# Temporal and spectral manipulations of correlated photons using a time-lens

## TL;DR

This paper demonstrates a time-lens technique to magnify and measure ultrafast temporal correlations in entangled photon pairs, enabling manipulation and analysis of spectral and temporal quantum states beyond detector limitations.

## Contribution

It introduces a novel application of a time-lens to measure and manipulate temporal and spectral correlations in multi-photon quantum states, surpassing current detector resolution limits.

## Key findings

- Successfully measured temporal correlations of entangled photons using a time-lens.
- Mapped temporal correlations to frequency correlations with the time-lens.
- Enabled manipulation of frequency-bin entangled photons.

## Abstract

A common challenge in quantum information processing with photons is the limited ability to manipulate and measure correlated states. An example is the inability to measure picosecond scale temporal correlations of a multi-photon state, given state-of-the-art detectors have a temporal resolution of about 100 ps. Here, we demonstrate temporal magnification of time-bin entangled two-photon states using a time-lens, and measure their temporal correlation function which is otherwise not accessible because of the limited temporal resolution of single photon detectors. Furthermore, we show that the time-lens maps temporal correlations of photons to frequency correlations and could be used to manipulate frequency-bin entangled photons. This demonstration opens a new avenue to manipulate and analyze spectral and temporal wavefunctions of many-photon states.