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SUMMARY:How fast is Quantum?  Exploring the speed limits of quantum inform
 ation spread - Dr Vijay Ganesh Sadhasivam\, University of Cambridge
DTSTART:20260506T133000Z
DTEND:20260506T143000Z
UID:TALK243085@talks.cam.ac.uk
CONTACT:Lisa Masters
DESCRIPTION:In the last decade\, there has been an active interest in unde
 rstanding and quantifying the irreversible spread or ‘scrambling’ of q
 uantum information\, particularly through the dynamics of operators corres
 ponding to quantum observables. Research in these directions has led to th
 eoretical bounds on the speed of this spreading in quantum systems\, espec
 ially at finite temperature [1\,2]. This bound is known to be saturated by
  quantum models of black holes and interacting fermions\, and is satisfied
  by a wide range of quantum systems [3\,4]\, but the microscopic origin of
  this bound has remained largely elusive. Our work establishes the physica
 l origin of the bound [5]\, and grounds it in the theory of activated proc
 esses like chemical reactions [6] and the structure of the operator matrix
  elements [7]. In this talk\, I will present an overview of the mechanisms
  that limit the speed of quantum information transport. \n\n1. Maldacena\,
  J.\, Shenker\, S. H.\, & Stanford\, D. (2016). A bound on chaos. Journal 
 of High Energy Physics\, 2016(8)\, 106.\n2. Parker\, D. E.\, Cao\, X.\, Av
 doshkin\, A.\, Scaffidi\, T.\, & Altman\, E. (2019). A universal operator 
 growth hypothesis. Physical Review X\, 9(4)\, 041017.\n3. Swingle\, B. (20
 18). Unscrambling the physics of out-of-time-order correlators. Nature Phy
 sics\, 14(10)\, 988-990.\n4. Nandy\, P.\, Matsoukas-Roubeas\, A. S.\, Mart
 ínez-Azcona\, P.\, Dymarsky\, A.\, & del Campo\, A. (2025). Quantum dynam
 ics in Krylov space: Methods and applications. Physics Reports\, 1125\, 1-
 82.\n5. Sadhasivam\, V. G.\, Meuser\, L.\, Reichman\, D. R.\, & Althorpe\,
  S. C. (2023). Instantons and the quantum bound to chaos. Proceedings of t
 he National Academy of Sciences\, 120(49)\, e2312378120.\n6. Sadhasivam\, 
 V. G.\, Hunt\, A. C.\, Meuser\, L.\, Litman\, Y.\, & Althorpe\, S. C. (202
 4). Thermal quenching of classical and semiclassical scrambling. Physical 
 Review E\, 110(1)\, L012204.\n7. Sadhasivam\, V. G.\, Rost\, J. M.\, & Alt
 horpe\, S. C. (2025). On the origin of exponential operator growth in Hilb
 ert space. arXiv preprint arXiv:2511.02800.
LOCATION:Unilever Lecture Theatre\, Yusuf Hamied Department of Chemistry
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