论文标题
在MK温度下进行射频测量的量子副型变量
Quantum paraelectric varactors for radio-frequency measurements at mK temperatures
论文作者
论文摘要
射频反射仪可以快速，敏感的电气读数，并托管在量子点设备与共振电路的量子点设备中托管。但是，优化读数需要对谐振器进行频率调整和阻抗匹配。这很难使用检测回路中的常规半导体或基于铁电的变量，因为它们的性能在与固态量子设备相关的MK温度范围内显着降解。在这里，我们探索了一种不同类型的材料，钛酸锶，一种量子副型，在低温下具有异常大的场合 - 可调介电常数。我们使用钛酸钛酸变量，我们在6 MK处表现出完美的阻抗匹配和谐振频率调整，并以其电容可调性，耗散性损耗和磁场灵敏度来表征该温度下的变量。我们表明，这使我们能够优化碳纳米管量子点设备的射频读数信噪比，以达到4.8 $ $ $ e/hz $^{1/2} $的电荷灵敏度，并且电容敏感性为0.04 af/hz $^{1/2} $。
Radio-frequency reflectometry allows for fast and sensitive electrical readout of charge and spin qubits hosted in quantum dot devices coupled to resonant circuits. Optimizing readout, however, requires frequency tuning of the resonators and impedance matching. This is difficult to achieve using conventional semiconductor or ferroelectric-based varactors in the detection circuit as their performance degrades significantly in the mK temperature range relevant for solid-state quantum devices. Here we explore a different type of material, strontium titanate, a quantum paraelectric with exceptionally large field-tunable permittivity at low temperatures. Using strontium titanate varactors we demonstrate perfect impedance matching and resonator frequency tuning at 6 mK and characterize the varactors at this temperature in terms of their capacitance tunability, dissipative losses and magnetic field sensitivity. We show that this allows us to optimize the radio-frequency readout signal-to-noise ratio of carbon nanotube quantum dot devices to achieve a charge sensitivity of 4.8 $μ$e/Hz$^{1/2}$ and capacitance sensitivity of 0.04 aF/Hz$^{1/2}$.
