Accurate Qubit Control with Single Flux Quantum Pulses
Abstract
The primary objective of the proposed three-year research effort is to explore high-fidelity coherent control of a superconducting qubit using Single Flux Quantum (SFQ) logic circuits that generate the appropriate classical control pulses. The proposed effort will also explore the integration of superconducting qubits with classical SFQ logic circuits in the cold stages of a dilution refrigerator. The overall proposed approach is to experimentally explore coherent quantum control of superconducting qubits by direct excitation via Single Flux Quantum (SFQ) voltage pulses, based on previous theoretical studies. These theoretical studies, with supporting Monte Carlo simulations, indicate that high-fidelity quantum logic gates, that are robust against leakage errors and timing jitter, can be performed with SFQ pulses. Fidelities in excess of 99.9% with gate times of about 20 nanoseconds are predicted. For the proposed experiments, integrating the SFQ circuit on the same chip as the qubit is likely to lead to a degradation of qubit performance due to quasiparticles produced by the high energy SFQ circuits. Quasiparticle distributions and poisoning will be measured to pursue mitigation approaches. Several concepts have been proposed and these will be tested. SFQ-pulse sequences will be designed to effectively shape control pulses for high fidelity single qubit rotations and two-qubit gates. An alternate approach to quantum control which utilizes Josephson-based microwave pulses will also be pursued. In this case, the control circuit can be fabricated on a separate chip. This approach is not optimal for integration and compactness but could be significantly more robust against quasiparticle poisoning.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510248
Entities
People
- Robert Mcdermott
Organizations
- Army Contracting Command
- National Security Agency
- University of Wisconsin–Madison