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Paper 1
Robustness of QMA against witness noise
Friederike Anna Dziemba
- Year
- 2016
- Journal
- arXiv preprint
- DOI
- arXiv:1611.07332
- arXiv
- 1611.07332
Using the tool of concatenated stabilizer coding, we prove that the complexity class QMA remains unchanged even if every witness qubit is disturbed by constant noise. This result may not only be relevant for physical implementations of verifying protocols but also attacking the relationship between the complexity classes QMA, QCMA and BQP, which can be reformulated in this unified framework of a verifying protocol receiving a disturbed witness. While QCMA and BQP are described by fully dephasing and depolarizing channels on the witness qubits, respectively, our result proves QMA to be robust against 27% dephasing and 18% depolarizing noise.
Open paperPaper 2
Nonexponential quantum decay under environmental decoherence
M. Beau, J. Kiukas, I. L. Egusquiza, A. del Campo
- Year
- 2017
- Journal
- arXiv preprint
- DOI
- arXiv:1706.06943
- arXiv
- 1706.06943
An unstable quantum state generally decays following an exponential law, as environmental decoherence is expected to prevent the decay products from recombining to reconstruct the initial state. Here we show the existence of deviations from exponential decay in open quantum systems under very general conditions. Our results are illustrated with the exact dynamics under quantum Brownian motion and suggest an explanation of recent experimental observations.
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