Arrival-time problem in the quantum information era - observation of a Zeno crossover in monitored arrival-time distributions
Abstract
When does a quantum particle arrive at a detector? The temporal distributions of itinerant quantum particles have been debated since the birth of quantum mechanics. Here we study the arrival-time problem in periodically monitored spin chains and quantum circuits. The arrival dynamics exhibits two regimes, the quantum Zeno and the low-monitoring regime, separated by an optimal monitoring period set by the single-particle bandwidth. In support of the theory, on superconducting quantum hardware, we measure arrival-time distributions for single and multiple interacting particles in one- and two-dimensional circuits. The measured distributions resolve both regimes and agree closely with quantum-trajectory theory. The crossover persists in interacting many-particle systems: the optimal monitoring point is preserved while many-body interference reshapes the distributions. Zeno suppression likewise persists in two-dimensional geometry. Together, these results show that the two regimes are a generic feature of monitored propagation rather than a single-particle effect. To our knowledge, our work constitutes the first experimental measurement of arrival-time distributions in a monitored quantum transport setting, addressing one of the longest-standing problems in quantum mechanics.
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BibTeX
@misc{mafi2026arrivaltime,
title = {{Arrival-time problem in the quantum information era - observation of a Zeno crossover in monitored arrival-time distributions}},
author = {Yousef Mafi and K. G. S. H. Gunawardana and Kim Pöyhönen and Teemu Ojanen},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.09814},
eprint = {2611.09814},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.09814},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Arrival-time problem in the quantum information era - observation of a Zeno crossover in monitored arrival-time distributions
AU - Yousef Mafi
AU - K. G. S. H. Gunawardana
AU - Kim Pöyhönen
AU - Teemu Ojanen
PY - 2026
DA - 2026/11/06
PB - arXiv
DO - 10.48550/arxiv.2611.09814
UR - https://arxiv.org/abs/2611.09814
AB - When does a quantum particle arrive at a detector? The temporal distributions of itinerant quantum particles have been debated since the birth of quantum mechanics. Here we study the arrival-time problem in periodically monitored spin chains and quantum circuits. The arrival dynamics exhibits two regimes, the quantum Zeno and the low-monitoring regime, separated by an optimal monitoring period set by the single-particle bandwidth. In support of the theory, on superconducting quantum hardware, we measure arrival-time distributions for single and multiple interacting particles in one- and two-dimensional circuits. The measured distributions resolve both regimes and agree closely with quantum-trajectory theory. The crossover persists in interacting many-particle systems: the optimal monitoring point is preserved while many-body interference reshapes the distributions. Zeno suppression likewise persists in two-dimensional geometry. Together, these results show that the two regimes are a generic feature of monitored propagation rather than a single-particle effect. To our knowledge, our work constitutes the first experimental measurement of arrival-time distributions in a monitored quantum transport setting, addressing one of the longest-standing problems in quantum mechanics.
ER -