Photonic quantum information processing demands efficient quantum light sources combined with optical networks that process photons. Integrating these components onto a single chip would result to quantum photonic devices that enable quantum communication networks, photonic quantum computers, and photonic quantum simulators. Most of these applications depend on optical qubits that exhibit two-photon quantum interference on a beam splitter, which is the primary mechanism for achieving efficient photon-photon interactions.
Optical cavities greatly enhance the collection efficiency and spontaneous emission rate of quantum emitters. Emitters coupled to cavities serve as highly nonlinear devices operating at low-photon numbers and efficient interfaces between photons and solid state quantum memory.
Under the lead of Prof. Edo Waks from the University of Maryland, Je-Hyung Kim and colleagues proposed a method to investigate two-photon interference from the far-field emission of chip-integrated cavity-coupled emitters. Their work focused on demonstrating a method to integrate multiple solid-state emitters resonantly coupled to cavities on the same chip and showing that the emitters exhibit two-photon interference. Their work is now published in a peer-reviewed journal, Nano letters.
The researches coupled multiple InAs/InP quantum dots which served as efficient single photon sources to independent photonic crystal cavities fabricated in close proximity on the same chip. In a bid to match the cavity resonances and compensate for errors in the fabrication, they utilized a combination of nitrogen gas deposition and local thermal evaporation. Also, to compensate for the spectral mismatch of the quantum dot emitters, they fabricated thermally isolated photonic crystal devices integrated with optical heaters, which enabled them to tune individual dots without affecting nearby devices.
The researchers combined the two methods in order to match the resonant frequencies of independent quantum dots coupled to cavities on the same chip and demonstrate that their emission exhibits two-photon interference. The results provided a path to integrate multiple quantum emitters and cavities on-a-chip for scalable quantum photonics applications.
This research paper demonstrated two-photon interference from independent cavity coupled dots on the same chip. The researchers combined thermal tuning of quantum dots with nitrogen gas deposition and local evaporation to match the resonances of both cavities and dots. From this, they attained a two-photon interference visibility of 0.33. This was an indication that they attained sufficient tuning range and precision to match individual separated dots. This is a special requirement for scalable quantum photonics applications. The outcomes presented an important step towards scalable quantum integrated photonic devices composed of multiple sources for photonic quantum information processing.
Je-Hyung Kim1, Christopher J. K. Richardson2, Richard P. Leavitt2, and Edo Waks1,3. Two-photon interference from the far-field emission of chip-integrated cavity-coupled emitters. Nano Letters, 2016 volume 16, pages 7061−7066.Show Affiliations
- Department of Electrical and Computer Engineering and Institute for Research in Electronics and Applied Physics, University of Maryland , College Park, Maryland 20742, United States
- Laboratory for Physical Sciences, University of Maryland , College Park, Maryland 20740, United States
- Joint Quantum Institute, University of Maryland and the National Institute of Standards and Technology , College Park, Maryland 20742, United States
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