18:00  20:00 
Registration at guest house 4, library 
19:00  21:00 
Welcome reception and dinner at the MPIPKS 
20:00  21:30 
Informal discussions 
Chair morning session: Adolfo del Campo 

09:30  10:00 
Alvaro Alhambra
(Perimeter Institute for Theoretical Physics)
Dynamics of twopoint correlation functions in quantum manybody systems We give rigorous analytical results about the behavior of twopoint correlation functions in quantum many body systems undergoing unitary dynamics (also known as dynamical response functions or Green’s functions). These appear in the characterization of wide range of statistical and nonequilibrium phenomena, including quantum transport, fluctuationdissipation theorems, linear response theory or scattering experiments. First, using recent results from large deviation theory, we are able to show that in a large class of models the correlation functions factorize at late times, proving that dissipation emerges out of the unitary dynamics of the system. We also show that the fluctuations around this latetime value are bounded by the “effective dimension”, which generally decays exponentially with system size. This result connects the behavior of correlation functions to the physics of equilibration of quenched systems. Moreover, for autocorrelation functions such as (including the symmetric and antisymmetric versions) we provide an upper bound on the timescale at which they reach the “dissipated” late time value. Remarkably, this turns out to be related to local expectation values only, and it doesn’t increase with system size. We give numerical examples that illustrate how this upper bound is in fact a good estimate, and we argue this timescale can be understood in terms of an emergent fluctuationdissipation theorem. Our study extends to larger classes of two point functions. In particular, we also show that the Kubo correlation function that controls the linear response theory evolves under a similar timescale. 
10:00  10:30 
Coffee break 
10:30  11:00 
Uwe R. Fischer
(Seoul National University)
Autonomous quantum error correction by strong engineered dissipation and the KnillLaflamme condition Autonomous quantum error correction utilizes the engineered coupling of a quantum system to a dissipative ancilla to protect quantum logical states from decoherence. We show that the KnillLaflamme condition, stating that the environmental error operators should act trivially on a subspace, which then becomes the code subspace, is sufficient for logical qudits to be protected against Markovian noise. It is proven that the error caused by the total Lindbladian evolution in the code subspace can be suppressed up to very long times in the limit of large engineered dissipation, by explicitly deriving how the error scales with both time and engineered dissipation strength. To demonstrate the potential of our approach for applications, we implement our general theory with binomial codes, a class of bosonic errorcorrecting codes, and outline how they can be implemented in a fully autonomous manner to protect against photon loss in a microwave cavity. https://journals.aps.org/pra/abstract/10.1103/PhysRevA.98.012317 
11:00  11:30 
Brendon Lovett
(University of St. Andrews)
Efficient nonMarkovian quantum dynamics using timeevolving matrix product operators In order to model realistic quantum devices that are out of equilibrium, it is necessary to simulate quantum systems strongly coupled to their environment. To date, most understanding of open quantum systems has been restricted either to weak systembath couplings, or to special cases where specific numerical techniques become effective. Here we present a general and yet exact numerical approach that efficiently describes the time evolution of a quantum system coupled to a nonMarkovian environment [1]. The method combines path integral techniques [2] with tensor networks [3], and at its core is a timeevolving matrix product operator (TEMPO) description of quantum dynamics. We demonstrate the power and flexibility of TEMPO by numerically identifying the localisation transition of the Ohmic spinboson model [4], and considering a model with widely separated environmental timescales arising for a pair of spins embedded in a common environment. In the latter model, we are able to directly calculate the time evolution of the bath displacement close to the two quantum dots, and show how these influence the dot dynamics. We will finish by discussing some new predictions on the spectrum and dynamics of a quantum dot, that is driven strongly out of equilibrium. We observe the breakdown of polaron physics at strong driving. References: [1] A. Strathearn, P. Kirton, D. Kilda, J. Keeling, and B. W. Lovett, Efficient nonMarkovian quantum dynamics using timeevolving matrix product operators, arXiv:1711.09641 (2017) [2] N. Makri and D. E. Makarov Tensor propagator for iterative quantum time evolution of reduced density matrices J. Chem. Phys. 102, 4600 (1995) [3] R. Orús, A practical introduction to tensor networks, A practical introduction to tensor networks, Ann. Phys. 349 117 (2014) [4] A. J. Leggett et al. Dynamics of the dissipative twostate system, Rev. Mod. Phys. 59, 1 (1987) 
11:30  12:00 
Ken Funo
(RIKEN Cluster for Pioneering Research)
Speed limit for open quantum systems The quantum speed limit (QSL) inequality gives a fundamental lower bound on the operation time for the quantum control. Since it is related to the timeenergy uncertainty relation, the QSL has gathered significant interest among researchers in different fields. It is also relevant to applied physics, where QSL has been studied in various fields such as quantum computation, quantum metrology, quantum optimal control, and quantum thermodynamics. In actual experiments, the effect of the environment cannot be neglected, and extending the QSL to open quantum systems is needed. However, previous studies in formulating the QSLs remain as a formal mathematical expression. From their results, it is difficult to extract physical mechanism determining the speed in quantum dynamics. In the presentation, we discuss the QSL for open quantum systems described by the Lindblad master equation and formulate the QSL by using physical quantities such as the energy fluctuation and the entropy production [1]. These wellestablished quantities allow us to obtain intuition about how one can speed up quantum operations in open systems. In addition, the obtained QSL unifies the previously obtained results for isolated quantum and classical stochastic [2] systems. We further identify a quantity characterizing the speed of the state transformation which has not been reported in previous literatures. In the thermodynamically quasiadiabatic regime, we show a nontrivial connection between this new quantity and the energy fluctuation of the counterdiabatic Hamiltonian used in shortcuts to adiabaticity. It may suggest further connection between the finitetime quantum control theory and QSLs. [1] K. Funo, N. Shiraishi, and K. Saito "Speed limit for open quantum systems" New Journal of Physics 21, 013006 (2019). [2] N. Shiraishi, K. Funo, and K. Saito "Speed Limit for Classical Stochastic Processes" Physical Review Letters 121, 070601 (2018). 
12:00  13:00 
Lunch break 
13:00  13:15 
Closing & departure 
Chair discussion session: Alvaro Alhambra 

13:15  16:00 
Discussions 