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Dephasing and leakage dynamics of noisy Majorana-based qubits: Topological versus Andreev

Mishmash, Ryan V. and Bauer, Bela and von Oppen, Felix and Alicea, Jason (2020) Dephasing and leakage dynamics of noisy Majorana-based qubits: Topological versus Andreev. Physical Review B, 101 (7). Art. No. 075404. ISSN 2469-9950.

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Topological quantum computation encodes quantum information nonlocally by nucleating non-Abelian anyons separated by distances L, typically spanning the qubit device size. This nonlocality renders topological qubits exponentially immune to dephasing from all sources of classical noise with operator support local on the scale of L. We perform detailed analytical and numerical analyses of a time-domain Ramsey-type protocol for noisy Majorana-based qubits that is designed to validate this coveted topological protection in near-term devices such as the so-called “tetron” design. By assessing dependence of dephasing times on tunable parameters, e.g., magnetic field, our proposed protocol can clearly distinguish a bona fide Majorana qubit from one constructed from semilocal Andreev bound states, which can otherwise closely mimic the true topological scenario in local probes. In addition, we analyze leakage of the qubit out of its low-energy manifold due to classical-noise-induced generation of quasiparticle excitations; leakage limits the qubit lifetime when the bulk gap collapses, and hence our protocol further reveals the onset of a topological phase transition. This experiment requires measurement of two nearby Majorana modes for both initialization and readout—achievable, for example, by tunnel coupling to a nearby quantum dot—but no further Majorana manipulations, and thus constitutes an enticing prebraiding experiment. Along the way, we address conceptual subtleties encountered when discussing dephasing and leakage in the context of Majorana qubits.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bauer, Bela0000-0001-9796-2115
Alicea, Jason0000-0001-9979-3423
Additional Information:© 2020 American Physical Society. Received 25 November 2019; accepted 9 January 2020; published 3 February 2020. The authors thank A. Antipov, W. Cole, T. Karzig, E. Rossi, and M. Zaletel for useful discussions. This work was supported by CRC 183 of Deutsche Forschungsgemeinschaft (F.v.O.); QuantERA project TOPOQUANT (F.v.O.); sabbatical support from IQIM, an NSF physics frontier center funded in part by the Moore Foundation (F.v.O.); the Army Research Office under Grant Award No. W911NF17-1-0323 (J.A.); the NSF through Grant No. DMR-1723367 (J.A.); the Caltech Institute for Quantum Information and Matter, an NSF Physics Frontiers Center with support of the Gordon and Betty Moore Foundation through Grant No. GBMF1250 (R.V.M. and J.A.); the Walter Burke Institute for Theoretical Physics at Caltech (R.V.M. and J.A.); and the Gordon and Betty Moore Foundation's EPiQS Initiative, Grant No. GBMF8682 (J.A.). Part of this work was performed at the Aspen Center for Physics, which is supported by National Science Foundation Grant No. PHY-1607611 (R.V.M.).
Group:UNSPECIFIED, Institute for Quantum Information and Matter, Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)CRC 183
Institute for Quantum Information and Matter (IQIM)UNSPECIFIED
Gordon and Betty Moore FoundationGBMF1250
Army Research Office (ARO)W911NF17-1-0323
Walter Burke Institute for Theoretical Physics, CaltechUNSPECIFIED
Gordon and Betty Moore FoundationGBMF8682
Issue or Number:7
Record Number:CaltechAUTHORS:20200203-105634945
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101070
Deposited By: Tony Diaz
Deposited On:03 Feb 2020 19:05
Last Modified:04 Jun 2020 10:14

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