A team of researchers from various institutions, including the University of New South Wales and Simon Fraser University, have developed a new readout technique that enhances the fidelity of qubit measurements in quantum computing. The technique amplifies correlations between a pair of single-electron transistors, known as a twin SET, and reduces charge readout infidelity by over an order of magnitude compared to traditional methods. The method also allows for faster measurements and enhances signals corresponding to charge transitions that take place farther away from the sensors, which could help overcome challenges in large arrays of qubits.
Introduction to the Study
A team of researchers from the School of Electrical Engineering and Telecommunications at The University of New South Wales, Diraq, Leibniz-Institut für Kristallzüchtung, VITCON Projectconsult GmbH, and the Department of Physics at Simon Fraser University have developed a new technique to improve the readout fidelity in quantum computing.
The Importance of High-Fidelity Qubit Readout
High-fidelity qubit readout is crucial for achieving the thresholds needed to implement quantum error-correction protocols and achieve fault-tolerant quantum computing. Large-scale silicon qubit devices will have densely packed arrays of quantum dots with multiple charge sensors that are on average farther away from the quantum dots, resulting in a reduction in readout fidelities.
The New Readout Technique
The team presents a readout technique that enhances the readout fidelity in a linear SiMOS four-dot array by amplifying correlations between a pair of single-electron transistors, known as a twin SET. By recording and subsequently correlating the twin SET traces as they modulate the dot detuning across a charge transition, they demonstrate a reduction in the charge readout infidelity by over one order of magnitude compared to traditional readout methods.
Studying Spin-to-Charge Conversion Errors
The researchers also studied the spin-to-charge conversion errors introduced by the modulation technique. They concluded that faster modulation frequencies avoid relaxation-induced errors without introducing significant spin-flip errors, favoring the use of the technique at short integration times.
Implications of the Technique
This method not only allows for faster and higher-fidelity qubit measurements, but it also enhances the signal corresponding to charge transitions that take place farther away from the sensors. This enables a way to circumvent the reduction in readout fidelities in large arrays of qubits, which is a significant advancement in the field of quantum computing.
The Modulation Technique and SET Correlations
The device measured in this work consists of a linear four-dot SiMOS device on isotopically enriched silicon where quantum dots are electrostatically defined by aluminum gates. The device includes two rfSETs, one on each end of the dot array. This twin SET configuration enables the detection of charge correlations to improve the readout fidelity.
Summary
The study presents a significant advancement in the field of quantum computing by proposing a new technique to improve the readout fidelity in quantum computing. The technique allows for faster and higher-fidelity qubit measurements and enhances the signal corresponding to charge transitions that take place farther away from the sensors. This could pave the way for the development of more efficient and reliable quantum computing systems.
The article titled “Improved Single-Shot Qubit Readout Using Twin rf-SET Charge Correlations” was published on January 3, 2024, in the journal PRX Quantum. The authors of the study include Santiago Serrano, MengKe Feng, Wee Han Lim, Amanda E. Seedhouse, Tuomo Tanttu, Will Gilbert, Christopher C. Escott, N. V. Abrosimov, H.‐J. Pohl, M. L. W. Thewalt, Fay E. Hudson, André Saraiva, A. S. Dzurak, and Arne Laucht. The article can be accessed through its DOI reference https://doi.org/10.1103/prxquantum.5.010301.
