Quantum optical frequency up-conversion for polarisation entangled qubits: towards interconnected quantum information devices.

Florian Kaiser,Anthony Martin,Marc P De Micheli,Olivier Alibart,Sébastien Tanzilli,Djeylan Aktas,Panagiotis Vergyris

doi:10.1364/oe.27.025603

Abstract

Realising a global quantum network requires combining individual strengths of different quantum systems to perform universal tasks, notably using flying and stationary qubits. However, transferring coherently quantum information between different systems is challenging as they usually feature different properties, notably in terms of operation wavelength and wavepacket. To circumvent this problem for quantum photonics systems, we demonstrate a polarisation-preserving quantum frequency conversion device in which telecom wavelength photons are converted to the near infrared, at which a variety of quantum memories operate. Our device is essentially free of noise, which we demonstrate through near perfect single photon state transfer tomography and observation of high-fidelity entanglement after conversion. In addition, our guided-wave setup is robust, compact, and easily adaptable to other wavelengths. This approach therefore represents a major building block towards advantageously connecting quantum information systems based on light and matter.

Highlights

Quantum technologies have the potential to revolutionise the way information is processed and communicated [1, 2]
Photons are generally preferred for quantum communication purposes [10,11,12], and minimal loss in fibre networks is obtained at telecom wavelengths (λ ∼ 1.55 μm)
Quantum computation, storage, and metrology tasks are usually performed with matter based systems that interact with wavelengths ranging from the visible to the near infrared band (λ ∼ 600 − 900 nm) [13,14,15]

Summary

Introduction

Quantum technologies have the potential to revolutionise the way information is processed and communicated [1, 2]. We demonstrate a novel quantum interface in which single photons are converted via sum frequency generation (SFG) in nonlinear crystals from 1560 nm to 795 nm. Key features of our approach are a high conversion efficiency and the preservation of polarisation quantum states with high fidelity.

Results

Conclusion