Sorting photon wave packets using temporal-mode interferometry based on multiple-stage quantum frequency conversion

TL;DR

This paper advances the manipulation of optical temporal modes using multi-stage quantum frequency conversion, enabling near-perfect sorting of arbitrary orthogonal temporal modes with significant implications for quantum information processing.

Contribution

It introduces an extended multi-stage temporal-mode interferometry method that achieves near-unity selectivity for orthogonal temporal modes, surpassing previous limitations.

Findings

Achieves asymptotic convergence of mode selectivity to unity

Extends the method to multiple stages for improved performance

Provides analysis of pump-chirp compensation in four-wave mixing

Abstract

All classical and quantum technologies that encode in and retrieve information from optical fields rely on the ability to selectively manipulate orthogonal field modes of light. Such manipulation can be achieved with high selectivity for polarization modes and transverse-spatial modes. For the time-frequency degree of freedom, this could efficiently be achieved for a limited choice of approximately orthogonal modes, i.e. non-overlapping bins in time or frequency. We recently proposed a method that surmounts the selectivity barrier for sorting arbitrary orthogonal temporal modes [Opt. Lett. {\bf 39}, 2924 (2014)] using cascaded interferometric quantum frequency conversion in nonlinear optical media. We call this method temporal-mode interferometry, as it has a close resemblance to the well-known separated-fields atomic interferometry method introduced by Ramsey. The method has important implications for quantum memories, quantum dense coding, quantum teleportation, and quantum key distribution. Here we explore the inner workings of the method in detail, and extend it to multiple stages with a concurrent asymptotic convergence of temporal-mode selectivity to unity. We also complete our analysis of pump-chirp compensation to counter pump-induced nonlinear phase-modulation in four-wave mixing implementations.