Polarization entangled photons from quantum dots embedded in nanowires

Area of Science:

• Quantum physics
• Materials science
• Nanotechnology

Background:

• Quantum entanglement is a key resource for quantum computing and communication.
• Developing efficient sources of entangled photons is crucial for advancing quantum technologies.
• Semiconductor quantum dots offer a promising platform for generating quantum entanglement.

Purpose of the Study:

• To demonstrate entanglement generation from a novel quantum dot-nanowire heterostructure.
• To characterize the efficiency and fidelity of the generated entangled photons.
• To explore the potential of this new structure for quantum information applications.

Main Methods:

• Fabrication of a single Indium Arsenide Phosphide (InAsP) quantum dot embedded within an Indium Phosphide (InP) nanowire.
• Site-controlled growth of the quantum dot-nanowire structures.
• Characterization of biexciton emission rates and photon collection efficiency using avalanche photodiodes and single-mode fiber.
• Measurement of polarization entanglement fidelity and concurrence.

Main Results:

• Achieved high biexciton counts (0.5 million per second) coupled into a single-mode fiber.
• Determined an extraction efficiency of 15(3) % after accounting for system losses.
• Measured a polarization entanglement fidelity of 0.76(2) and a concurrence of 0.57(6).

Conclusions:

• The novel InAsP quantum dot in InP nanowire structure is a viable and efficient source of quantum entanglement.
• The demonstrated high collection and extraction efficiencies are promising for practical quantum information processing.
• Site-controlled growth enables scalable fabrication of quantum entanglement sources.