A key challenge in today’s quantum science is the realization of large-scale complex non-classical systems to enable e.g. ultra-secure communications, quantum-enhanced measurements, and computations faster than classical approaches. Optical frequency combs represent a powerful approach towards this, since they provide a very high number of temporal and frequency modes which can result in large-scale quantum systems. Here, we discuss the recent progress on the realization of integrated quantum frequency combs and reveal how their use in combination with on-chip and fiber-optic telecommunications components can enable quantum state control with new functionalities, yielding unprecedented capability.
Optical frequency combs are the enabling technology of a myriad of areas of science and engineering, where the line frequency spacing plays a fundamental role in their areas of application. Here, we review recent research work on the proposal and experimental demonstration of a set of signal processing techniques based on linear phase-only operations, inspired by the theory of the Talbot effect. These are aimed at re-distributing the energy of periodic spectral waveforms, such as frequency combs, achieving an arbitrary control of their line spacing. The energy-preserving nature of such techniques provides them with the capability of mitigating the noise of the signals of interest in a deterministic way, even allowing for the detection and measurement of signals entirely buried under the noise floor.
This work shows the possibility of using chirped pulse amplification concepts in order to increase the signal-to-noise ratio (SNR) of phase sensitive optical time domain reflectometry (ΦOTDR) sensors. This method allows to increase the SNR of a ΦOTDR sensor without sacrificing spatial resolution. Here, we report a ΦOTDR sensor with a spatial resolution of 3 mm (limited only by the available detection equipment) and an SNR increase of 20 dB over the traditional architecture. To our knowledge, this is the highest-resolution ΦOTDR sensor reported to date.