Erecting time telescope for photonic quantum networks

TL;DR

This paper introduces a two-time-lens system called a time telescope that creates a chirpless temporal image, improving quantum network compatibility by minimizing residual temporal chirp.

Contribution

It develops a comprehensive theory for time telescopes, establishing conditions for loss minimization and practical construction methods.

Findings

Time telescope achieves chirpless temporal imaging.

Theoretical conditions for loss minimization are derived.

Applications include indistinguishable photon generation from quantum sources.

Abstract

A time lens allows one to stretch or compress optical waveforms in time, similar to the conventional lens in space. However, a single-time-lens imaging system always imparts a residual temporal chirp on the image, which may be detrimental for quantum networks, where the temporal image interacts with other fields. We show that a two-time-lens imaging system satisfying the telescopic condition, a time telescope, is necessary and sufficient for creating a chirpless image. We develop a general theory of a time telescope, find the conditions for loss minimization, and show how an erecting time telescope creating a real image of a temporal object can be constructed. We consider several applications of such a telescope to making indistinguishable the photons generated by spontaneous parametric downconversion or single emitters such as quantum dots.