Measurement-induced enhancement of the X-parity lifetime in a Majorana tetron
Abstract
A recent experiment [arXiv:2507.08795] has reported measurements of the interwire X-parity lifetime in a Majorana tetron device via the quantum capacitance of an auxiliary readout dot. Motivated by these measurements, we theoretically study the interwire parity lifetime in a minimal model of the coupled dot-tetron system subject to electrostatic noise. We show that coupling to the measurement dot can itself strongly modify the parity dynamics by generating an energy splitting that shifts noise-induced transitions to finite frequency and thereby stabilizes the measured states against low-frequency fluctuations. For representative noise strengths motivated by disordered nanowire devices, we find X-parity switching lifetimes of order microseconds in the measurement configuration even when the corresponding bare-tetron coherence time is only tens of nanoseconds long. We analyze both the dispersive regime, where the dot can be integrated out and the dynamics reduces to an effective two-level system, and the near-resonant regime, where all four low-energy states participate. In the latter case, rapid transitions organize the spectrum into two long-lived manifolds that approximately correspond to sectors of the combined dot-tetron X-loop parity, yielding effective two-state switching despite the underlying multilevel structure. Our results show that measurement-induced stabilization can substantially enhance the observed X-parity switching lifetime, such that the lifetime measured under continuous readout can greatly exceed the intrinsic idle T2* coherence time of the isolated Majorana tetron qubit.
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BibTeX
@misc{laubscher2026measurementinduced,
title = {{Measurement-induced enhancement of the $X$-parity lifetime in a Majorana tetron}},
author = {Katharina Laubscher and Jay D. Sau and Sankar Das Sarma},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.12223},
eprint = {2610.12223},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.12223},
}
RIS
TY - UNPB
TI - Measurement-induced enhancement of the X-parity lifetime in a Majorana tetron
AU - Katharina Laubscher
AU - Jay D. Sau
AU - Sankar Das Sarma
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.12223
UR - https://arxiv.org/abs/2610.12223
AB - A recent experiment [arXiv:2507.08795] has reported measurements of the interwire X-parity lifetime in a Majorana tetron device via the quantum capacitance of an auxiliary readout dot. Motivated by these measurements, we theoretically study the interwire parity lifetime in a minimal model of the coupled dot-tetron system subject to electrostatic noise. We show that coupling to the measurement dot can itself strongly modify the parity dynamics by generating an energy splitting that shifts noise-induced transitions to finite frequency and thereby stabilizes the measured states against low-frequency fluctuations. For representative noise strengths motivated by disordered nanowire devices, we find X-parity switching lifetimes of order microseconds in the measurement configuration even when the corresponding bare-tetron coherence time is only tens of nanoseconds long. We analyze both the dispersive regime, where the dot can be integrated out and the dynamics reduces to an effective two-level system, and the near-resonant regime, where all four low-energy states participate. In the latter case, rapid transitions organize the spectrum into two long-lived manifolds that approximately correspond to sectors of the combined dot-tetron X-loop parity, yielding effective two-state switching despite the underlying multilevel structure. Our results show that measurement-induced stabilization can substantially enhance the observed X-parity switching lifetime, such that the lifetime measured under continuous readout can greatly exceed the intrinsic idle T_2^* coherence time of the isolated Majorana tetron qubit.
ER -