Effects of strongly coupled coherent two-level-systems on the coherence times of superconducting qubits

Superconducting qubits are a prominent platform for quantum computing, critical to both industrial and academic endeavors. Although these are easily scalable due to their compatibility with the recent microelectronics technology, they are prone to noise. An active area of research is the enhancement of superconducting qubit coherence times. One of the significant factors limiting the coherence times of superconducting qubits is parasitic two-level system (TLS) defects. The exact mechanism of interaction between a qubit and various types of TLS defects remains unexplored mainly due to the lack of experimental techniques to probe the form of qubit-defect couplings. Here, we present a model where the strong coupling of a TLS at specific coupling angles leads to longer coherence times. Such models can provide a pathway to transfer information through TLSs near the qubit environment as they can potentially perform the role of temporary information storage entities. We also show that this phenomenon occurs due to a correlation between the qubit and TLS. 

Reference: Shi, Jianxin. Advances in Condensed Matter Physics 2020 (2020): 1-8.