TY - JOUR
T1 - Leakage detection for a transmon-based surface code
AU - Varbanov, Boris Mihailov
AU - Battistel, Francesco
AU - Tarasinski, Brian Michael
AU - Ostroukh, Viacheslav Petrovych
AU - O’Brien, Thomas Eugene
AU - DiCarlo, Leonardo
AU - Terhal, Barbara Maria
PY - 2020
Y1 - 2020
N2 - Leakage outside of the qubit computational subspace, present in many leading experimental platforms, constitutes a threatening error for quantum error correction (QEC) for qubits. We develop a leakage-detection scheme via Hidden Markov models (HMMs) for transmon-based implementations of the surface code. By performing realistic density-matrix simulations of the distance-3 surface code (Surface-17), we observe that leakage is sharply projected and leads to an increase in the surface-code defect probability of neighboring stabilizers. Together with the analog readout of the ancilla qubits, this increase enables the accurate detection of the time and location of leakage. We restore the logical error rate below the memory break-even point by post-selecting out leakage, discarding less than half of the data for the given noise parameters. Leakage detection via HMMs opens the prospect for near-term QEC demonstrations, targeted leakage reduction and leakage-aware decoding and is applicable to other experimental platforms.
AB - Leakage outside of the qubit computational subspace, present in many leading experimental platforms, constitutes a threatening error for quantum error correction (QEC) for qubits. We develop a leakage-detection scheme via Hidden Markov models (HMMs) for transmon-based implementations of the surface code. By performing realistic density-matrix simulations of the distance-3 surface code (Surface-17), we observe that leakage is sharply projected and leads to an increase in the surface-code defect probability of neighboring stabilizers. Together with the analog readout of the ancilla qubits, this increase enables the accurate detection of the time and location of leakage. We restore the logical error rate below the memory break-even point by post-selecting out leakage, discarding less than half of the data for the given noise parameters. Leakage detection via HMMs opens the prospect for near-term QEC demonstrations, targeted leakage reduction and leakage-aware decoding and is applicable to other experimental platforms.
UR - http://www.scopus.com/inward/record.url?scp=85097577018&partnerID=8YFLogxK
U2 - 10.1038/s41534-020-00330-w
DO - 10.1038/s41534-020-00330-w
M3 - Article
AN - SCOPUS:85097577018
SN - 2056-6387
VL - 6
JO - NPJ Quantum Information
JF - NPJ Quantum Information
IS - 1
M1 - 102
ER -