
Zhang P
(2022)
Many-body Hilbert space scarring on a superconducting processor
in Nature Physics
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/R513258/1 | 01/10/2018 | 30/09/2023 | |||
| 2282779 | Studentship | EP/R513258/1 | 01/10/2019 | 31/03/2023 | Jean-Yves Desaules |
| Description | The main focus of this award was to study quantum many-body scarring (QMBS): a phenomenon that leads to the presence of coherent oscillations in an otherwise chaotic system. This was puzzling, and only few quantum systems were known to exhibit it. In particular, the only experimental realisation was in a chain of Rydberg atoms. The name "scarring" comes from the similarities of QMBS with single-particle quantum scarring, a similar phenomenon shown to happen in quantum billiards. If both single and many body scarring share coherent oscillations in a chaotic background, the link between the two was not well understood. Through the worked funded by the award, we have shown a stronger connection between them. We demonstrated that the construction of special states called "quasimodes" can also be done for QMBS. As these states were crucial in formally proving that single-particle scarring breaks an important property known as ergodicity, our construction paves the way to a similar proof for QMBS. After that, we have established the presence of QMBS in other models that are realisable experimentally. This includes realisation in both fermionic and bosonic cold-atoms, as well as superconducting qubits. International collaborations with scientists at Hefei National Laboratory (China), at the Physikalisches Institut in Heidelberg (Germany) and at Zhejiang University (china) have allowed us to test some of our proposals experimentally. In parallel, in collaboration with the Trinity University in Dublin and the ENS Paris, we established that in many quantum systems displaying QMBS, there exists states that have extensive quantum Fisher information. This means that these states are very sensitive to small changes, and can be used to get accurate measurements in quantum sensing. |
| Exploitation Route | By making quantum many-body scarring available on a wider range on experimental setups and showing that they are a useful resource in quantum metrology, we have opened the way for these states to be used in quantum sensing technologies. |
| Sectors | Digital/Communication/Information Technologies (including Software) |
| URL | https://www.newswise.com/articles/arizona-state-and-zhejiang-universities-reach-qubit-computing-breakthrough |
| Description | Multipartite entanglement |
| Organisation | Trinity College Dublin |
| Country | Ireland |
| Sector | Academic/University |
| PI Contribution | We provided theoretical knowledge of quantum many-body scars. We performed all the numerical simulations needed. |
| Collaborator Contribution | Our collaborators provided theoretical knowledge on multipartite entanglement and on the structure of eigenstates. |
| Impact | This collaboration lead to the publication of a scientific article in Physical Review Letters (https://doi.org/10.1103/PhysRevLett.129.020601). |
| Start Year | 2020 |
| Description | Multipartite entanglement |
| Organisation | École Normale Supérieure, Paris |
| Country | France |
| Sector | Academic/University |
| PI Contribution | We provided theoretical knowledge of quantum many-body scars. We performed all the numerical simulations needed. |
| Collaborator Contribution | Our collaborators provided theoretical knowledge on multipartite entanglement and on the structure of eigenstates. |
| Impact | This collaboration lead to the publication of a scientific article in Physical Review Letters (https://doi.org/10.1103/PhysRevLett.129.020601). |
| Start Year | 2020 |
| Description | Scarring in cold atom systems |
| Organisation | Heidelberg University |
| Country | Germany |
| Sector | Academic/University |
| PI Contribution | We are providing theoretical knowledge of quantum many-body scars and are performing large scale numerical simulations. |
| Collaborator Contribution | Our partners provide theoretical knowledge of cold-atom simulators and lattice gauge theories. They also perform the experiments on an actual Bose-Hubbard quantum simulator. |
| Impact | The collaboration led to the publication of a scientific article in the journal Physical review B (https://doi.org/10.1103/PhysRevB.106.104302). Several additional articles are currently under reviews by journals. |
| Start Year | 2021 |
| Description | Scarring in cold atom systems |
| Organisation | Ludwig Maximilian University of Munich (LMU Munich) |
| Country | Germany |
| Sector | Academic/University |
| PI Contribution | We are providing theoretical knowledge of quantum many-body scars and are performing large scale numerical simulations. |
| Collaborator Contribution | Our partners provide theoretical knowledge of cold-atom simulators and lattice gauge theories. They also perform the experiments on an actual Bose-Hubbard quantum simulator. |
| Impact | The collaboration led to the publication of a scientific article in the journal Physical review B (https://doi.org/10.1103/PhysRevB.106.104302). Several additional articles are currently under reviews by journals. |
| Start Year | 2021 |
| Description | Scarring in cold atom systems |
| Organisation | University of Belgrade |
| Country | Serbia |
| Sector | Academic/University |
| PI Contribution | We are providing theoretical knowledge of quantum many-body scars and are performing large scale numerical simulations. |
| Collaborator Contribution | Our partners provide theoretical knowledge of cold-atom simulators and lattice gauge theories. They also perform the experiments on an actual Bose-Hubbard quantum simulator. |
| Impact | The collaboration led to the publication of a scientific article in the journal Physical review B (https://doi.org/10.1103/PhysRevB.106.104302). Several additional articles are currently under reviews by journals. |
| Start Year | 2021 |
| Description | Scarring in cold atom systems |
| Organisation | University of Science and Technology of China USTC |
| Department | Hefei National Laboratory for Physical Sciences at the Microscale |
| Country | China |
| Sector | Charity/Non Profit |
| PI Contribution | We are providing theoretical knowledge of quantum many-body scars and are performing large scale numerical simulations. |
| Collaborator Contribution | Our partners provide theoretical knowledge of cold-atom simulators and lattice gauge theories. They also perform the experiments on an actual Bose-Hubbard quantum simulator. |
| Impact | The collaboration led to the publication of a scientific article in the journal Physical review B (https://doi.org/10.1103/PhysRevB.106.104302). Several additional articles are currently under reviews by journals. |
| Start Year | 2021 |
| Description | Superconducting quantum platform |
| Organisation | Arizona State University |
| Country | United States |
| Sector | Academic/University |
| PI Contribution | We are contributing to this collaboration with our theoretical knowledge of quantum many-body scars. We are also performing a large part of the numerical simulations needed. |
| Collaborator Contribution | Our collaborators perform some of the theoretical and numerical work. They also create the experimental samples and perform the necessary experiments and measurements on them. |
| Impact | The collaboration lead to the publication of a scientific article in the journal Nature Physics (https://doi.org/10.1038/s41567-022-01784-9). This also led to a few articles on more mainstream news websites (e.g. https://www.newswise.com/articles/arizona-state-and-zhejiang-universities-reach-qubit-computing-breakthrough). |
| Start Year | 2021 |
| Description | Superconducting quantum platform |
| Organisation | Zhejiang University |
| Country | China |
| Sector | Academic/University |
| PI Contribution | We are contributing to this collaboration with our theoretical knowledge of quantum many-body scars. We are also performing a large part of the numerical simulations needed. |
| Collaborator Contribution | Our collaborators perform some of the theoretical and numerical work. They also create the experimental samples and perform the necessary experiments and measurements on them. |
| Impact | The collaboration lead to the publication of a scientific article in the journal Nature Physics (https://doi.org/10.1038/s41567-022-01784-9). This also led to a few articles on more mainstream news websites (e.g. https://www.newswise.com/articles/arizona-state-and-zhejiang-universities-reach-qubit-computing-breakthrough). |
| Start Year | 2021 |
| Description | Collaboration with artist |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Postgraduate students |
| Results and Impact | I took part in the Leeds Creative Labs: PGR Edition. For this, I collaborated with a PhD student in poetry performance to produce works relating to both our fields of study. The theme we explored was randomness and chaos. We presented our results in front of an audience composed of other PhD students and more senior faculty members. |
| Year(s) Of Engagement Activity | 2022 |
| URL | https://medium.com/cultural-institute/inspired-by-bragg-meet-the-pgr-students-working-at-the-centre-... |
| Description | Quantum computing workshop |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Schools |
| Results and Impact | As part of the "Reach for Excellence" program of the University of Leeds (https://contextualoutreach.leeds.ac.uk/rfe/), I prepared and ran a 2 hour workshop to explain quantum computing to a group of about 20 students in Year 12 and Year 13. The workshop had a theoretical part in which they learnt about the fundamentals of quantum mechanics and a practical part in which they learnt to use the IBM quantum programming platform. Students reported a good level of satisfaction, giving an average score of 7.9/10 to the statement "I enjoyed the session and found it useful" and of 7.7/10 to "After today's session, I have a better understanding of quantum technology and its advantages" |
| Year(s) Of Engagement Activity | 2022 |
| URL | https://theory.leeds.ac.uk/outreach/qcho/ |