Shaping the Phase of a Single Photon

TL;DR

This paper demonstrates the ability to arbitrarily control the phase of a single photon without altering its amplitude, enabling complete wave packet manipulation for advanced quantum communication applications.

Contribution

It introduces a method for deterministic phase shaping of single photons, expanding control over quantum states beyond amplitude, frequency, and polarization.

Findings

Phase control verified via two-photon interference

Phase modulation does not affect amplitude profile

Enables complete control of single-photon wave packets

Abstract

While the phase of a coherent light field can be precisely known, the phase of the individual photons that create this field, considered individually, cannot. Phase changes within single-photon wave packets, however, have observable effects. In fact, actively controlling the phase of individual photons has been identified as a powerful resource for quantum communication protocols. Here we demonstrate the arbitrary phase control of a single photon. The phase modulation is applied without affecting the photon's amplitude profile and is verified via a two-photon quantum interference measurement, which can result in the fermionic spatial behaviour of photon pairs. Combined with previously demonstrated control of a single photon's amplitude, frequency, and polarisation, the fully deterministic phase shaping presented here allows for the complete control of single-photon wave packets.