Fast Gate-Based Readout of Silicon Quantum Dots Using Josephson Parametric Amplification

Abstract

pling α and the inverse of the total capacitance of the resonator [22]. Recently, single-shot readout of the singlettriplet states in a double QD has been demonstrated with gate-based sensors, using a variety of resonator parameters to achieve a range of readout fidelities (for a given integration time): 73% (2.6 ms) [23], 82.9% (300 µs) [24], 98% (6 µs) [25] to 99% (1 ms; using ancillary 'sensor' QD and reservoir) [26].Amplifiers based on Josephson junctions have greatly improved signal-to-noise ratios (SNRs) in the field of superconducting circuits [27-32] -they typically operate at frequencies of several GHz and near the quantum limit of noise introduced by the amplifier (or indeed below, for a single quadrature using squeezing) [33][34][35][36][37][38]. Adopting such approaches in the measurement of QDs at RF/microwave frequencies is expected to lead to corresponding improvements in SNR. While this can in principle be achieved at operating frequencies of 4-8 GHz that are typical for Josephson-junction based amplifiers, as demonstrated using an InAs double QD, Josephson parametric amplifier (JPA) and coplanar waveguide resonator [39], lower frequency operation ( 1 GHz) becomes necessary [40] for studying lower QD tunneling rates, at which exchange interaction is more easily controlled, and for enabling off-chip resonator fabrication. Suitable amplifiers are available in such a frequency range, for example: a JPA operating at 600 MHz with a noise temperature of T JPA = 105 mK [41] or a SQUID amplifier chain with T SQUID = 52 mK at 538 MHz [42]. Building on such developments, readout of a GaAs based arXiv:1907.09429v2 [cond-mat.mes-hall]

Charge Detection in an Array of CMOS Quantum Dots

“…The noise on our measurement is estimated to be around 0.1 nV/ √ Hz, which is equivalent to a noise temperature of 4.5 K and corresponds to the noise of the cryogenic amplifier used here. Noise could be reduced by use of a superconducting amplifier such as a Josephson parametric amplifier [41], which would decrease the noise temperature by more than 1 order of magnitude. In the case of the embedded-SET-based measurement, the amplitude of the signal can be increased by use of modern transimpedance amplifiers, which are now operational at dilution temperatures [42].…”

Sensitive radiofrequency readout of quantum dots using an ultra-low-noise SQUID amplifier

“…The fast measurements of a double quantum dot presented above demonstrate a minimum per-pixel integration time τ min ≈ 25 ns. This integration time is of the same order as the integration times in doublequantum dot measurements using Josephson parametric amplifiers [29,36] or high quality-factor microwave resonators [27], but was enabled by a commercially available amplifier without the need for a dedicated fabrication environment. In another application of our circuit, the improved sensitivity provided by the SQUID has enabled time-resolved measurements of a vibrating carbon nanotube transistor [52].…”

“…Such amplifiers allow rapid measurements of charge parity in a double quantum dot [29]. However, the JPAs previously used for quantum dot readout have a linear amplification range limited to an input power of −130 dBm [29,36], they require a circulator inside the cryostat and a dedicated pump oscillator, and they are not commercially available. Most JPAs are optimized for a microwave frequency range well above 1 GHz, although operation as low as 650 MHz has been demonstrated [36,37].…”

“…However, the JPAs previously used for quantum dot readout have a linear amplification range limited to an input power of −130 dBm [29,36], they require a circulator inside the cryostat and a dedicated pump oscillator, and they are not commercially available. Most JPAs are optimized for a microwave frequency range well above 1 GHz, although operation as low as 650 MHz has been demonstrated [36,37]. However, a lower frequency is desirable because the charge dipole in a singlet-triplet qubit only responds adiabatically to changes in the electric field if the interdot tunnel rate is much larger than the read-out frequency.…”

Quantum interference capacitor based on double-passage Landau-Zener-Stückelberg-Majorana interferometry

“…The new wave of quantum technologies aims at using basic principles of quantum mechanics, such as superposition or entanglement, to obtain functionality beyond what conventional devices can provide 1-3 . In the field of nanoelectronics, superposition and entanglement can be harnessed to build coherent quantum circuits that can be used, for example, for quantum information processing 3 , precision sensing 4 and quantum-limited amplification 5,6 . To produce a coherent superposition between quantum states in nanoelectronic circuits, Landau-Zener-Stückelberg-Majorana (LZSM) interferometry 7,8 is a prime example.…”