Date: Friday, October 29, 2021 | 10:00 (GMT+1) (Virtual)
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Prof. Marcello Dalmonte | International Centre for Theoretical Physics (ICTP), Trieste, Italy.
TITLE:
Symmetry-resolved dynamical purification in noisy intermediate-scale quantum devices.
ABSTRACT:
When a quantum system initialized in a product state is subjected to either coherent or incoherent dynamics, the entropy of any of its connected partitions generically increases as a function of time, signalling the inevitable spreading of (quantum) information throughout the system. Here, we show that, in the presence of continuous symmetries and under ubiquitous experimental conditions, symmetry-resolved information spreading is inhibited due to the competition of coherent and incoherent dynamics: in given quantum number sectors, entropy decreases as a function of time, signalling dynamical purification. Such dynamical purification bridges between two distinct short and intermediate time regimes, characterized by a log-volume and log-area entropy law, respectively.
We then develop a protocol to measure symmetry-resolved entropies and negativities in synthetic quantum systems based on the random unitary toolbox, and demonstrate the generality of dynamical purification by showing that it has already been realized in trapped ion experiments [Brydges et al, Science 364, 260 (2019)]. This demonstrates how symmetry plays a key role as a 'lens' to characterize many-body dynamics in open quantum systems, that is of particular relevance to experimentally ubiquitous noisy-intermediate scale quantum devices.
If time allows, I will also discuss a more quantum-information motivated approach to symmetry-resolved entanglement, introducing a set of inequalities that rigorously prove violations of the positive-partial transpose condition, and by showing how those allow to certify many-body entanglement in q quantum quench on the longest timescales to date.
