Zapraszamy w poniedziałek 28.10.2019 o godz. 12:15, sala 361 na seminarium.
Wykład pod tytułem: "Quantum Information Processing in Noisy Environments" poprowadzi Sreetama Das (Harish-Chandra Research Instutute).
I will discuss various quantum informatic aspects when a system is interacting with an environment and the effects of disorder on the system induced by the environment. We study the ground state of a Hubbard model, which in the limit of large onsite interactions, is governed by the t-J Hamiltonian. We see that, in presence of doping, the entanglement is immutable under perturbative or sudden changes of system parameters, a phenomenon termed as adiabatic freezing. Significantly, at low fixed electron densities, the multipartite entanglement remains frozen across all parameter space. We also consider a quantum random walk, where we introduce a disorder in the number of steps a particle can take after each coin toss. These number of steps are independent and randomly chosen from Poisson distribution. We find that the spread of the walker is significantly inhibited, whereby it resides in the near-origin region, with respect to the case when there is no disorder. The scaling exponent of the quenched-averaged dispersion of the walker is sub-ballistic but super-diffusive. We also show that the features are universal to a class of sub- and super-Poissonian distributed quenched randomized jumps. If time permits, I will also discuss our work which derives an entanglement-based bound on non-Markovian behaviour of dynamics of a quantum system and necessarily transient cooling in quantum refrigerators.
References: 1. Adiabatic freezing of entanglement with insertion of defects in one-dimensional Hubbard model, arXiv:1708.07005. 2. Inhibition of spreading in quantum random walks due to quenched Poisson-distributed disorder, arXiv:1806.04024. 3. Almost Markovian maps and entanglement-based bound on corresponding non-Markovianity, arXiv:1905.06198. 4. Necessarily transient quantum refrigerator, arXiv:1606.06985.