超导量子比特作为粒子探测器的定量表征
Quantitative characterization of superconducting qubits as particle detectors
- INFN – Sezione di Roma（意大利国家核物理研究所罗马分部）
- Gran Sasso Science Institute（格兰萨索科学研究所）
- INFN – Laboratori Nazionali del Gran Sasso（意大利国家核物理研究所格兰萨索国家实验室）
- Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università degli Studi di Padova（帕多瓦大学伽利略伽利雷物理与天文系）
- ENEA Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (INMRI)（欧洲原子能机构电离辐射计量国立研究所）
- Sapienza Università di Roma（罗马第一大学）
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)（费米国家加速器实验室超导量子材料与系统部）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过结合半导体低温传感器，首次直接测量了超导量子比特的探测效率（约30-40%），并确定有效能量阈值上限，证明辐射响应不能仅由热效应解释。
AI中文摘要：
电离辐射是超导量子处理器中相关错误的主要来源，然而，量子比特对粒子相互作用响应的机制仍仅被部分理解。在本工作中，我们将超导量子比特作为粒子探测器运行，同时用独立的半导体低温传感器监测沉积能量。这种互补测量提供了芯片中粒子相互作用率的绝对测定，从而首次直接测量了暴露于环境辐射的超导量子比特的探测效率。我们测得单个量子比特的探测效率约为30-40%，当结合两个量子比特的响应时，该效率增加到约50%。在保守假设效率损失完全由有限探测阈值决定的情况下，我们推导出探测器有效能量阈值的上限为$70\pm20~\mathrm{(stat)}\pm30~\mathrm{(syst)}~\mathrm{keV}$。使用产生不同沉积能量谱的放射源的测量进一步表明，探测效率在较低能量相互作用时降低。我们进一步通过电阻加热器注入受控热脉冲来研究量子比特响应的起源。尽管这些脉冲沉积的能量与粒子相互作用释放的能量相当，但它们并未重现辐射诱导的特征，表明量子比特对辐射的响应不能仅用衬底温度的瞬态增加来解释。我们的结果建立了一个实验框架，用于定量地将粒子能量沉积与超导量子电路中的辐射诱导响应联系起来。
英文摘要：
Ionizing radiation is a major source of correlated errors in superconducting quantum processors, yet the mechanisms responsible for the qubit response to particle interactions remain only partially understood. In this work, we operate superconducting qubits as particle detectors while simultaneously monitoring the deposited energy with an independent semiconductor cryogenic sensor. This complementary measurement provides an absolute determination of the particle interaction rate in the chip, enabling the first direct measurement of the detection efficiency of superconducting qubits exposed to environmental radiation. We measure individual qubit detection efficiencies of about 30-40$\%$, increasing to approximately 50$\%$ when combining the response of two qubits. Under the conservative assumption that the efficiency loss is entirely determined by a finite detection threshold, we derive an upper limit on the effective energy threshold of the detector of $70\pm20~\mathrm{(stat)}\pm30~\mathrm{(syst)}~\mathrm{keV}$. Measurements with radioactive sources producing different deposited-energy spectra further show that the detection efficiency decreases for lower-energy interactions. We further investigate the origin of the qubit response by injecting controlled thermal pulses with a resistive heater. Although these pulses deposit energies comparable to those released by particle interactions, they do not reproduce the radiation-induced signatures, demonstrating that the qubit response to radiation cannot be explained by a transient increase in substrate temperature alone. Our results establish an experimental framework for quantitatively connecting particle energy deposition to radiation-induced responses in superconducting quantum circuits.
