(YIP) LIMITING PHONON-INDUCED DECOHERENCE IN SUPERCONDUCTING QUBITS
Abstract
Superconducting qubits are a highly promising platform for quantum technologies because of their design flexibility, ease of control, and lithographic scalability. However, the next phases of implementing quantum error correction and large-scale quantum computing are limited primarily by qubit coherence time. One source of decoherence arises from high-energy non-equilibrium phonons, or excess vibrational energy. For example, though superconducting qubits operate at temperatures below 1 K, at which phonons have extremely low energies, impinging ionizing radiation from cosmic rays and trace radioactive impurities impart energy to phonons along their pathway through the device. These excited phonons have much higher energy and are out of equilibrium with the thermal bath. They travel throughout the substrate and break Cooper pairs upon transmission to the superconducting layer. Phonon-induced decoherence is particularly damaging because resulting qubit errors are correlated in space and time, undermining algorithms for quantum error correction. As quantum processors scale up to millions of qubits, phononinduced decoherence will potentially dominate the qubit performance. The goal of our work is to reveal the underlying processes that govern phonon-induced decoherence in superconducting qubits, from the energies of phonons generated by ionizing radiation to the transport of phonons across the device and finally to their interactions in the superconductor. We will use the fundamental knowledge gained to design novel mitigation strategies and evaluate their effectiveness by fabricating and characterizing the performance of superconducting qubit devices. We expect to offer new robust mitigation strategies that protect superconducting qubits from nonequilibrium phonons, a step towards sustaining the coherence times necessary for the next era in quantum technology and helping build the competitive quantum capacities for the U.S. Air Force.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 07, 2023
- Source ID
- FA95502210177
Entities
People
- Zhiting Tian
Organizations
- Air Force Office of Scientific Research
- Cornell University
- United States Air Force