Gabriele De Chiara
Quantum correlations in spin chains.
The relationship between the entanglement spectrum of the ground state of a one dimensional spin chain and the order parameter characterising its phase is discussed. The Schmidt gap, the difference of the two largest eigenvalues of the reduced density matrix of half the chain, scales with universal critical exponents [1,2] for the ground state and for the dynamical evolution after a quench [3]. Moreover, quantum correlations as measured by quantum discord are another quantum information inspired quantity that can reveal critical properties of quantum systems and are not limited to zero temperatures [4].
Finally, I will show that the full distribution of collective observables in quantum spin chains becomes highly non-Gaussian near a quantum phase transition and discuss its scaling. A scheme to measure the distribution using quantum polarisation spectroscopy in optical lattices will be explained [5].
References:
[1] G. De Chiara, L. Lepori, M. Lewenstein, A. Sanpera, Phys. Rev. Lett. 109, 237208 (2012).
[2] L. Lepori, G. De Chiara, A. Sanpera, Phys. Rev. B 87 235107 (2013).
[3] G. Torlai, L. Tagliacozzo, G. De Chiara, J. Stat. Mech. (2014) P06001.
[4] M. J. M. Power, S. Campbell, M. Moreno-Cardoner, G. De Chiara, Phys. Rev. B 91, 214411 (2015).
[5] M. Moreno-Cardoner, J. F. Sherson, G. De Chiara, arXiv:1510.05959