Researchers have proposed a new method to read quantum information from Andreev qubits without destroying it, using the qubit's own oscillating supercurrent as a non-destructive measurement signal, eliminating the need for auxiliary qubits.
The study, published in Physical Review B Letters and led by José Carlos Egues of the University of São Paulo and Yugui Yao of the Beijing Institute of Technology, shows the supercurrent's constant and oscillating components encode the qubit's state. A SQUID detects the current's magnetic field, allowing state reconstruction with minimal perturbation, achieving simulation accuracies up to 99.85%.
The theoretical proposal uses realistic parameters from existing systems, requiring no new technology. It predicts a voltage-free alternating supercurrent generated by the qubit's own evolution, potentially simplifying quantum computing architectures by removing ancillas and enabling successive measurements without resetting the qubit.