S. Valles-Sanclemente

Post-fabrication frequency trimming of coplanar-waveguide resonators in circuit QED quantum processors

  1. S. Vallés-Sanclemente,
  2. S. L. M. van der Meer,
  3. M. Finkel,
  4. N. Muthusubramanian,
  5. M. Beekman,
  6. H. Ali,
  7. J. F. Marques,
  8. C. Zachariadis,
  9. H. M. Veen,
  10. T. Stavenga,
  11. N. Haider,
  12. and L. DiCarlo
We present the use of grounding airbridge arrays to trim the frequency of microwave coplanar-waveguide (CPW) resonators post fabrication. This method is compatible with the fabrication
steps of conventional CPW airbridges and crossovers and increases device yield by allowing compensation of design and fabrication uncertainty with 100 MHz range and 10 MHz resolution. We showcase two applications in circuit QED. The first is elimination of frequency crowding between resonators intended to readout different transmons by frequency-division multiplexing. The second is frequency matching of readout and Purcell-filter resonator pairs. Combining this matching with transmon frequency trimming by laser annealing reliably achieves fast and high-fidelity readout across 17-transmon quantum processors.
arxiv pdf

All-microwave leakage reduction units for quantum error correction with superconducting transmon qubits

  1. J. F. Marques,
  2. H. Ali,
  3. B. M. Varbanov,
  4. M. Finkel,
  5. H. M. Veen,
  6. S. L. M. van der Meer,
  7. S. Valles-Sanclemente,
  8. N. Muthusubramanian,
  9. M. Beekman,
  10. N. Haider,
  11. B. M. Terhal,
  12. and L. DiCarlo
Minimizing leakage from computational states is a challenge when using many-level systems like superconducting quantum circuits as qubits. We realize and extend the quantum-hardware-efficient,
all-microwave leakage reduction unit (LRU) for transmons in a circuit QED architecture proposed by Battistel et al. This LRU effectively reduces leakage in the second- and third-excited transmon states with up to 99% efficacy in 220 ns, with minimum impact on the qubit subspace. As a first application in the context of quantum error correction, we demonstrate the ability of multiple simultaneous LRUs to reduce the error detection rate and to suppress leakage buildup within 1% in data and ancilla qubits over 50 cycles of a weight-2 parity measurement.
arxiv pdf