PHYC 500.001 Adv Sem: “Many-body quantum chaos”

Course coordinator: Pablo M. Poggi (ppoggi@unm.edu)

Course duration: June 2nd  to August 4th 2021 (there will be ten sessions in total). All sessions will be held online via Zoom.

 

Format: This course is a survey of topics broadly related to chaos in quantum systems, with emphasis in its manifestations in many-body quantum systems.  The course is designed to be a ‘self-study’ program. In the first two sessions, we will introduce some basic aspects of quantum chaos and give an overview of the topics that will be treated later on. Reading material will be assigned every week, including lecture notes and research articles. In the remaining sessions, course participants will present sections from the reading material and facilitate group discussions. Participants are encouraged to also propose other topics of their interest.

 

Prerequisites: This course assumes familiarity with quantum mechanics at the level of Physics 521-522.

 

Assignments: All participants are required to read the materials assigned for each session and

participate in group discussions. Participants should be willing to present assigned material in later

sessions.

 

 

Syllabus and program: Sessions 1 and 2 will be given by course coordinator. Sessions 3 through 10 will be based presentations given by course participants.

 

Sessions 1 and 2 (June 2nd and 9th): Introduction and general aspects of quantum chaos

·       Notions from classical mechanics: Chaos and integrability, mixing, ergodicity

·       Aspects of quantum chaos in systems with few degrees of freedom 

o   Correlation in energy spectra. Level spacing statistics.

o   Eigenstate structure and relation to random vectors

o   Dynamics: Loschmidt echo and spectral form factors

·       Chaos in many-body quantum systems – overview of the course

References: [Haake] [Wimberger] [Gubin2012]

 

Session 3 (June 16th): Random matrix theory and chaos.

Gaussian and circular random matrix ensembles. Random eigenvectors and Porter Thomas distribution. Random matrix ensembles for many-body systems.

Reference: [Haake]. See also: [QChaosSantos]

Session 4 (June 23rd): Integrability in quantum systems

Notions of integrability in quantum systems. Integrability in many-body systems. Interacting vs non interacting models. Free fermions, Bethe ansatz and Richardson-Gaudin models.

References: [Caux2011] – [VieiraCostello2017]

 

Session 5 (June 30th): Thermalization in closed quantum systems

Equilibration, thermalization, and connection to random matrix aspects of quantum chaos. Eigenstate thermalization hypothesis (ETH). Constrained equilibrium and generalized Gibbs ensembles.

Reference: [D’Alessio2016]. See also: [Borgonovi2016], [Rigol2008], [Kaufman2016], [QChaosNation]


Session 6 (July 7th): Scrambling and out-of-time-order correlators I

Information spreading and scrambling in many body systems. Operator spreading and operator entanglement.

References: [Hosur2016], [SwingleLecNotes]. See also [Swingle2016], [Zhuang2019], [Google2020]

 

Session 7 (July 14th): Scrambling and out-of-time-order correlators II

Semiclassical theory of OTOCs and connection to Lyapunov exponents. Scrambling vs relaxation. Out-of-time-ordered and time-ordered correlation functions.

References: [Zhuang2019], [Swingle2016], [Rozenbaum2017], [Roberts2017]


Session 8 (July 21st): Random unitary evolution and quantum complexity

Haar randomness. Unitary t-designs and frame potentials. Random quantum circuits.

Main reference: [Roberts2017]. See also [Harrow2009], [Brandao2012].

 

Session 9 (July 26th): Deviations from chaos and ETH: Many body localization and quantum many body scars.

References: [Nandkishore2015] [QChaosBorhdt] [QChaosBurnell]

 

Session 10 (July 28th): Solvable chaotic systems (dual unitary circuits)

References: [Claeys2021] [Bertini 2020] [QChaosKos] [Aravinda2021]

 

Other topics (didn’t make the cut!)

·         Quantum information scrambling in black holes [Hayden2007] [Maldacena2015] 

·         Solvable chaotic systems (dual unitary circuits)

·         Sachdev-Ye-Kitaev (SYK) model and quantum chaos

·         Deviations from ETH: many body localization / quantum many body scars 

·         Chaos in open quantum systems (random Liouvillians)

·         Ergodicity and dynamical typicality

·         Chaos and information (KS entropy)

·         Quantum echoes and irreversibility

·         Adiabatic gauge potentials and sensitivity of eigenstates to perturbations

 

 

References

[Aravinda2021] Aravinda et al, From dual-unitary to quantum Bernoulli circuits: Role of the entangling power in constructing a quantum ergodic hierarchy. Arxiv: 2021.04580 (link)

[Bertini 2020] Bertini and Piroli, Scrambling in random unitary circuits: exact results. Phys. Rev. B 2020 (link)

[Borgonovi2016] Borgonovi, Izrailev, Santos, Zelevinsky, Quantum chaos and thermalization in isolated systems of interacting particles. Phys. Rep. 2016 (link)

[Brandao2012] Hunter-Jones, Local Random Quantum Circuits are Approximate Polynomial-Designs, Comm. Math. Phys. 2012 (link)

[Caux2011] Caux and Mossel, Remarks on the notion of quantum Integrability, J. Stat. Mech. 2011 (link)

[Claeys2021] Claeys and Lamacraft, Ergodic and Nonergodic Dual-Unitary Quantum Circuits with Arbitrary Local Hilbert Space Dimension, Phys. Rev. Lett. 2021 (link) 

[Cotler2017] Cotler, Hunter-Hones, Liu and Yoshida, Chaos, complexity, and random matrices, HEP 2017 (link)

[D’Alessio2016] D’Alessio, Kafri, Polkovnikov and Rigol. From quantum chaos and eigenstate thermalization to statistical mechanics and thermodynamics. Adv. Phys. 2016 (link)

[Google2020] Google team and others, Information Scrambling in Computationally Complex Quantum Circuits, arxiv 2021 (link)

[Gubin2012] Gubin and Santos, Quantum chaos: an introduction via chains of interacting spins ˝. Am. J. Phys. 2012 (link)

[Haake] F. Haake, Quantum Signatures of Chaos. Springer, Boston MA.

[Harrow2009] Harrow and Low, Random Quantum Circuits are Approximate 2-designs, Comm. Math. Phys. 2009 (link).

[Hayden2007] Hayden and Preskill, Black Holes as Mirrors, JHEP 2007 (link)

[Hosur2016] Hosur, Qi, Roberts and Yoshida, Chaos in quantum channels, JHEP 2016 (link)

[Kaufman2016] Kaufman et al, Quantum thermalization through entanglement in an isolated many-body system. Science 2016 (link)

[Maldacena2015] Maldacena, Shenker, Stanford, A bound on chaos, arxiv 2015 (link)

[Nandkishore2015] Nandkishore and Huse, Many-body localization and thermalization in quantum statistical mechanics. Annu. Rev. Condens. Matter Phys. 2015 (link)

[PolkovnikovLecNotes] A. Polkovnikov, Lecture notes on Quantum Ergodicity. http://physics.bu.edu/~asp28/teaching/PY_747.pdf 

[QChaosBohrdt] A. Bohrdt, Probing dynamics in quantum simulators, https://www.youtube.com/watch?v=yyZOi1BVPZI

[QChaosBurnell] F. Burnell, Exact models for many-body quantum scars, https://www.youtube.com/watch?v=IBpMcRd4T54

[QChaosKos] P. Kos, Solvable chaotic many-body quantum systems, https://www.youtube.com/watch?v=jL12q5F8XMw

[QChaosNation] C. Nation, Thermalization dynamics and the emergence of Brownian motion in chaotic quantum systems: https://www.youtube.com/watch?v=Rr_1oLfS8nw 

[QChaosSantos] L. Santos, Indicators of many-body quantum chaos: https://www.youtube.com/watch?v=h1-xFUJ_T_s&t=2950s

[Rigol2008] Rigol, Dunjko and Olshanii, Thermalization and its mechanism for generic isolated quantum systems. Nature 2008 (link)

[Roberts2017] Roberts and Yoshida, Chaos and complexity by design. JHEP 2017 (link)

[Rozenbaum2017] Rozenbaum, Ganeshan and Galitsky, Lyapunov Exponent and Out-of-Time-Ordered Correlator’s Growth Rate in a Chaotic System, PRL 2017 (link)

[Swingle2016] Swingle, Bentsen, Schleier-Smith and Hayden, Measuring the scrambling of quantum information, PRA 2016 (link)

[SwingleLecNotes] B. Swingle. Lecture notes on Quantum information scrambling (link)

[VieiraCostelloCourse] P. Vieira and K. Costello. Introduction to quantum integrable systems (link)

[Wimberger] S. Wimberger, Nonlinear dynamics and quantum chaos. Springer.

[Zhuang2019] Zhuang, Schuster, Yoshida and Yao, Scrambling and complexity in phase space. Phys. Rev. A 2019 (link)