2019/01/14 by Matthew Curry, Curry, M. J., M. S. Rudolph +27 · 1 citation
Computer Science · Physics and Astronomy · #FOS: Physical sciences #Magnetic properties of thin films #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum Computing Algorithms and Architecture #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.1901.04570
openalex publication_date 2019/01/14 · openalex created_date 2019/01/25 · openalex updated_date 2026/07/28
High-fidelity single-shot readout of spin qubits requires distinguishing states much faster than the T1 time of the spin state. One approach to improving readout fidelity and bandwidth (BW) is cryogenic amplification, where the signal from the qubit is amplified before noise sources are introduced and room-temperature amplifiers can operate at lower gain and higher BW. We compare the performance of two cryogenic amplification circuits: a current-biased heterojunction bipolar transistor circuit (CB-HBT), and an AC-coupled HBT circuit (AC-HBT). Both circuits are mounted on the mixing-chamber stage of a dilution refrigerator and are connected to silicon metal oxide semiconductor (Si-MOS) quantum dot devices on a printed circuit board (PCB). The power dissipated by the CB-HBT ranges from 0.1 to 1 μW whereas the power of the AC-HBT ranges from 1 to 20 μW. Referred to the input, the noise spectral density is low for both circuits, in the 15 to 30 fA/√\textrmHz range. The charge sensitivity for the CB-HBT and AC-HBT is 330 μe/√\textrmHz and 400 μe/√\textrmHz, respectively. For the single-shot readout performed, less than 10 μs is required for both circuits to achieve bit error rates below 10-3, which is a putative threshold for quantum error correction.