Generation and Coherent Control of Pulsed Quantum Frequency Combs

Summary

A protocol is presented for the practical generation and coherent manipulation of high-dimensional frequency-bin entangled photon states using integrated micro-cavities and standard telecommunications components, respectively.

Abstract

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional states on-chip in a practical way have remained elusive due to the increasing complexity of the quantum circuitry needed to prepare and process such states. Here, we outline how high-dimensional, frequency-bin entangled, two-photon states can be generated at a stable, high generation rate by using a nested-cavity, actively mode-locked excitation of a nonlinear micro-cavity. This technique is used to produce pulsed quantum frequency combs. Moreover, we present how the quantum states can be coherently manipulated using standard telecommunications components such as programmable filters and electro-optic modulators. In particular, we show in detail how to accomplish state characterization measurements such as density matrix reconstruction, coincidence detection, and single photon spectrum determination. The presented methods form an accessible, reconfigurable, and scalable foundation for complex high-dimensional state preparation and manipulation protocols in the frequency domain.

Introduction

The control of quantum phenomena opens the possibility for new applications in fields as diverse as secure quantum communications¹, powerful quantum information processing², and quantum sensing³. While a variety of physical platforms are actively being researched for the realizations of quantum technologies⁴, optical quantum states are important candidates as they can exhibit long coherence times and stability from external noise, excellent transmission properties, as well as compatibility with existing telecommunications and silicon chip (CMOS) technologies.

Protocol

1. Generation of the High-dimensional Frequency-bin Entangled States via Pulsed Excitation

1. Following the scheme outlined in Figure 2 (Generation stage), connect each component using polarization-maintaining optical fibers (for improved environmental stability).
2. Connect a power supply to the electro-optic amplitude modulator and apply a DC voltage offset, tuning the offset value until the optical power transmitted through it is approximately halved (measured using an optical power meter), e.g., such that a peak transmission value of 2 mW is halved to 1 mW.
3. Measure the approximate external cavity len....

Results

The outlined scheme for the generation and control of high-dimensional frequency-bin states (based on the excitation of nonlinear micro-cavities, Figure 1) is shown in Figure 2. This setup uses standard telecommunications components and is highly flexible in the photon production rate and the processing operations applied. Figure 3 shows the characterization of the generation scheme through the coinc.......

Discussion

The optical frequency-domain, via QFCs, is advantageous in quantum applications for a host of reasons. Operations are global, acting on all states simultaneously, which results in a design that does not scale in size or complexity as the state dimensionality increases. This is enhanced as the components can be reconfigured on-the-fly without changing the setup and are capable of being integrated on-chip by exploiting existing and/or developing semiconductor and telecommunications infrastructures. The generation technique.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Superconducting Nanowire Single-Photon Detector System	Quantum Opus	Opus One
Electro-optic phase modulator	EO-Space	Low loss model
Programmable filter	Finisar	WaveShaper 4000s
Timing electronics	PicoQuant	HydraHarp 400
Micro-ring resonator			200 GHz FSR micro-ring resonator made from high refractive index glass. See Ref. 24 for platform details.
Erbium-doped fiber amplifier	Keopsys	PEFA-SP-C-PM-27-B202-FA-FA
Electro-optic amplitude modulator	Oclaro	SD40
RF tone source	Rohde & Schwarz	SMP 04
RF tone amplifier	RF-Lambda	RFLUPA27G34GA
Function generator	Tetronix	AFG 3251
Isolator	General Photonics	NISO-S-15-SS-FC/APF
Oscilloscope	Tetronix	TDS5052B
Photodiode	Finisar	XPDV 50 GHz
DWDM	OptiWorks	DWFUQUMD08BN
Power supply	Madell	CA18303D