Understanding the effects of leakage in superconducting quantum-error-detection circuits
Abstract
The majority of quantum-error-detection and correction protocols assume that the population in a qubit does not leak outside of its computational subspace. For many existing approaches, however, the physical qubits do possess more than two energy levels and consequently are prone to such leakage events. Analyzing the effects of leakage is therefore essential to devise optimal protocols for quantum gates, measurement, and error correction. In this article, we present a detailed study of leakage in a two-qubit superconducting stabilizer measurement circuit. We simulate the repeated ancilla-assisted measurement of a single σz operator for a data qubit, record the outcome at the end of each measurement cycle, and explore the signature of leakage events in the obtained readout statistics. An analytic model is also developed that closely approximates the results of our numerical simulations. We find that leakage leads to destructive features in the quantum-error-detection scheme, making additional hardware and software protocols necessary.
- Publication:
-
Physical Review A
- Pub Date:
- December 2013
- DOI:
- 10.1103/PhysRevA.88.062329
- arXiv:
- arXiv:1306.0925
- Bibcode:
- 2013PhRvA..88f2329G
- Keywords:
-
- 03.67.Lx;
- 03.67.Pp;
- 85.25.-j;
- Quantum computation;
- Quantum error correction and other methods for protection against decoherence;
- Superconducting devices;
- Quantum Physics
- E-Print:
- 8 pages, 4 figures. Accepted in Phys. Rev. A