Characterization of Spin Qubits

We use lasers and microwave fields to study the optical and spin properties of optically-active spins in the solid-state. These measurements evaluate the performance of the studied systems for quantum information processing, networking, and sensing.


The characterized optical properties include the wavelength, lifetime, indistinguishability, and inhomogeneous linewidth of emitted single photons.


The characterized spin properties include the pure dephasing, decoherence, and spin relaxation rates, as well as the noise sources that lead to these decay mechanisms.    

In the figure: realization of all-optical pulse sequences of coherent control to characterize the noise sources that lead to the loss of coherence of quantum dots

Promising research directions:

  • Development of hybrid microwave and optical control for the optimal characterization of spin qubits.
  • Experimental realization of compressed sensing for the resource-efficient characterization of noise sources with sparse features.
  • Characterization of novel systems:
    • 1. Quantum dots and color centers that emit at telecom wavelengths, which are crucial for quantum communication and networking.
    • 2. Unstrained quantum dots with long spin coherence times for quantum information processing.
    • 3. “Molecules” of vertically stacked quantum dots, which feature long coherence times and are promising for quantum networking.

Related publications:

  • K. Huang, D. Farfurnik, A. Seif, M. Hafezi, and Y-K. Liu. Random Pulse Sequences for Qubit Noise Spectroscopy. arXiv:2303.00909.
  • D. Farfurnik, H. Singh, Z. Luo, A. S. Bracker, S. G. Carter, R. M. Pettit, and E. Waks.  All-Optical Noise Spectroscopy of a Solid-State Spin.  Nano Lett. 23, 1781-1786 (2023). 
  • D. Farfurnik and N. Bar-Gill. Characterizing spin-bath parameters using conventional and time-asymmetric Hahn-echo sequences. Phys. Rev. B 101, 104306 (2020).