Considerations regarding one-photon phase control

TL;DR

This paper establishes a theoretical upper bound for one-photon phase control in quantum systems, revealing conditions under which phase control can be maintained or lost, and explaining experimental deviations through multiphoton effects.

Contribution

It derives a strict upper bound for phase control based on physical timescales, clarifying when phase control is theoretically possible or violated.

Findings

The bound interpolates between control over time-varying and steady-state quantities.

Experimental violations of the bound are explained by multiphoton effects.

The analysis highlights physical conditions affecting phase control limitations.

Abstract

The dynamics of a system interacting with an ultrashort pulse is known to depend on the phase content of said pulse. For linear absorption, phase control is possible over time-varying quantities, such as the population of metastable states, but not over time-independent quantities, such as the population of steady states. We derive here a strict upper bound for phase control that interpolates between these two cases --- the bound quantifies the approach to the steady state and resulting loss of one-photon phase control based on physical timescales. Significantly, this bound is violated by a number of numerical and experimental investigations. A careful analysis of the physical conditions underlying this result exposes multiphoton effects as a mechanism for these experiments.