Transcoherent states: Optical states for maximal generation of atomic coherence

TL;DR

This paper introduces special quantum states of light that can generate perfect atomic coherence without entanglement, outperforming traditional coherent states and enabling repeated high-probability atomic state preparation.

Contribution

It identifies quantum light states that produce ideal atomic superpositions without atom-field entanglement, extending the concept of coherent states for quantum control.

Findings

States can generate perfect atomic coherence with no residual entanglement.

These states approach number-squeezed $ frac{ au}{2}$ pulses at high intensities.

Repeated use as 'quantum catalysts' enables high-probability atomic state generation.

Abstract

Quantum technologies are built on the power of coherent superposition. Atomic coherence is typically generated from optical coherence, most often via Rabi oscillations. However, canonical coherent states of light create imperfect resources; a fully-quantized description of "$\tfrac{\pi}{2}$ pulses" shows that the atomic superpositions generated remain entangled with the light. We show that there are quantum states of light that generate coherent atomic states perfectly, with no residual atom-field entanglement. These states can be found for arbitrarily short times and approach slightly-number-squeezed $\tfrac{\pi}{2}$ pulses in the limit of large intensities; similar ideal states can be found for any $(2k+1)\tfrac{\pi}{2}$ pulses, requiring more number squeezing with increasing $k$. Moreover, these states can be repeatedly used as "quantum catalysts" to successfully generate coherent atomic states with high probability. From this perspective we have identified states that are "more coherent" than coherent states.