An hybrid III-V / Silicon source of photon pairs

Combining the generation and manipulation of quantum states of light on a single chip at room temperature is one of the crucial requirements for the development of scalable and practical quantum information technologies. This work proposes a hybrid solution that integrates two highly complementary semiconductor material platforms on a miniaturized device. This approach leverages the strengths of each material while mitigating their respective limitations, resulting in enhanced functionality.

Specifically, the researchers have utilized the optical properties of AlGaAs, a direct bandgap semiconductor, to produce pairs of entangled photons in the telecom band under excitation by an external laser. Entanglement, a nonclassical correlation at the core of quantum mechanics, is a critical resource for quantum information applications. The generated entangled photons are then transferred to a silicon-on-insulator (SOI) photonic circuit, which is adhesively bonded to the AlGaAs source. This transfer process is designed to transmit only the relevant signal while filtering out the external pump laser. Silicon, being the most mature material platform due to its extensive use in the industry, enables the implementation of complex optical circuits for custom manipulation of light. Therefore, the device produces two-photon quantum states using an active and efficient material such as AlGaAs and transfers them to an SOI circuit while preserving their essential properties for practical applications, i.e. high brightness, large bandwidth, and entanglement quality.

This device opens the way to the implementation of fully on-chip quantum information protocols: while the required manipulation elements are ready to be integrated on the SOI side, the direct bandgap of AlGaAs can be harnessed to integrate the laser pump within the same device, thus enabling compact and standalone quantum photonic circuits for out-of-the-lab implementations of quantum information protocols.

Reference :

Hybrid III-V/Silicon quantum photonic device generating broadband entangled photon pairs

J. Schuhmann, L. Lazzari, A. Lemaître, I. Sagnes, G. Beaudoin, M. Amanti, F. Boeuf, F. Raineri, F. Baboux, S. Ducci

PRX Quantum 5, 040321 (2024)