WARF TECHNOLOGIES

Current approaches to quantum error correction rely on large-scale networks of interacting qubits to uniquely identify errors in the array. Robust error correction has two requirements: the error rate must be below the fault tolerant threshold, and errors must be uncorrelated. Fluctuating offset charge in superconducting qubit arrays is highly correlated on length scales of order hundreds of microns. Discrete changes in offset charge are accompanied by a strong transient suppression of qubit T1 across the millimeter-scale chip. The correlated dephasing and relaxation errors are explained in terms of absorption in the qubit substrate of high-energy particles, namely, cosmic ray muons and gamma-rays due to low-level radioactivity. Accordingly, there is a need for devices and methods for downconversion of pair-breaking phonons in superconducting quantum circuits.

Researchers at UW-Madison and Syracuse University have developed a simple, robust method for forming thick normal metal islands on the back side of the qubit substrate for the purposes of down converting pair-breaking phonons. The thick layer is formed by a standard blanket electroplating process on a pre-deposited seed layer. In order to form isolated islands, the blanket layer can be broken up by a number of alternative mechanical means.

For More Information About the Inventors

• Robert McDermott

Tech Fields

• Semiconductors & Integrated Circuits : Quantum dot technologies