Logarithmic current fluctuations in non-equilibrium quantum spin chains

Understand

We study zero-temperature quantum spin chains which are characterized by a non-vanishing current.

• For the XX model starting from the initial state |...
• + + + - - - ...> we derive an exact expression for the variance of the total spin current.
• We show that asymptotically the variance exhibits an anomalously slow logarithmic growth; we also extract the sub-leading constant term.