A Spin-Photon Interface Using Charge-Tunable Quantum Dots Strongly Coupled to a Cavity.

Nano Lett

Department of Electrical and Computer Engineering, Institute for Research in Electronics and Applied Physics, and Joint Quantum Institute , University of Maryland , College Park, Maryland 20742 , United States.

Published: October 2019

AI Article Synopsis

  • Charged quantum dots are effective solid-state qubits that can enhance quantum networks by utilizing the spin of electrons or holes to control photons in photonic cavities.
  • Previous methods faced issues with stability due to random charging from impurities, affecting performance.
  • This study presents a technique using deterministically charged quantum dots, achieving strong spin-photon coupling and significant enhancements in cavity reflectivity, enabling better entanglement and photon interactions for advanced quantum computing applications.*

Article Abstract

Charged quantum dots containing an electron or hole spin are bright solid-state qubits suitable for quantum networks and distributed quantum computing. Incorporating such quantum dot spin into a photonic crystal cavity creates a strong spin-photon interface in which the spin can control a photon by modulating the cavity reflection coefficient. However, previous demonstrations of such spin-photon interfaces have relied on quantum dots that are charged randomly by nearby impurities, leading to instability in the charge state, which causes poor contrast in the cavity reflectivity. Here we demonstrate a strong spin-photon interface using a quantum dot that is charged deterministically with a diode structure. By incorporating this actively charged quantum dot in a photonic crystal cavity, we achieve strong coupling between the cavity mode and the negatively charged state of the dot. Furthermore, by initializing the spin through optical pumping, we show strong spin-dependent modulation of the cavity reflectivity, corresponding to a cooperativity of 12. This spin-dependent reflectivity is important for mediating entanglement between spins using photons, as well as generating strong photon-photon interactions for applications in quantum networking and distributed quantum computing.

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Source
http://dx.doi.org/10.1021/acs.nanolett.9b02443DOI Listing

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