Quantum Information Processing in Noisy Environments

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).

Abstract:

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.