Isotropic Transverse XY Chain with Energy- and Magnetization Currents

TL;DR

This paper studies how magnetization and energy currents affect ground-state correlations in an isotropic transverse XY chain, revealing oscillations, amplitude changes, and symmetry enhancements in correlation decay.

Contribution

It provides new insights into the effects of magnetization and energy currents on correlation decay and ground-state symmetry in the XY chain.

Findings

Magnetization current introduces oscillations and increases correlation decay amplitude.

Energy current generally accelerates correlation decay, but a special line exists with correlations similar to zero-current states.

Ground-state symmetry is enhanced at a specific current line with zero transverse magnetization.

Abstract

The ground-state correlations are investigated for an isotropic transverse XY chain which is constrained to carry either a current of magnetization J_M or a current of energy J_E. We find that the effect of nonzero J_M on the large-distance decay of correlations is twofold: i) oscillations are introduced and ii) the amplitude of the power law decay increases with increasing current. The effect of energy current is more complex. Generically, correlations in current carrying states are found to decay faster than in the J_E=0 states, contrary to expectations that correlations are increased by the presence of currents. However, increasing the current, one reaches a special line where the correlations become comparable to those of the J_E=0 states. On this line, the symmetry of the ground state is enhanced and the transverse magnetization vanishes. Further increase of the current destroys the extra symmetry but the transverse magnetization remains at the high-symmetry, zero value.