Weak-measurement-induced asymmetric dephasing: manifestation of intrinsic measurement chirality

TL;DR

This paper investigates how weak measurements induce asymmetric dephasing due to intrinsic chirality, revealing topological transitions and potential coherence enhancement in quantum systems.

Contribution

It introduces the concept of measurement-induced dephasing asymmetry linked to intrinsic chirality and identifies topological transitions in measurement protocols.

Findings

Dephasing can be asymmetric under path reversal due to measurement chirality.

Dephasing diverges at specific parameters indicating topological phase transitions.

Partial suppression of dephasing (coherency enhancement) can occur through path reversal.

Abstract

Geometrical dephasing is distinct from dynamical dephasing in that it depends on the trajectory traversed, hence it reverses its sign upon flipping the direction in which the path is traced. Here we study sequences of generalized (weak) measurements that steer a system in a closed trajectory. The readout process is marked by fluctuations, giving rise to dephasing. Rather than classifying the latter as "dynamical" and "geometrical", we identify a contribution which is invariant under reversing the sequence ordering and, in analogy with geometrical dephasing, one which flips its sign upon the reversal of the winding direction, possibly resulting in partial suppression of dephasing (i.e., "coherency enhancement"). This dephasing asymmetry (under winding reversal) is a manifestation of intrinsic chirality, which weak measurements can (and generically do) possess. Furthermore, the dephasing diverges at certain protocol parameters, marking topological transitions in the measurement-induced phase factor.